$J,n
NATIONAL LIBRARY OF MEDICINE
       Bethesda, Maryland
 
 
 
 
 
 
V 
 
 
A
TEXT-BOOK

ON
ANATOMY, PHYSIOLOGY, and HYGIENE.
FOR THE USE OF
SCHOOLS  AND  FAMILIES.
         Bv JOHN C. DRAPER, M.D.,

PROFESSOR OF NATURAL HISTORY AND PHYSIOLOGY IN TUB NEW YORK FREE ACADEMY, AND PROFESSOR OF
         ANALYTICAL CHEMISTRY IN THE UNIVERSITY OF NEW YORK.
SSfitj) ©ne ^uirtiretJ anfc Sebentg Sllustratfons.
         NEW YORK:
HARPER  & BROTHERS, PUBLISHERS,
         FRANKLIN SQUARE.
             1 8 6 (i. 
/
Entered,  according to Act of Congress, in the year one thousand  eight hundred and
                                   sixty-six by

                           Harper & Brothers,

 In  the Clerk's Office of the District Court of the  Southern District of New York. 
PREFACE.
   Having been engaged for many years in lecturing upon the
various branches of Natural History, and having experienced
the difficulty that exists in attempting to teach Anatomy and
Physiology without a text-book adapted to the wants of col-
legiate  classes, I have ventured to publish my course of lec-
tures on these  subjects in the form herein presented, that the
students of the Free Academy may have every opportunity
of perfecting themselves in these branches  as  thoroughly as
the limited time devoted to them will permit.
   Although the chief object has been to prepare a text-book
for academic students, the work is also  designed for  the use
of schools and families; and  students of medicine will find
that it  contains a few hints  of value to them, especially in
Lecture XXVII., which has been added for their benefit.
   The division of Hygiene will be found to present many facts
of interest to the general reader; and, in view of the measured
but apparently inevitable approach  of cholera  to our shores,
we have in the last lecture given a short summary of the means
by which we may hope to avoid its attack.
   Anatomy and Physiology have been subjects of study for
many centuries, and there is but little that an author  can say
regarding them that is novel  or original.  I would therefore
call attention to the results of the experiments on «urea, and to
the conclusions drawn from them, and acknowledge my indebt-
edness to  the works of Carpenter, Cruveilhier, Marshall, Dun-
glison, Bowman, Draper, and many other men of science, whose
labors and writings are quoted, and whose opinions have been
adopted. 
IV
PREFACE.
  Finally, to the Board ot Education of the City of New York
I would  express my sincere thanks for the liberal manner in
which they have enlarged the ordinary collegiate course by in-
grafting on it the study of modern sciences, and enabling the
young men who graduate from the Free Academy to obtain
a knowledge of the construction and  workings of the human
system, which is by all considered to be a necessary part  of a
liberal education.
Free Academy, New York, Nov. 30, 1865. 
CONTENTS.
           FIKST DIVISION.
ANATOMY AND  STATICAL PHYSIOLOGY.
                          LECTURE I.
                         INTRODUCTION.

 Theories regarding the Nature of Life.—The Food introduced into the
  System is combustible.—The Substances voided from the Body are all
  burnt or  oxidized.—The Methods to be employed in the Examination
  of the Structure and Function of Organisms endowed with Life.— Cells
  enter into the Composition of all Tissues and Creatures .  .  .  Page 1

                          LECTURE  II.
                              CELLS.

Parts composing a Cell.— Vegetable and Animal Cells.—All living Things
  originate in and are composed of Cells.—Reproduction  of Cells.—For-
  mation of Tissues from Cells. — Secreting and protecting Cells.— Cells
  enter into the Composition of Liquids.—Nutrition of Cells.—Definitions
  of Anatomy, Physiology, and Hygiene...........3

                          LECTURE III.
                  ANATOMY OF THE HUMAN BODY.

The Tissues and Fluids composing the Body.—Divisions  of the Body.—
  Cavities of the DTead, their Contents.— Cavities of the Trunk and their
  Contents.—Subdivisions of the Extremities.—The Skeleton, its Uses.—
  Composition of Bone, and variations in the Proportions of its Ingredi-
  mts,— Diseases of Bone.— Importance of Bones in certain  Manufac-
  tures.—Microscopic Appearance of Bone.—Membranes  of Bone.—Di-
  vision and Classification of Bones............1

                          LECTURE IV.
                  BONES COMPOSING THE SKELETON.

Number of Bones in the Body.—Bones of the Trunk.—Pelvic Bones .  15

                          LECTURE  V.
                    the skeleton— Continued.

Bones of the  ZTpper Extremity.—Bones of the Lower Extremity .— Varie-
  ties of Joints.—Tissues which enter into the Composition of Joints-
  Joints  and Bones form Levers.—Diseases and  Wounds of Joints .  21 
vi
CONTENTS.
                          LECTURE  VI.
                      THE MUSCULAR SYSTEM.
The Muscular Tissue.—Microscopic Characters of voluntary and involun-
  tary Muscle Cells.— Tendons and their Position.—Divisions of Muscles.
  —Muscles of the Head and Neck.— Of the  Upper Extremities.— Of the
  Trunk.— Of the Lov^er Extremities...........Page 25

                          LECTURE VII.
                       ORGANS  OF  NUTRITION.

Divisions  of the Nutritive Process. — Divisions of the Digestive Appa-
  ratus.—Distinctive  Characters of 3Iucous  and Serous  Membranes.—
  The Composition and Classification of the Teeth.—Description of the
  Buccal Cavity.—The Pharynx.—The (Esophagus.—The Stomach.—
  The four Serous Membranes.—The Mucous Coat of the Stomach.—The
  Follicles of the Stomach.—The Ends of the Stomach.....34

                         LECTURE VIII.
                 organs of nutrition—Continued.

Divisions of the small Intestine.— Coats of the Intestine.—Movements of
  the Intestine.— Valvuke  Conniventes.— Villi, their Composition.—Divi-
  sions of the large Intestine.—Appendix Vermiformis.....41

                          LECTURE  IX.
                 organs of nutrition—Continued.

Buccal Glands.—Description of the Scdivas.—Properties of mixed Saliva.
  —Nature of Ferments.—Abdominal Glands.—Duty of the Liver.—Na-
  ture and Properties of Bile.—The Pancreas.—Nature and Properties of
  its Secretion.— Origin and Properties of Gastric Juice.— Uses of Pep-
  sin.— Origin and Properties of Intestinal Juices......  .   45

                          LECTURE X.
                               FOOD.

Annual Amount of Food consumed.—The Ingesta.—The Introduction
  and Use of Water in the System.—Latent Heat  of Vapor of Water.—
   Variation in the Food of different Nations........49

                          LECTURE  XL
                         divisions  of food.

Milk, its Composition and Variations.—The nitrogenized Group. — The
  non-nitrogenized Group.—Hydro-carbons.— Carbo-hydrates.—Fermenta-
  tion of Starch and Sugar.—Influence of Temperature on Fermentation.
  — Composition of Flour. — Bread-making. — Wine-making. — Use of
  Phosphate of Lime.— Of Chloride  of Sodium ........   51

                          LECTURE XII.
                             DIGESTION.

Mastication.—Action  of Saliva.—Action of Gastric Juice.—Formation
  and Properties of Chyme and Chyle.—Action  of Pancreatic Juice on 
CONTENTS.
vii
  Hydro-carbons  and Carbo-hydrates.— Old and new Theories of Diges-
  tion.—Digestibility of various Articles of Food.—Effect of Quantity on
  the Rate of Digestion.—Indigestion as a Disease and a Symptom.—Ef-
  fect of Nature of Diet on Length of Intestine.—Digestive Apparatus in
  certain Animals................Page 56

                         LECTURE XIII.
               CAPILLARY ATTRACTION  AND  ENDOSMOSIS.
 Composition of Fceces.— Origin  and Diurnal Amount of Fmces.—Intes-
  tinal  Gases.— Capillary Attraction.—Examples  and  Explanation of
  Capillary Attraction.—Dialysis.—The Endosmometer.—Endosmosis.—
  Exosmosis.—Action of Gum in the Endosmometer......62

                         LECTURE XIV.
                            ABSORPTION.
Mechanism  of Absorption in Plants.—Functions of the various Parts.—
  The  ascending  Sap.—The Force it exerts.—Descending Sap.—Descrip-
  tion  of a Villus.—Lacteals.—Receptaculum Chyli.—Thoracic Duct.—
  Stomach Absorption.— Villus or Intestinal Absorption.—Action of Mes-
  enteric Glands.—Effect of Disease of Mesenteric  Glands .   .  .   .  66

                          LECTURE  XV.
                               BLOOD.
Properties of Sap.— Of Blood.— Variations  in the Appearance of Blood.
  — Composition of Blood.—Influence of Sex and Climate on its Composi-
  tion.—Function of Water.— Of Albumen.— Of Extractive.— Of Fats.—
  Of Salts.— Of Fibrin.— T/ie Clot.—Action of Mesenteric and Lymphat-
  ic Glands.—Red Blood Discs.— WJiite Discs.—Hcematin.— Globulin.—
  Plasma.—Serum........'..........70

                         LECTURE XVI.
                        THE BLOOD-VESSELS.
The Divisions of Blood-vessels.—Their Composition and Character.— Or-
  der of Development of the Blood System.—The Heart described.—The
  Pericardium and Endocardium.— Muscular Tissue of the Heart.—Its
  Cavities, their relative  Position.—Rate of Pulsation.—Valves.—Their
  Function.— Valvular Sounds.—Diseases of the Valves.....76

                         LECTURE XVII.
                   the blood-vessels—Continued.
Pulmonary and Systemic Blood-vessels.— Course of the Pulmonary Ves-
  sels%__2Jte Aorta.—Its Divisions.—Its Termination.—The Cardiac Ar-
  fe).)^__Arteria Innominata.— Common Carotid.—Subclavian.—Arteries
  of the Upper Extremity.—The Intercostal Arteries.— The Phrenic.— Cce-
  liac Axis.—Superior Mesenteric—Other Abdominal Arteries  .   .  82

                        LECTURE XVIII.
                   the blood-vessels— Continued.
Common Iliac Arteries.—InternalIliacs.—External Iliacs.—Arteries of
  the Lower Extremities. — Veins  of the Head.— Of the Upper Extremity. 
Vlll
CONTENTS.
   —The great Veins of the Chest. — Veins of the Lower Extremities.—Por-
   tal Vein.—The Course of the Blood.........Page 89

                         LECTURE XIX.
                     CIRCULATION OF THE  BLOOD.
 Harvey's and Draper's Theories.—Affinity of Liquids for Tubes.—Princi-
  ple ofVenturi.— Causes of the Circulation in Systemic and Pulmonary
  Vessels differ.—Perfection  of Draper's Theory.— Course of various Ar-
   ticles to different Parts of the Body   ...........92

                         LECTURE XX.
                     SECRETION AND EXCRETION.
Formation of Secretions.—Structure  of Glands.—Action of Spheroidal
   Cells.—Filtration.—The Mammary Gland.—Its Changes and Diseases.
  — Colostrum. — Organs  of Excretion.—The Skin.— Composition and
  Function of the Skin.—Its Appendages.—Its  Glands.— Their Func-
  tions  ......................99

                         LECTURE XXI.
                     insensible perspiration.
Methods for determining its Quantity.—Diurnal and nocturnal Loss com-
  pared.—The Effect of Exercise—The Substances produced by the Disin-
  tegration of Muscle when in Action  escape by the Skin, and not by the
  Kidneys.—Relation of sensible and insensible Loss to each other.—Ef-
  fect of Ingestion of Food on insensible Loss.—Diurnal Variation in the
  Weight of the Body................104

                         LECTURE XXII.
                           RESPIRATION.
Divisions  of the Respiratory Apparatus.—The Larynx.—The Trachea.—
   The Bronchi.—The Air-cells.—The Lungs.—The  Divisions and Mem-
  branes  of the Lungs.—Rate of Respiration.—Action  of the Lungs-
  Stages  of Inspiration.—Diffusion of Gases.—Influence  of Membranes
  on Diffusion.................       -q g

                        LECTURE  XXIII.
                      respiration— Continued.
Second and third Stages depend on Diffusion of Gases.—Stages of Expira-
  tion.— Difference between inspired and expired Air.—Experiments on
  Respiration.—Object of Respiration.—Diseases affecting the Respiratory
  System.....................12£

                        LECTURE  XXIV.
                           ANIMAL HEAT.
Definition of Animal Heat.—Paine's Experiments~on the Temperature of
  Plants.—Cold and hot blooded Animals.—Relation of the Nervous Sys-
  tem to the Production  ofHeat.—Allotropic Condition of Carbon and
  other Elementary Substances.—Blushing explained.— Variations in the
  Temperature of the Body.—Temperatures that  can be endured by the
  Body.....................*131 
CONTENTS.
ix
                          LECTURE  XXV.
                        THE  URINARY SYSTEM.
 Position  and Descriptive Anatomy of the Organs forming the  Urinary
   System.—Microscopic Anatomy of the Kidney.—Portal Circulation of
   the Kidney.—Properties, Quantity, and Composition of Urine.— Classes
   of Food represented in  the Urine.—Function of the Malpighian Tufts
   and Convoluted Tubes.—Draper's Theory of the Method of Action of
   the Kidney.................page 135

                         LECTURE XXVI.
                       THE URINARY SECRETION.
 Rapidity of Excretion of deleterious Substances by the Kidneys.—Experi-
   ments  on the Origin of Urea. —Effect  of Diet and Exercise on the
   Amount of Urea excreted by the Kidneys.........140

                         LECTURE XXVII.
                       EXAMINATION OF URINE.
 Methods for determining  the Specific Gravity and Reaction of Urine.—
   Tests for an Excess  of  Urea.— Uric Acid.—Sulphates and Phosphates.
   —Tests for Albumen.— Origin of Albuminous Urine.—Tests for Blood
   in Urine.— Tests for Bile.—Pettenkofer1 s and Heller's Tests.—Diabetic
   Urine.—Moore's and Trammer's  Tests for  Sugar.—MauminVs Test.—
   TJie Fermentation Test.—Detection of Pus........150

                        LECTURE XXVIII.
                      THE LIVER  AND SPLEEN.
Functions of the Liver.—Functions  of the Spleen.—Relations of the Liver
   and Spleen to each other...............158

                         LECTURE XXIX.
                       THE NERVOUS SYSTEM.
Phosphorus the special Ingredient of Nervous Substance.—Production of
  Nervous Force.— Gray and white Nervous Substance.—The Ganglia de-
  scribed.— The Nerves described.—Divisions  of the Nervous Mechanism.
  — Tlie Nervous Systems of the Lower Animals.—The Sympathetic Sys-
  tem.—The Cerebrospinal System.— The  Brain. —The Spinal Cord.—
  Tlie Nerves...................166

                         LECTURE XXX.
     FUNCTIONS OF THE DIFFERENT PARTS OF  THE NERVOUS SYSTEM.
Function of the white Substance.—Rapidity of the  Conveyance of Impres-
  sions.—Simple Ganglia.—Registering Ganglia.—Influential Ganglia.—
  Relations and Functions of the Nerves, Spinal Cord, Ganglia at the Base
  of the Brain, and of the  Cerebrum to each other.—Functions of the Cer-
  ebellum.—Review of the Functions  of the Divisions of the Nervous Mech-
  anism   .....................175 
X
CONTENTS.
                         LECTURE XXXI.
                     THE  SPECIAL SENSES.
The Five Senses.—The Sense of Touch.—Its  Location.—The Skin de-
  scribed.—The Papilla?.—Acuteness of Sensation depends on the number
  of Papilla.—Sense of Touch corrects that of Vision.—Sense of Touch
  and of Temperature are distinct.—Localization of Touch in Lower Ani-
  mals ....................page 179

                        LECTURE XXXII.
                         TASTE AND SMELL.
Tissues composing the  Tongue.—Sensations appreciated by it—The Pa-
  pillce described.—Distribution of the Senses of Touch and Taste on the Or-
  gan.—Action of the Papilla} under the Influence of strong Flavors.—
  Deception of the  Organ of Taste.—Location of the Sense of Smell.—Di-
  visions_ of the  Nasal Cavity.—Distribution of the  Olfactory Nerve-
  Conditions essential to the proper Action of the Sense of Smell.—Inverse
  or subjective Sensations...............182

                       LECTURE XXXIII.
                    PROPERTIES OF SOUND.
General Properties of Waves.—Reflection  and Interference  of Waves.—
  Nature of Sound.—Analogy of Sound Waves to Water Waves.—Ac-
  tion of the Ear Trumpet.— Velocity of the Passage of Sound in various
  Media.—Effect of Variation of Density of Air on Velocity of Sound.
  —Non-conducting Power of Inelastic Bodies.—The Pitch and Quality
  of Notes....................  v&

                       LECTURE XXXIV.
                    ANATOMY OF THE  EAR.
Divisions of the Ear.—External Ear described.—Formation of Wax__
  The Tympanic Cavity and Membrane.— The Bones of the Ear.—The
  Eustachian Tube.— Openings in the Walls of the Tympanic Cavity —
  Muscles of the  Tympanic Cavity.—The Parts of the Internal Ear —
  The Vestibule described.—The Membranous Labyrinth.—The Perilymph
  and Endolxgmph.— Tlie Otoliths.—The Saccule and Utricle.—The Semi-
  circular Canals.—The Cochlea.—The Lamina Spiralis, Modiolus and
  Spiral  Canal—The Helicotrema.—Distribution of the Auditory  Nerve
  to the Internal Ear.............             lg()

                       LECTURE XXXV
                     HEARING AND  VOICE.
The Elements of Sound dealt with by the Ear.—Function of the Pinna
  and Auditory Canal—Function  of the Membrana  Tympani.—Func-
  tions of the Ossicles.—Of the Eustachian Tube.—Function of the Vesti-
  bule.—Of the Semicircular  Canals.—Of the Cochlea.—7he Destruction
  of Sounds in the Internal Ear.—Development of the Ear.__The Ear in
  the  Lower Animals. — Voice exists in Air-breathing Animals __Tlie
  Larynx described. —Vocal Cords.—Character of Song.—Of Whisvers
  — Of Voice or Speech............    J      y   ' 
CONTENTS.
XI
                        LECTURE XXXVI.
                  NATURE AND PROPERTIES OF LIGHT.
Theories regarding Light.—Existence, Nature, and Properties of the Ether.
  —Effect of Temperature on the Intensity of Light.— Compound Nature.
  of Light.—Action of Prisms.—Action of Surf aces and Media on Light.
  —Reflection, and the  Law which Governs  it. — Causes influencing the
  Intensity of the reflected Ray.— Transmission.—Absorption.—Interfer-
  ence—Interference and Prismatic Spectra  compared.—Refraction de-
  scribed.—Order of Refrangibility of Colors.—Theory of Coloration of
  Surfaces..................page 198

                       LECTURE XXXVII.
                     THE PROPERTIES  OF  LIGHT.
The three Forces in the Spectrum.—Presence  of Heat and its Point of
  Maximum  Intensity demonstrated.—Region of Maximum Intensity of
  Light.—Action  of Yellow Ray  on  Compounds  of Carbon.—Presence
  of Chemical Rays demonstrated.—Positive and negative Chemical Rays,
  their Points of Maximum Intensity.—Lenses classified.—Action of con-
  vex Lenses.— Of concave Lenses.— Causes of Variation in focal Distance
  of convex Lenses.—Spherical Aberration described.— Correction of Spher-
  ical Aberration.— Chromatic Aberration described, and the Methods of
  Correction.—Achromatic Lenses.—Penetrating Power of a Lens.—Rela-
  tion of penetrating Power to the Diameter of a Lens .   .  .  . .  203

                       LECTURE XXXVIII.
                    ANATOMY  OF  THE  EYE.
The Orbits.—Shape and Diameter of the Eyeball.—Its Tunics or Coats.
  — Tlie Sclerotic.— The Choroid.—The Black Pigment and  the Retina
  described.—Tlie Cornea and the three Humors.—Their relative Density.
  —The Lens described.— The Hyaloid Membrane and its Function.— The
  Iris, its Composition  and  Function.—The  Retina and Optic Chiasm.
  — The Appendages.—Position of the Muscles.— The Conjunctiva.—
  Tlie Lachrymal Gland and Nasal Duct.— The  Eyelids, Glands, and
  Lashes.....................207

                       LECTURE XXXIX.
                     THE ACTION OF  THE EYE.
The Function of the three Humors.— The Action of the Iris.—Adjustment
  for Difference of Distance of different Objects.—Method of Correction
  of Spherical Aberration. — Correction of Chromatic Aberration.—Ac-
  tion of black Surfaces on Light.—Action $f the Ocellus.—Action of the
  Compound Eye of a Fly.—Action of the Eye in the Higher Animals.—
  Action of the Muscles of the Eye.— Of the Lachrymal Ap>paratus.— Of
  the Lids, Lashes, and Eyebrows.—Longsightedness and Shortsightedness
  described. — Method for relieving them. — Cataract described. — Opera-
  tions for its Relief.—Strabismus.—Peculiarities of the Optical Apparatus
  in the Lower Animals.— Constitution of Areolar Tissue.—Adipose Tis-
  sue, its Formation, and Tenacity of certain  Positions.—Description of
  the Skin....................211 
Xll
CONTENTS.
                SECOND  DIVISION.

                    DYNAMIC PHYSIOLOGY.

                        LECTURE  XL.
                           REPRODUCTION.
Reproduction  of Plants. — Conditions requisite for Germination and
  Growth.—Reproduction of Animals.— Organs of Reproduction in Ovi-
  parous and Viviparous Animals.—Menstruation.— Corpus Luteum.—
  Semen, its Composition and Properties.—Impregnation.—Nourishment
  of Foetus.—The Placenta.— Quickening.—Miscarriage.—Parturition.—
  Change in Respiratory Function at Birth......Page 217

                         LECTURE XLI.
                    THE COURSE OF HUMAN  LIFE.
The five Periods in the Life of an Individual.—Size of the new-born In-
  fant.—Rate  of Growth.—Average Height  of Adults.—Maxima and
  Minima of Height.— Weight at Birth.—Average Weight of Adults.—
  Period of maximum Weight. — First Attempts at articulate Speech. —
  Relation of the vegetative  and intellectual Powers to each other.—Evi-
  dences of their Influence on each other. — Decline of Intellectuality.—
  Average Duration of Life.—Mortality at different Periods.—Influence
  of Sex and Stature on Mortality.—Instances of great Longevity.—Ap-
  proach of Death.—The Fades Hippocratica. — Interstitial Death.—
  Period of Repair.—Sleep.—Amount of Sleep required at different Peri-
  ods of Life.— Order in which Sleep subverts  the Senses   .  .  .   .  222

                         LECTURE XLII.
 INFLUENCE OF  EXTERNAL AGENTS ON THE PHYSICAL AND INTELLECTUAL
                        CONDITION OF MAN.
Distribution of Plants.— Conditions which Control their geographical Po-
  sition.—Nature of the Boundary-lines formed.—Influence of Ocean Cur-
  rents on Climate. — Distribution of Animals. — Influence  of Physical
  Agents on Man.—Theories regarding the Origin of the Human Race.—
  Explanation of the Production of Races.—Variation in the Color of Men.
  —Measurements of the Skull.—The Facial Angle......227
                  THIRD  DIVISION.

                           HYGIENE.
                           >
                      LECTURE  XLIII.
                               FOOD.
Divisions of Hygiene.— Conditions essential to a healthy State of the Di-
  gestive Apparatus.—Number of Meals per Diem, and the Times at which
  they should be taken.—Adaptation of Food to the Age of the Individual.
  — Varieties of Milk.—Food of Infants.—Influence of  the Diet of the
  Mother  on the Character of her Milk.—Selection of a Nurse.—Frangi-
  pane.—Butter.— Cheese.—Age at which solid Food should be given to a
  Child   .  . '...................231 
CONTENTS.
Xlll
                       LECTURE  XLIV.
                          OF ANIMAL  FOOD.
Conditions that produce Scurvy.—Prevention of Scurvy.—Extraordinary
  Articles employed as Food by the Ancients and Moderns.—Pecidiarities
  of the Flesh of young Animals.—Effect of the Food on the Flesh of an
  Animal.—Effect of Season.—The Fumet.—Age  at which the Ox and
  Sheep reach Perfection.—Effect of Castration on the Flesh of Animals.—
  Nutritive Properties of lean and fat Meat.—Proper Time and Method of
  Slaughtering.—Nutritive Qualities of the Flesh  of Birds.— Castration
  and Cramming of Birds.—Effect of Cooking on the Digestibility of Eggs.
  —Poisoning by unwholesome Flesh.—Fish and Reptiles used as Food.
  — Caviare.— The Oyster and other Shellfish......Page 235

                         LECTURE XLV.
                      OF VEGETABLE  FOOD.
Vegetable Food less wholesome than Animal Food.—Bread best adapted
  to Dyspeptics.—Indigestible Character of Pastry.—Rusted or Ergot Rye.
  — Prejudices against the Use of Oatmeal. — Use  of Cornmeal. — Pella-
  gra.—Polenta.— Use of Legumens.—Indigestibility of Nuts.—Effect of
  Cooking on Digestibility of Potatoes.— Use of raw and  cooked Cabbage.
  —Salads.—Sugar does not injure the  Teeth.— Concentrated Solutions of
  Sugar most Digestible.— Classification of Condiments, and Effect of in-
  sufficient Supply of Salt.—Anchovy and Bloater Pastes.— Use and Abuse
  of Vinegar.—The aromatic Condiments.—Effect  of Climate on the Na-
  ture of Diet.—Effect of Occupation on Diet.—Idiosyncrasies.—Effect of
  Irregularity in the Evacuation of Fmces.........242

                         LECTURE  XLVI.
                      FLUIDS  USED  AS  DRINK.
Causes that produce  Thirst.— Temperature  at which Water should be em-
  ployed as Drink.— Use of Ice.—Natural Waters.—Differences between
  Rain and Spring Water.—Effects of Lime-water  on the  System.—Effect
  of Salines on  rapidity  of Absorption of Water. — Goitre. — Materials
  suitable for making Water-pipes and  Tanks.—Protection of Lead Pipes.
  —Precautions to be employed in the Use of Lead Pipes.—Purification
  of Water by Filtration and Distillation.— Objections to  the Use of sweet
  Drinks.— Toast-water.— Gruel.—Properties of Tea and Coffee.—Intro-
  duction of Tea.— Classification and Composition  of Tea.—Effects of the
  Abuse of Tea.—Introduction of Coffee.—Preparation for Use.— Choco-
  late.—Soda-water.................247

                        LECTURE XLVII.
                ALCOHOLIC STIMULANTS AND  TOBACCO.
Classification of fermented Liquors. — Times  at which alcoholic  Fluids
  should be taken. — Effects of the Abuse of alcoholic Drinks. — Prepara-
  tions of Wines.—Must.—Imperfection of our Grapes.— Composition of
  Wine.—Its Bouquet.—Effect of Age.— Causes that Influence its intoxi-
  cating Power.—Port.—Sacks.—Sweet Wines.—Malt Liquors.—Liqueurs.
  —Liquors: Brandy, Whisky, Gin, Rum.
Tobacco its Introduction.—Forms in which it  is used.—Effects on the ol- 
xiv
CONTENTS.
  factory Nerve.—Principles in Tobacco.—Effects of excessive Smoking.—
  Training...........'.......Page 252

                        LECTURE XLVIII.
               HYGIENE OF THE  RESPIRATORY SYSTEM.
Changes impressed on the Air by Animals.—The Action of Plants.—The
  Black Hole at Calcutta.—The Black Assize at Oxford.—Effects of Car-
  bonic Acid on the System.—Inhalation of carbureted Hydrogen.—Fire-
  damp.— Choke-damp.—Effects  of sulphureted Hydrogen. — The Action
  of Chlorine on  noxious Vapors.—Principles of Ventilation.—Methods
  of Warming by open Fires, by  Stoves, and by Furnaces, with the Ad-
  vantages and Disadvantages of each.— Objections to the Use of Steam-
  coils in Rooms.—Advantages of the Steam-heating Furnace   .  .   257

                        LECTURE XLIX.
                    DISINFECTANTS AND MALARIA.  •
Substances employed as Disinfectants.—The Peloponnesian Plague.—Ac-
  tion of Charcoal.—Malaria or Miasma.— Circumstances under which, it
  is produced with greatest Virulence and Rapidity.—Is not the Result of
  Animal or Vegetable Decomposition alone. — Evils attending the close
  Proximity of Trees to a Dwelling.—Selection of a Building Site.—Rela-
  tive Power of dry and moist Air to convey Malarial and other Emana-
  tions.— Explanation of the Appearance of Malarial Fevers  on  high
  Ground.—Means for warding off' the Access of Malaria.—Effect  of
  Change of Air  on the  System.—Action of  Winds.—Time at which a
  Consumptive should Travel..............262

                          LECTURE L.
                       HYGIENE  OF THE SKIN.
Effect of sudden Changes of Temperature on the Mortality Lists.—Symp-
  toms of approaching Death from  Cold.—Southern Nations resist Cold
  better than Northern.— Time at  which it is best to go into the  cold Air
  from a heated Room.—Effect of Moisture on the System.—Effect of
  desiccated Air on the Mucous Membrane of the Lungs.'— Great solvent
  Action of moist Air on Emanations.—Application  of Heat to frozen
  Limbs.— Chilblain.—Effect of Climate on Nations.—Effects  of Light
  and Electricity on the Body.— Conveyance of Miasmatic Emanations
  by damp Air.—Effects of Winds  on endemic and epidemic Diseases   267

                          LECTURE LI.

             hygiene of the skin, Continued.—bathing.
Conditions essential for the proper Conduction  of the Action of the  Skin.
  — The Roman Thermos.—Action of pure Water on the Skin.— Use of
  Soap. — Abuse of Soap.— Cold Plunge-bath. — The  Chill or  Shock.—
  Use of the Cold Bath for Infants.— Conditions of the System  in which
  Cold Baths should not be used.—Tepid Baths.—Adaptation  of Tepid
  Baths to various Constitutions.— Warm Baths and their Action.—Hot
  Baths and their Action.—Flagellation.—Shampooing.—Turkish Bath.
  —Sea Bathing.—Effects of the  long-continued Application of Water to
  the Skin.—Evil Consequences  attending the sudden Stoppage of the Ac-
  tion of the Skin..................271 
CONTENTS.
XV
                          LECTURE LII.
                  HYGIENE of the skin.—CLOTHING.
Materials employed in the Manufacture of Clothing. — Experiments of
  Davy on the conducting Power of various Textures.—Influence of Pack-
  ing on the conducting Power.—Summer and Winter Clothing.— Use of
  Flannel.—Exemption of the ancient Romans from Malaria.— Captain
  Murray's Experiments with Flannel.— Use of Flannel by the Aged, and
  Infirm. — Use of Stockings. — Changing of Under-clothing. — Clothing
  should be well aired.—Scotch Method of airing Clothing.—The  Cut or
  Shape  of the Clothing.—Adaptation of the Shape to the Climate.— Use
  of Corsets.—Experiments of Dr. Stark on the absorptive Power of Tex-
  tures of different Colors.............Page 277

                          LECTURE  LIII.
     HYGIENE OF THE MUSCULAR, OSSEOUS, AND NERVOUS  SYSTEMS.
Exercise  necessary to the proper Maintenance of the Muscular and Nerv-
  ous Systems.—Forms of Exercise. — Active and Passive  Exercise.—
  Walking. — Leaping. — Running. — Dancing.— Fencing. — Boxing.—
  Wrestling.—Horseback Exercise.— Sailing.— Driving.— Passive Move-
  ments  of different Limbs.—Amount of Exercise required by an Adult.
  —Incompatibility  of Labor and Mental Activity. — Conditions requi-
  site for the proper Development of Bone  .....   ....   282

                        LECTURE  LIV.
                           PROPHYLACTICS.
History of Jenner's Discovery of Vaccination.— Quarantine.—Fomites.—
  Conditions that favor the spread of Cholera and the Fevers.—Purifica-
  tion of Streets and Public Places.—Purification of Private and Tenement
  Houses.—Personal Prophylaxis.— Insanity. — Cancer.—Phthisis.—Ef-
  fects of Intermarriages.— Conclusion..........286 
 
LIST   OF   ILLUSTRATIONS.
                                   Fagc
Cells showing Nuclei..........................  3
  "     "      "  ..........................  3
Reproduction of Cells by Section..........  4
     "          "      Granulation....  5
Mural Tissue....................................  5
Varieties of Conferva, showing the Shape
  of Cells and Nuclei..........................  5
Yellow Fibrous Tissue...*....................  6
Section of Bone magnified 50 Diameters,
  showing Haversian Canals................  11
Section of Bone  magnified 250 Diame-
  ters, showing Lacunas and Canaliculi..  11
Cartilage ossifying, magnified 10 Diame-
  ters..............................................  12
The Skeleton....................................  14
Base of the Skull, showing  the Occipital
  Bone and Foramen Magnum.............  16
The Sphenoid Bone............................  16
The Ethmoid Bone............................  16
Lateral View of Skull........................  16
Temporal Bone.................................  16
Parietal Bone, inner Surface................  17
Superior  Maxillary, outer and inner Sur-
  face.............................................  17
Inferior Maxillary..............................  17
The Nasal Bones...............................  17
The Palate Bones..............................  18
The Malar Bone................................  18
The Vomer......................................  18
Cervical, Lumbar, and Dorsal Vertebrae..  18
The Vertebral Column........................  19
The Os Innominatum.........................  20
The Sacrum and  Coccyx.....................  20
The Scapula.....................................  21
The Clavicle.....................................  21
The Humerus...................................  21
The Femur.......................................  22
The Foot.........................................  23
White Fibrous Tissue magnified 300 Di-
  ameters ........................................  24
Lever of  1st Class..............................  24
    "     2d Class..............................  24
         3d Class...............................  24
Blood-vessels of Muscular Tissue..........  26
Rectangular Cells of Voluntary Muscle..  26
Striped Muscular Fibre.......................  26
Involuntary Muscle Cells.....................  26
Unstriped Muscle..............................  26
The Muscular Svstem.........................  28
  "      "     "  "   .........................  31
The Digestive Tract...........................  34
The Hydra.......................................  35
Parts composing Teeth........................  36
                                   Page
Incisor Teeth..........................  .......  37
Canine Teeth..................................  37
Bicuspid and Molar Teeth..................  37
Human Lower Jaw...........................  38
Jaw of Rat......................................  38
Section of Stomach..........................  39
Muscular Bands of Stomach...............  40
Mucous Membrane of Stomach magni-
  fied 70 Diameters..........................  40
Sections of Stomach Follicles magnified
  150 Diameters..............................  41
The Duodenum...............................  42
Section of Wall of Ileum magnified 50
  Diameters...................................  43
Parotid Gland.................................  45
The Liver.......................................  47
The Pancreas..................................  48
Brunner's Glands.............................  49
Follicles of  Lieberkuhn.....................  49
Peyer's Plates.................................  49
Stomachs of Ruminant......................  60
     "     Kangaroo......................  61
Digestive Tract of common Fowl.........  62
Elevation of a wetting Liquid.............  64
Depression of a non-wetting Liquid......  64
The Endosmometer..........................  65
Villus showing Termination of the Lac-
  teal Tube....................................  68
Villus showing Blood-vessels..............  68
  "      "    External Cylindroid Epi-
  thelium.......................................  69
Thoracic Duct.................................  69
Chyle Corpuscles..............................  70
Human Blood Discs  magnified 500 Di-
  ameters.......................................  74
The Heart......................................  77
Heart of Dugong..............................  78
Right Side of Human Heart...............  79
Left      "      "      "  ...............  80
Valves of the Heart..........................  81
The Circulatory System.....................  84
Carotid Arteries..............................  86
Superior Mesenteric Artery.................  88
Motion in a Capillary Tube................  93
Principle of Venturi.........................  93
Capillary Circulation in a Frog's Foot..  94
Section of Mammary Gland................ 100
Colostral Corpuscles of Milk............... 100
Transplantation of Tissues................. 101
Skin of Palm magnified 20 Diameters .. 102
Section of Human Hair..................... 102
Section  of  Skin  magnified  10 Diame-
  ters............................................ 103 
XV111
LIST OF  ILLUSTRATIONS.
                                     Page
Sudoriparous Gland magnified 20 Diam-
  eters........................................  103
Side View of Larynx........................  118
Back View of Larynx.......................  118
Traohea, Bronchi, and Bronchial Tubes 119
Capillary Bronchi and  Air-cells  of  a
  Lobule................................____  119
Capillary Blood-vessels of Air-cells.....  120
Relative Position of the Heart and Lungs 120
Mechanism of Respiratory Apparatus....  122
Simple Diffusion.............................  122
Diffusion of Gases through porous Bar-
  riers...........................................  123
Diffusion through poreless Structures ...  123
    "    against Pressure..................  124
The Respiratory Machine..................  126
Air-sac of Fish................................  132
Lung of Reptile............................... 132
Lung of Frog.................................. 133
Section of Kidney.............................  136
Diagram of Convoluted Tube and Tuft.. 136
Convoluted Tubes and Blood-vessels ....  137
Tuft and Convoluted  Tube.................  137
Diagram of Malpighian Circulation.....  137
The Urinometer............................... 150
The Fermentation Test...................... 157
Nerve-cells, 350 Diameters.................  167
Bipolar Nerve-cell, 350 Diameters........ 167
Multipolar Nerve-cell, 200 Diameters... 168
Ganglion of a Mouse......................... 168
Nervous System of Mollusca............... 169
    "       "     Radiata................ 169
    "       "     Articulata............. 169
The Sympathetic System................... 170
Exterior of Brain............................. 171
The Cerebrum................................. 172
Section of the Cerebrum..................... 172
Base of the Brain............................. 173
The Cerebellum............................... 173
Sections  of Spinal Cord..................... 174
The Spinal Cord.............................. 175
Registering Ganglion........................ 176
                                     Pago
Influential Ganglion.......................... 177
Simple Papilla?, 35 Diameters............. 180
Compound Papilla?, 60 Diameters........ 180
The Tongue................................... 183
Division's of the Nasal Cavity............. 184
Distribution of Olfactory on Septum of
  Nose  ......................................... 184
Distribution of Olfactory on outer Wall
  of Nasal Cavity............................. 184
The Pinna...................................... 189
External, Middle, and Internal Ear...... 189
The Ossicles and Muscles................... 190
Labyrinth magnified two Diameters...... 191
Exterior of the three Semicircular Ca-
  nals and  Cochlea.......................... 191
Membranous Labyrinth of the Canal.... 191
Section  of the Cochlea...................... 192
Distribution of Cochlear Nerve............ 192
Spiracle of Insect............................. 197
The Vocal Cords............................. 197
Position of the Eyeball in  the  Orbital
  Cavity........................................ 207
Blood-vessels of the Choroid Coat....... 208
      "        "      "     "   ....... 208
The Eyeball.................................... 208
View  of the Crystalline Lens............... 209
  "     "        "      "  ............... 209
  "     "        "      "  ............... 209
Fibres of the Lens............................ 209
Vitreous. Humor, showing the Hyaloid
  Membrane.................................... 209
Muscles of the Eyeball....................... 210
Cellular Tissue........'........................ 215
Adipose Tissue................................. 216
Hydra budding................................ 218
Uterus and Appendages..................... 219
Corpora Lutea................................. 220
The Testis...................................... 220
Skull  of European............................ 229
   "    Negro................................ 229
   "    Chimpanzee........................ 229
   "    Orang................................ 229 
ANATOMY, PHYSIOLOGY, AND  HYGIENE.
            FIRST DIVISION.
ANATOMY AND STATICAL PHYSIOLOGY.
                       LECTURE I.
                     INTRODUCTION.
 Theories regarding the Nature of Life.—The Food introduced into the
  System is combustible.—The Substances voided from the Body are all
  burnt or oxidized.—The Methods to be employed in the Examination
  of the Structure and Function of Organisms endowed with Life.— Cells
  enter into the Composition of all Tissues and Creatures.
  What is Life ?  The philosophers of past times tell us that
 it is an  inborn, inherent power, by which plants  and animals
 resist for a time the  decay and  final oxidation or destruction
 to which they must sooner or later submit.
  The physiologist of the present day demonstrates, by experi-
 ments which we can  not refute,  that the oxidation of the ma-
 terials introduced into the system as food is one of the essen-
 tial conditions for the maintenance of life.
  Unless we breathe  air, or some gas containing oxygen, death
 is in a few moments the inevitable result.  Without water, we
 may for  a short time exist,  tortured by an agonizing thirst.
 Without food, life may be prolonged for two or three  weeks,
 or even  a month; but  starvation will have so weakened the
 powers of the sufferer that he is either reduced to a condition
 of hopeless delirium, or the hasty, careless introduction of food
 into the  stomach will produce a  shock from which the system
 can not recover.
  If we submit  the substances  employed as food to  chemical
 analysis, we find that they are, without exception, composed of
 carbon and hydrogen, to such an extent as to furnish a consid-
 erable amount of heat when burned in the air; they are there-
  What was the old theory regarding life ?  What is the modern idea of life ?  What is the
composition of food?
                            A 
2
theory of life.
fore combustible.  If we examine in a similar manner the ma-
terials ejected from the body, we find that they have been
more  or less perfectly oxidized in the  system, and are incapa-
ble of being burned.
  From such facts as these, we conclude that the essential con-
dition for the proper maintenance of life in man and animals is
a sufficient supply of air, water, and food.   We may  regard
ourselves  as machines, in which power is produced by the oxi-
dation of a certain quantity of combustible material;  and as in
a steam-engine power is generated by the combustion  in the
furnaces  of the boiler, so in man the oxidation of nerve and
muscle are absolutely necessary for the production of thought
and action.
  The decay and death  of the tissues are essential to the exist-
ence of the individual.   The human machine wears away by
use, and  man  can not live but by the destruction and repro-
duction of the cells of which the body is composed.
  Life, therefore, is not a condition  of stability, a power pos-
sessed by plants  and animals of resisting the great physical
laws of nature; it is produced by them, and is subject to their
domination.  The wonderful enigma of our  existence has been
beautifully expressed by one of the greatest of modern physi-
ologists, who says: " An organism, no matter of what grade it
may be, is only a temporary form, which myriads of particles
passing through a determinate career give rise to.   It  is like
the flame of a lamp, which presents for a long time  the same
aspect, being ceaselessly fed as it ceaselessly  wastes away."
  As we  seek to  explain the ordinary phenomena with which
we come in contact by observation and experiment, so in phys-
iology we should, as far as is  expedient, endeavor to examine
into the operations of the organs and glands of the body by a
careful study of their structure and action.  If we find that cer-
tain articles are conveyed to a manufactory, and in due  course
of time other materials of greater value are produced, we inves-
tigate the nature  of the  machinery and the materials used, and
have no difficulty in understanding the processes employed.  So
with any organ or gland, if we carefully examine its  structure,
the materials conveyed  to it and those which it produces, we
sooner or later arrive at a rational  explanation  of  its  action
and function.
  Applying a similar system of investigation to living crea-

 What is the nature of the substances voided from the system ?  What substances are re-
quired for the proper maintenance of life ? 
anatomy of cells.
3
tures and the tissues composing them, we find, on submitting
them to the test of the microscope, that they are  constructed
< )f cells, and fibres which  originate in a cell, which is the sim-
plest form of living organism, and invariably consists of certain
parts, without regard to  its function or the  structure it may
compose.
                        LECTURE  II.
                            cells.
Parts composing a Cell.— Vegetable and Animal Cells.—All living Things
  originate in and are composed of Cells.—Reproduction of Cells.—For-
  mation of Tissues from  Cells. — Secreting and protecting Cells.— Cells
  enter into the Composition of Liquids.—Nutrition of Cells.—Definitions
  of Anatomy, Physiology, and Hygiene.
   If the dust-like pollen from a flower is placed under the mi-
croscope, we find that it is composed of small spheroidal or el-
liptical bodies.   In such organic  atoms there resides  a power
which can fructify  female  flowers, and initiate all the wonder-
ful phenomena which  result  in the production  of a perfect
plant.
   This minute microscopic body is called a cell.   It consists of
an external membrane or cell  wall, which incloses the cell con-
tents.   These may be either fluid or solid, depending upon the
character of the  cell.  The defined separate mass contained in
the interior is called  the nucleus; in it the changes to which
                                          Fig. 2.
Cells showing Nuclei.
  What is the simplest form of living organism ?  What is the appearance of the pollen of
flowers under the microscope ? What are the parts of a cell ? What is a nucleus ? 
4
reproduction of  cells.
 the cell is liable usually commence.   Sometimes the nucleus it-
 self contains a germinal spot, to which the name of nucleolus is
 given.
   The simplest example of animal as well as vegetable life is
 also a cell.   Of this we may satisfy ourselves by placing under
 the microscope  some of the green slimy material called con-
 ferva, which grows  in  stagnant water.   At first we  only see
 the elongated cells which form the fibres of the plant;  but as
 we examine their various-shaped nuclei, we are surprised from
 time to time by circular bodies which dash across the field of
 the instrument with great rapidity, and seem not only to pos-
 sess the power of voluntary motion, but also  the capability of
 directing their course into any desired path.   These  are mon-
 ads, or cells endowed with voluntary  motion; they  therefore
 belong to the animal kingdom, for the possession of this power
 is the true distinguishing mark between a plant and an animal.
   Examining the germ from which  any given animal  origin-
 ates, we find that it also is a nucleated cell.   Since, therefore,
 all living things, whether they belong to the animal or vegeta-
 ble kingdom, originate  in and are born from cells, we  must re-
 gard  these  minute  organisms with peculiar interest, and en-
 deavor to familiarize ourselves with their various forms, and
 their methods of reproduction.
   An excellent illustration of a simple cell is offered by an
 egg, in which the shell represents the cell wall, the white  the
 cell content, the yolk the nucleus, and the germinal spot of the
 yolk the nucleolus.
   In the eggs of some of the lower forms of animal life we can
 at our leisure watch the development, growth, and final pro-
                       duction of the  perfect creature  almost
                       as easily as we can trace similar oper-
             w IH^ ®  ations in vegetable  cells.  The pro-
                       cesses  in both  are the same, but since
                       the vegetable cells offer fewer obstruc-
                       tions to the use of the microscope in
                       the study of their  reproduction,  we
                       shall deal chiefly with them.
                        # Cells are multiplied or reproduced
                       either by  section or  by granulation.
                       In  the first  the  cell wall gradually
  seproduction of ceiis by section.   doubles in toward the nucleus, so as
  What is conferva?  What is its composition?  What are monads? What  is the essen
tial difference between a plant and an animal ?  What is the origin of a plant or an ani
mal ?  Illustrate the parts of a cell by those of an egg ? How are cells reproduced ?
Fig. 3.
 
tissues are composed of cells.
5
Fig. 4.
Fig. 5
                    Reproduction of Cells by Granulation.

to give the cell a dumb-bell form, which becomes  by degrees
more and more complete, until it is finally divided through the
nucleus and two perfect cells produced.  In reproduction by
granulation the movement commences in the nucleus.  It breaks
up into exceedingly minute grains,  which form  nucleoli, that
gradually  enlarge  until they  fill
the  nucleus,  which  soon disap-
pears, and the cell  seems to  be
filled with nuclei.  The wall then
bursts, and the  nuclei, being  set
free, become new, perfect cells.
   In order to form tissues, cells
are sometimes arranged as in Fig.
5, presenting  an appearance  simi-
lar to that of a wall built of cut
stone.  Such  are called mural tis-
sues.  Sometimes  cells are  elon-
gated and placed end to end, as in
the fibres  of  the yeast plant  and
conferva.  In other instances the cells become greatly elonga-
                             Fig. 6.
Mural Tissue.
Varieties of Conferva showing the shape of the Cells and Nuclei.
Describe reproduction by section and granulation.  How do cells form tissues ? 
6
divisions of physiology.
ted, as in in voluntary muscle and fibrous tissues.  If the cells
                           retain  their  spherical figure  the
                           organs formed produce secretions,
                           while in the skin and all structures
                           intended  merely  for  protection,
                           they dry up and become  scale-like.
                             Not only are tissues  composed
                           of cells, but  all animal  fluids, as
                           for example blood, contain one or
                           more  special  forms  of   cells by
                           which we  can  often detect their
                           presence.  The description of these,
                           as well as of the  cells of special
                           tissues, as muscle and nerve, must
       Yellow fibrous Tissue.        ^      '         ._        tit
                           be reserved until we reach the dis-
cussion of such fluids and organs.
  In order that a simple organism like a cell  shall  exist and
grow, it must be supplied with proper nutriment.  The tissues
of men and  animals, being formed of cells, must therefore be
furnished with the  materials required for their growth and
development.
  To satisfy the stern necessity that Nature has thus impressed
on all animals, that they should seek their food, she has' merci-
fully provided them with bodies constructed in such a manner
as to be capable of motion, and possess the power of convert-
ing various articles of food into a nutritious fluid, on which tis-
sues may feed.
  The study of the body is divided into two distinct branches,
Anatomy and Physiology.  The  first deals with its structure;
the second treats of the  functions of the  organs of which it is
composed.   To these we may add a third, Hygiene, which ex-
amines into the conditions most favorable for the maintenance
of perfect health.
  Physiology is, by Professor J. W. Draper, divided into  Static
and Dynamic Physiology.   The first relates to man as an indi-
vidual, and discusses the functions  of the different organs of
the body.  The second  treats of man in his  social  state, and
deals with nations or masses of men, examining into their rise
progress, and influence on each other.   The advantages attend-
ing this division  are so self-evident that we shall adopt it
without discussion.
  What is the difference between a secreting and a protecting cell ?  Into what branches is
the study of the body divided? What is Anatomy? What is Physiology?   What is Hv-
giene ?  What are the divisions of Physiology ? 
TISSUES AND ORGANS  OF THE  BODY.
t
  In  describing the various organs of the body, wTe shall first
explain the anatomical structure of each, and then pass to the
consideration of its function, so that the structure and function
may be connected with each other in the mind of the student,
and more readily recollected.
                       LECTURE III.
                ANATOMY  OF THE HUMAN  BODY.
The Tissues and Fluids composing the Body.—Divisions of the Body.—
  Cavities of the  Head, their Contents.— Cavities of the Trunk and their
  Contents.—Subdivisions of the Extremities.— The Skeleton, its Uses.—
  Composition  of Bone, and variations in the Proportions of its Ingredi-
  ents.— Diseases of Bone.— Importance of Bones in  certain Manufac-
  tures.—Microscopic Appearance  of Bone.—Membranes of Bone.—Di-
  vision and Classification of Bones.
  The body is  composed of solid tissues or organs, and fluids.
They are,
  1st. Bone, which supports the other tissues and organs, and
gives a fixed  figure and form.
  2d. Ligament and  cartilage connect the bones and form a
skeleton, possessed of joints and capable of motion.
  3d. Muscle, endowed with the property of contractility, gives
motion to the body.
  4th. Organs  of nutrition, divided into  digestive,  absorptive,
and circulatory.
  5th. Organs of secretion and excretion, as the lungs and kid-
neys.
  6th. Nervous tissue regulates the action of the muscles and
all  the organs of the body.
  7th. Special senses—vision, hearing, smell, taste, and touch—
by  which the system is brought in communication with exter-
nal objects.
  8 th. Areolar  or connective tissue.
  9th. The skin and its appendages.
  10th. The organs of reproduction.
  The fluids of the system are,
  1st. Blood, which may be  arterial or venous.  The first  is
bright red, owing to its containing oxygen; while venous blood
is dark blue, and contains carbonic acid.
 What are the tissues of the body ?  What are the uses of bone ? of ligament and carti-
lage ? of muscle ?  What are the organs of nutrition ?  Give examples of the organs of ex-
cretion. What is the function of nervous  tissue ?  Name the special senses. What are
the fluids of the body ? What is the difference between arterial and venous blood ? 
8
FLUIDS OF  THE BODY.
  2d. Chyme and chyle.   The first is a tawny yellow color, and
formed during digestion in the stomach.  The second is milky,
and is found in the small intestines and lacteals.
  3d. Lymph, a colorless  fluid, contained in minute vessels call-
ed lymphatics.   It represents the excess of nutriment conveyed
to various parts of the body.
  4th. Bile, a yellow or  greenish fluid secreted by the  liver.
It sometimes becomes condensed, and forms hard masses called
gall-stones, which cause excruciating pain as they pass into the
intestine.
  5th. Digestive juices, consisting  of saliva, gastric, pancreatic,
and intestinal juices.
  6th. Excretions and secretions, such as urine, sweat, milk.
  For the sake of convenience, the body is  described under six
divisions—head, trunk, and four extremities.
  The head contains the following cavities:  1st. The cranial,
which accommodates the brain; 2d. The buccal, in  which the
tongue and teeth are placed; 3d and 4th. The orbital, contain-
ing the eyes ;  and, 5th. The nasal, inclosing the organ  of smell.
  The trunk is divided into three cavities:  1st. The  thoracic,
which has yielding bony walls, and contains the heart, lungs,
great  blood-vessels,  and air-tubes;  2d. The abdominal, sur-
rounded by soft, yielding muscular walls,  and separated from
the thoracic by  a muscle  called the diaphragm.
  The abdominal cavity contains the liver, which lies immedi-
ately under the diaphragm, and chiefly on the right side; the
stomach, under  the liver and  on  the left side;  the  spleen, on
the left of the stomach;  the kidneys, in the back of the cavity;
the intestines, in front and  on  the sides; the  pancreas, beneath
and behind the  stomach.
  The pelvic cavity, inclosed by unyielding bony walls, con-
tains the  bladder in  the  male, and the bladder  and uterus in
the female.
  The extremities are divided into the upper and lower.   The
subdivisions  of the  upper  extremities are the  shoulder, arm,
forearm, and hand.   Those of the lower extremity are the hip,
thigh, leg, and foot.
  With these preliminary remarks regarding the general char-
  What is the difference between chyme and chyle, and where are they found?  What is
lymph, and in what vessels is it found? What is bile? How are gall-stones formed?
What are the digestive juices?  What are the divisions of the body? What cavities are
found in the head ? What do they contain ?  Name the cavities in the trunk.  What are
the contents of the thoracic—of the abdominal—of the pelvic cavity?  What are the subdi-
visions of the  upper extremity ? of the lower extremity ? 
                 FUNCTION OF THE SKELETON.               9

acters of the tissues and fluids of the body, we now pass to the
stud)' of                                            ,
                        THE SKELETON.
   All animals are provided with a more or less perfect skele-
ton, the  object of which is to furnish a support for the various
soft tissues and organs, or to protect them from injury and vio-
lence.  In the lower orders it is often placed on the outside of
the body,  and is the  only protection the creature has against
the attacks of its numerous enemies.   An excellent illustration
of this arrangement is afforded by the oyster, which is furnish-
ed with  a hard shell or exterior skeleton, the chief use of which
is to  protect the soft tissues from injury.
   Passing a little  higher in the scale, we find that the lobster
and such creatures  are endowed with a far  greater freedom of
motion than the oyster;  consequently, though their skeletons
are on the outside of the body, they are built on  a different
plan; the  various  parts are lighter, and  arranged so as to fur-
nish  a  system of jointed levers and  supports, by  which the
creature can at its  will transport itself from  one place to anoth-
er, and avoid its  enemies, or obtain  the  food necessary for its
proper nourishment.
   Though a certain degree of facility of motion can be reached
by means  of an exterior skeleton, yet it is almost incompatible
with  such  perfect freedom as is required in the higher animals ;
consequently we find  that in fishes,  reptiles, birds, and beasts,
the skeleton is in the  interior of the body.   It is every where
covered  by soft tissues, and is arranged so as to furnish levers
for the  organs of locomotion, or form cavities in  which the
more delicate organs,  as  the brain, heart, lungs, and digestive
apparatus, may be properly protected from injury.
   In  man  and animals, the separate  pieces of which the skele-
ton is composed are called hones.  These differ in their form so
as to. fulfill the purposes for which they are intended, but in
chemical composition  they show but slight variation.
                          Analysis of Bone.
     Cartilage or gluten......................... 32.17)  a    i      •     „,»
     Blood-vessels................................  113 J-Animal or organic....... 33.30
     Phosphate oflime........................... 51.041
     Carbonate of lime........................... 11.30
    Fluoride of calcium........................  2.00 > Mineral or inorganic... 66.70
    Phosphate of magnesia....................  1.16 |
    Soda salts.....................................  1.20J                ______
_________________________________________100.00_______________________100.00
  What is the object of the skeleton?  Is it always placed in the interior of the body?
What are its uses in the higher animals ?  What are bones ?  What is the chemical compo-
sition of bone ? 
10
CHEMICAL  COMPOSITION OF BONE.
  Examining the above analysis by Berzelius, we find that we
may regard bone  as  being composed of animal  and mineral
substances in the proportion  of  one third of the former  to
about two thirds of the latter.  This, although true in regard
to bones of adults, is not the case in children and old people.
In the former the proportion of animal material is  far greater
than one third, and consequently in infancy and early child-
hood the bones of the lower extremities are apt to bend if they
are used too soon, since they are  not sufficiently consolidated
to support the weight of the body.   The age  at which they
may with safety be used depends  to a great  extent on the diet
and digestive powers  of the child.   If the  food  is  not nutri-
tious, or the constitution of the infant is poor, the  proportion
of animal material in the bones will be too great, and they will
be flexible and bend, producing the deformity called rickets  or
bandy-legs, in which not  only the bones of the legs, but also
the ribs and pelvic bones, may be deformed  to such an extent
as to interfere seriously with the proper performance of the
functions of the body.
  In the osseous tissues of old people, on the contrary, the pro-
portion of mineral matter is in excess; consequently their bones
are very  brittle, and break readily, often being  fractured by
such slight violence  as making a false  step while walking.
Not only does age affect the composition of bone, but  some
bones always contain a greater proportion of mineral substance
than others.  For example, that in  which the organ of hear-
ing is  situated possesses such a large proportion  of inorganic
substance as to have received the name of the petrous, or stone-
like bone.  With these exceptions,  we may regard bone  as
having a uniform  composition, represented by the analysis  of
Rerzelius.  ,
  The presence of animal substances in bones may  be  readily
demonstrated by burning them  in a vessel from which the air
is excluded.  Treated in this manner, they turn black; the car-
bon of the animal substance remaining, while the hydrogen
and oxygen are driven off.  To the black residue  obtained the
name of animal or bone charcoal is given; it is of great value
in certain manufactures, owing to the property it possesses  of
bleaching various organic colors.  It is extensively  used in re-
fining sugar; the crude dark brown sugar being dissolved  in
  What are the proportions of animal and mineral substances in the bones of adults ?  What
are the proportions in children ?  What is meant by rickets ?  What is the composition of
bone in old persons?  What bone contains the greatest amount of mineral substance?
What is animal charcoal ?  How is it prepared ?  What are its uses ? 
BONE UNDER THE MICROSCOPE.              11
water to form a  sirup, which is passed through a column of
coarsely - powdered bone  charcoal, twelve  or fifteen  feet  in
length, and escapes below as a colorless fluid, which is evapo-
rated and crystallized in masses, and returned to the market in
the form of crushed and white sugar.
   If the  bones are burnt  in  a current of air, they finally be-
come perfectly white; the mineral material, consisting chiefly
of phosphate  of lime, alone remaining.   The bone-earth pro-
duced in this  manner is in the form of powder used to  make
cupels  for refining gold and silver; it is also employed as a
fertilizer.
   A very pretty  method for  separating the mineral from the
animal materials  is to place a bone in dilute hydrochloric acid,
composed of one part of acid to ten or fifteen of water.  In the
course  of a few days  the acid dissolves  all the mineral sub-
stance, leaving the animal material, which preserves the origin-
al figure  of the bone, but is so flexible that it may be  readily
tied in  a knot.   The composi-
tion and growth  of bones may
be  satisfactorily studied by the
examination of their sections un-
der  the  microscope.  With  a
suitable power the  appearance
in Fig. 8 is obtained.  The large
openings are  called the haver-
sian canals, through which the
Fig. S.
Fig. 9.
^"^i^fe^-'
Section of Bone magnified 250 Diameters, showing
       Lacunae and Canaliculi.
  Section of Bone magnified 50 Diameters, showing
           Haversian Canals.

larger  blood-vessels  pass  to
nourish the bone.
   In Fig. 9 the fine lines  are
called  canaliculi.   They trav-
erse the  tissue in every direc-
tion, and convey the fluid por-
tions of the blood to the lacu-
nae or bone cells which are scat-
tered throughout the fabric, and
 How is the refining of sugar conducted? For what purpose is bone-ash employed?
Which ingredient of bone is soluble in acid? What is the appearance of bone under the
microscope ?  What are the haversian canals ?  What are the lacuna? ? 
12
CLASSIFICATION OF BONES.
             f^ 10.               are represented in Fig. 9 by the
                                black masses.
                                  The development  of bone
                                first  begins by the formation
                                of a  mass  of cartilage which
                                takes on the  figure  of  the
                     sioShA...*,.....-   "bona  In this a variable num-
   „ t.           .. a 1ftTV         ber of spots of true bone srrad-
   Cartilage ossifying, magnified 10 Diameters.       ,..    -1        .         O
                                ually appear which are centres
of ossification.   Around these the mineral matter is deposited
until it extends throughout the mass, and it becomes  perfectly
consolidated, and possesses the rigidity necessary to  adapt it
to the purpose for which it is intended.
   All bones are covered exteriorly by a membrane, in which
the blood-vessels subdivide and form  minute arteries, which en-
ter the haversian canals to nourish the osseous tissue.   To it
the name of periosteum is given; and so necessary is this mem-
brane to the well-being of the osseous tissue, that any injury to
it results sooner or later in the death of the bone.
   For convenience of description, bones are divided into three
classes, long, flat, and irregular.   The  first are found in the ex-
tremities.  They consist of a shaft composed of hard, dense tis-
sue, usually hollow, and filled with marrow or fat.  The cavity
is cylindrical in shape, and lined with a membrane similar to
the periosteum. . It is called the endosteum; its duties are the
same as those of the external membrane.   The ends of the long
bones are smooth, and enlarged to furnish surfaces  suitable
for the formation of firm joints.  The canal of the shaft does
not extend to the  ends of the  bone,  but  disappears in  a spe-
cies of cellular structure, which is better adapted to  the con-
ditions which are to be fulfilled by the extremities.
   The flat and irregular bones usually inclose cavities, and are
found in the skull, pelvis, and  other  regions.   They are com-
posed of two layers of hard, dense tissue, the intermediate space
being occupied by spongy tissue, thus combining strength with
lightness, as is  also the case with the  ends of long bones.
   Bone, like the other tissues of the body, is subject to a num-
ber of diseases, such  as cancer  and inflammation, but  the spe-
cial trouble is  the liability to fracture.  When a bone is bro-
ken, if the fractured extremities are kept properly in juxtaposi-
  How does the development of bone commence ?  What is the periosteum ? What are the
three classes of bones ? Describe a long bone. What is the endosteum ? How far does
the canal of a long bone extend ?  What is the difference in structure between the shaft and
extremities of a long bone ? How are flat bones constructed ? 
 
Fig. 11.
03 
THE  SKELETON.
15
tion, they unite in a few days by the formation of cartilage, in
which the mineral matter is gradually deposited, until, after the
lapse of a few weeks, the juncture becomes more solid and
dense than any other part.
  In the Hunterian Museum there are many singular examples
of diseased skulls, some being  an inch thick, and  others pos-
sessing osseous growths from various parts.   In one which be-
longed to a prize-fighter, there are osseous projections from the
rim of the orbits about three inches in length, which were pro-
duced by injuries received in various encounters.
Skull.

Trunk
                       LECTURE IV.
               BONES  COMPOSING THE SKELETON.
  Number of Bones in the Body.—Bones of the Trunk.—Pelvic Bones.
   The number  of bones in the body varies at different ages,
but in the adult there are 238.  They may be conveniently
studied under the following divisions :
                  (Cranial.........................................................  8
             ......... "[Face.............................................................. 14
                  (Neck, thorax, and abdomen................................. 50
             ......... (Pelvis.............................................................  4
     Upper extremities -!!.1 5  > .......................................................... 64
     Lower extremities-jr'?1 > ........................!...........................><... 60
     Internal ear................................................................................  6
     Teeth........................................................................................ 32
                                                     238
   The bones  of the skull are divided into those of the cranium,
which inclose the cavity in which the brain is placed, and  those
of the face.   The latter are very irregular, while the former are
true flat bones.
   The cranial bones are the frontal, occipital, sphenoid, ethmoid,
two temporal, and two parietal.
   The frontal forms the forehead and the  roof of the orbital,
cavities, in which the eyes are placed.
   The occipital  {Fig. 12)  forms  the back of the head and
part of the base of the skull.  The large opening is the fora-
men magnum, through which the spinal cord passes.
   The sphenoid {Fig. 13) bears some resemblance to a bat, be-
  How is the fracture of bones repaired ?  How many bones are there in the body ? How'
many in each division ?  Name the cranial bones. Describe the frontal, occipital, sphenoid
bones. 
16
BONES  OF THE  CRANIUM.
Fig. 12.
Fig. 13.
Base of the Skull, showing the Occipital Bone
      and Foramen Magnum.
The Sphenoid.
Fig. 14.
ing very irregular in form.  It articulates with nearly all the
                   bones  of the skull, and forms the keystone
                   to the  arches of the cranium.
                     The ethmoid {Fig. 14) lies between the
                   cranium and the face.   It is composed of a
                   number of very thin plates  of bone, rolled
                   into a  mass of scroll-work, and covered by
                   mucous membrane, in which the filaments
                   of the  olfactory nerve terminate to form the
                   organ of smell.
The Ethmoid Bone.
Fisr. 15.
Fig. 16.
Lateral view of Skull.
Temporal Bone.
  The temporal bones aid in forming the base and sides of the
skull.  They are described as being composed of three parts:
the mastoid, thick and cellular; the squamous, very thin and
brittle; and the petrous, dense, hard, pyramidal in shape, and
hollowed out in the interior into irregular cavities, which con-
tain the  small auditory bones.  The sense of hearing is lodged
in this part, the waves of sound reaching the interior cavities
through  an opening on the  outside, called the meatus  audito-
Describe the ethmoid and temporal bones. 
BONES OF THE FACE.
17
Fig. IT.
rius externus, while the auditory nerve gains access to the same
cavities through an opening near the apex of the petrous part
called the meatus internus.   The projecting arm of bone is
called the zygoma, and the smooth gle-
noid cavity at its origin articulates with
the lower jaw.
  The parietal bones are quadrilateral
in shape, and form the sides and roof of
the skull.  The inner surface is grooved
by  arteries  {Fig. IT), the rupture  of  |I
which is one of the serious consequences
of fracture of the skull.
  The bones of the face are three max-
illary, two nasal, two palate, two malar,
two lachrymal, two turbinated, and one
                   Fig. 18.
Parietal Bone, inner Surface.
vomer.
Fig. 19.
Superior Maxillary,
 outer Surface.
Superior Maxillary,
 inner Surface.
Inferior Maxillary.
  There are two bones in the upper, and one in the lower jaw.
The upper maxillaries form the floor of the orbital cavities, and
present a number  of projections, the most  important of which
are the alveolar process, in which the teeth are fixed; the pal-
atal, which forms part of the hard palate; and the nasal, which
forms the side of the nasal cavity.  The body of the superior
maxillary presents a large cavity called the antrum or cave, the
object of which is to give resonance  to the voice.
The lower maxillary bone consists of a horizontal
and ascending portion; the ends are smooth, to ar-
ticulate with the temporal bone, while the teeth
are fixed into the alveolar process of the horizontal
portion.
  The nasal bones form the upper hard part of the
Fig. 20.
The Nasal Bones.
nose.
 What is the zygoma ?  What is the name of the articular cavity ?  What are the three
divisions of the  temporal bone?  What is the shape and position of the parietal bones?
What are the bones of the face ? Describe the upper maxillary bones. What is the an-
trum ?  Describe the lower maxillary bone.  Where are the nasal bones ?
                             B 
18               DIVISIONS OF  THE VERTEBRAE.

  The palate bones are shaped like  the letter L.   They assist
in forming the hard palate.
  The 7nalars form the  outer part of the orbital cavities, and
the upper hard part of the cheeks.
  The Ictchrymals are small and very thin.   They form a por-
tion of the inner side of the  orbits, and are in contact with the
nasal processes of the upper maxillary.
  The turbinated bones are in the nasal cavity, and attached to
the ethmoid, in order to increase the  surface on which the olfac-
tory nerve is spread.
Fig. 21.               Fig. 22.                Fig. 23.
The Palate Bones.          The Malar Bone.          The Vomer.
  The vomer is shaped like a plow-share, and divides the na-
sal  cavity into two equal lateral portions.
  The bones of the trunk are the os hyoides, twenty-four verte-
bras, twenty-four ribs, the sternum, two ossa innominata, the sa-
crum, and the coccyx.
  The os hyoides is situated in  the throat, at the base of the
tongue.
  The vertebrce are divided into three classes, seven  cervical,
twelve dorsal, and five lumbar.  The cervical are the smallest,
                             Fig. 24.
Cervical Vertebra.         Dorsal Vertebra.           Lumbar Vertebra.
and are in the neck;  the lumbar are the largest, and form the

  Describe the palate bones.  Where are the malar bones ?  Describe the lachrymal bones;
the turbinated bones ; the vomer, flame the bones of the trunk.  Where is the os hyoides ?
What are the divisions of the vertebrae, and how many in each ?  In what part of the verte-
bral column are the largest bones found ? 
THE VERTEBRAL COLUMN.
19
Fig. 25.
small of the back; the dorsal aid in forming the back  of the
chest, and they all possess facets on the  sides, by which they
articulate with the ribs.
  Each vertebra consists of a body, and incloses an opening
through which the spinal cord passes.  The ring of bone of
each vertebra that forms this  opening terminates
posteriorly in a sharp  projection called the spi-
nous  process.  The vertebras  are  arranged one
over another, and joined by ligaments and an in-
tervening disc of elastic cartilage, so as to form a
column, marked in the back by the row of rough
projecting spinous processes.   Between the verte-
bras there are openings through which the spinal
nerves pass.
  Considered as  a unit, the  vertebral  column
forms  a series of  curves: one in the neck, the
convexity  of which looks forward; one in the
chest, the  convexity looking backward; one  in
the abdomen, with the convexity forward; and
one in the pelvis, formed by the sacrum and coc-
cyx, with the convexity backward.
  These  curves,  and numerous  vertebras with
their connecting cartilages, give to  the  column
great elasticity, which protects the brain  from in-
jury by the sudden jars it would  otherwise be
subjected to in jumping and such violent move-
ments.   The lower part of the column is support-
ed by the bones of the pelvis and legs, and in its
turn gives support to the organs of the trunk, up-
per extremities, and head.
  The ribs  are about  half an inch in width, and
curved upon themselves so as to form an arc of a
circle.    One  of the  extremities is  round and
smooth, to articulate with one or two vertebras;
the other is rough, and gives attachment to a car-
tilage, by means of which the ribs are connected
to the sternum.   The under  edge of each rib is
marked by  a groove, in which the arteries of the
chest lie, and are  protected from violence so per-  x'
fectly that they are not readily reached in any ordinary wound
The Vertebral Column.
 Describe a vertebra.  How are the vertebras connected ? Describe the curves of the
vertebral column.  How is the lower part of the vertebral column supported ?  Describe
the ribs.  How do their extremities differ ? How are the arteries of the chest protected ? 
20
THE PELVIC BONES.
Fig. 26.
The Os Innominatum.
by a knife.  The seven upper ribs on each side are called true,
and the five lower false ribs.
  The sternum  or breast-bone is flat, and connected with the
ribs  by costal cartilages; it articulates  above with the  clavi-
                           cles.
                             The ossa  innominata, so called
                           from their want of resemblance to
                           any other known natural object,
                           are composed in infancy of three
                           parts, which become consolidated
                           into one  bone  in adults.   They
                           are called the ilium, ischium, and
                           pubes.  The first is the flaring por-
                           tion, which  forms the  hip bone;
                           the second is the lowest part, and
                           terminates below in a rough mass
                           called the tuberosity, which  bears
                           the weight  of the body when  in
the sitting position; the third is the anterior portion.
  The pubic bones unite in front to  form  an arch called the
pubic arch, which is much more obtuse in  the female than in
the male.  The  three divisions  of the innominatum meet in a
smooth circular depression called the acetabulum, which accom-
              modates the head of the  femur to form the hip
              joint.
                 The sacrum is triangular in shape, and artic-
               ulates  laterally  with  the  ossa  innominata—
               above with  the  last lumbar vertebra, and be-
               low with the coccyx.   It forms  the posterior
               wall of the pelvic cavity, and is  perforated on
               its anterior and  posterior surfaces with a num-
               ber of foramina or openings, through which the
               terminal divisions of the  spinal cord pass.
   The sacrum.       ^phe C0CCyX [s a small triangular bone attach-
ed to the tip of the sacrum; it is the termination of the  verte-
bral column.
  The ossa innominata, sacrum,  and coccyx form  the pelvis, the
shape  of which varies  with the sex.  In  the male it is cup-
shaped, while in the female the iliac bones flare out so  as  to
give it more the form of a saucer, and the cavity is wider in all
its dimensions, and not so deep  as in the male.
  How many true and false ribs ?  Describe the sternum. Describe the ossa innominata.
What  are the divisions of the os innominatum ? What is the tuberosity ? What is the
acetabulum ? Describe the sacrum'. Describe the coccyx.  What is the pelvis ?
Fig. 27.
 
BONES  OF THE UPPER  EXTREMITY.            21
Fig. 28.
Fig. 29.
The Clavicle.
Fig. 30.
                       LECTURE  V.
                 the skeleton—Continued.
Bones of the Upper Extremity.—Bones of the Lower Extremity.— Varie-
  ties  of Joints.—Tissues ichich enter into the Composition of Joints.—
  Joints and Bones form Levers.—Diseases and Wounds of Joints.
  The bones of the upper extremities are the scapula, clavicle,
hmnerus,  radius, ulna, eight carpal, five metacarpal, and four-
                  teen phalanges.
                   The scapida, or  shoulder-blade, is held in
                 position by muscles which are  attached to the
                 vertebras and ribs  so
                 that it is  movable.
                 It  is  triangular  in
                 shape, the upper and
                 outer angle furnish-
                 ing an articular surface called the
                 glenoid cavity, which receives the
                 head of the arm bone to form the
                 shoulder-joint.
                   The clavicle is shaped like the
letter f.   It is  commonly  known  as the  collar
bone: its  duty is  to keep the shoulder-joint out-
ward and backward.  It is the first bone in the
body that is perfectly ossified.
  The hmnerus, or bone of the arm, is a long bone,
as are  all the  rest  of the bones of the upper  ex-
tremity except the carpal.   The  upper part is call-
ed the  head; it articulates with the  glenoid cav-
ity of the scapula.   On the outer side  of the head
there is a rough  mass  called the  tuberosity, to
which some of the muscles that move the arm are
attached.   The lower end of the bone is grooved,
forming a  hinge-like joint with the bones  of the
fore-arm.
  The radius and ulna are the bones  of the fore-
       The ulna forms the  elbow-joint, while the
The Scapula.
arm.
The Humerus.
 What are the bones of the upper extremity ?  Describe the scapula;  the clavicle; the
humerus.  With what cavity does the humerus articulate ? What are the bones of the fore-
arm ?  Which joint does the ulna chiefly form ? 
22
BONES  OF THE LOWER EXTREMITY.
radius forms the wrist.   They are placed side by side, and ar-
ranged so that the radius can move to a certain extent around
the ulna, and give  to the hand the movement of rotation it
possesses.
  The bones of the wrist, or carpal bones, are eight in number,
and placed in two rows, the first containing the scaphoid, sem-
ilunar, cuneiform, end pisiform; the second the trapezium, tra-
pezoides, magnum, and unciform.
  The metacarpal bones are five in number, one for each finger;
they articulate  with the second row of carpal bones, and form
the palm of the  hand.
  There are fourteen phalanges, three for each finger and two
for the thumb.
  The lower extremity  is composed of the femur, patella, tibia,
fibula, seven tarsal  five metatarsal bones, and fourteen pha-
                              langes.  They all belong to the
                              order of long bones.
                                The femur, or thigh bone, has
                              the  head set  on the  shaft  by
                              means  of a neck, which forms
                              an angle that varies with  the
                              age  of the individual.  In  old
                              age  the angle is nearly ninety
                              degrees,  and consequently  the
                              neck of the femur supports  the
                              weight of the body in the most
                              disadvantageous manner, and is
                              very liable to undergo fracture.
                              The upper part of the bone is
                              furnished with a strong, rough
                              tuberosity  for  the  attachment
                              of muscles.   The lower end is
                              expanded so  as  to form two
                              condyles,  separated by a deep
                              groove; it  articulates with  the
                              tibia to form  the knee-joint.
                                The  tibia and fibula form  the
                              leg.  They are  closely bound
together, and are not movable like the bones of the fore-arm.

  Which does the radius form ?    How many bones are there in the carpus ? Name
them.  How many metacarpal bones are there ?  How many phalanges are there ? Name
the bones of the lower extremity.  Describe the femur. How does the angle of the  shaft
and neck vary with age ?  What are the bones of the leg? What are their relations to the
knee and ankle joints ?
The Femur. 
COMPOSITION OF  JOINTS.
23
They terminate below in processes called malleoli, which give
great firmness to the ankle-joint.
   The patella lies in front of and protects the knee-joint.   It
is inclosed in the tendon of the muscles of the thigh, and ena-
bles them to act to greater advantage.
   The tarsal  bones are  arranged in two  rows.   The first con-
sists of the astragalus,  which ar-
ticulates  with the bones of the
leg to  form the ankle, and the os
calcis, which forms the heel.   The
second  row  is  composed of the
cuboid, scaphoid, and three cunei-
form bones.
   The metatarsus consists of five
bones, one  for  each toe.   They
form the sole  of the foot.
   There  are  fourteen phalanges,
three for each toe, except the large
toe, which has two.
   The bones  of the internal ear
will be  described in connection
with the sense of hearing.
   The teeth  belong properly to
the function  of  digestion, and will be studied in connection
with it.

                         THE JOINTS.
   Bones are united together  so as to form either immovable or
movable joints.   The best example of the first class is furnish-
ed by  the skull.  In it  the various bones are dovetailed into
each other along their edges, to form perfectly unyielding joints
called  sutures, which may be broken, and the  bones obtained
separately, by filling the  cranial cavity with well-dried  peas,
and  adding water, when the peas  swell  and force  the  bones
apart.   The joints of the second class vary greatly  in the de-
gree of mobility the}' possess, from the sliding motion of the
bones of the carpus on each other, to the  hinge-like motion of
the knee or elbow, or the almost universal mobility of the ball
and socket joints of the  hip and shoulder.
   The tissues which enter into  the formation of a movable
joint are, 1st.  The smooth articular ends  of the bones;  2d. A
  Describe the patella.  Name the tarsal bones. How many metatarsal bones and pha-
langes are there?  Describe the two varieties of joints, and give examples of each.  What
are sutures ?  What tissues enter into the formation of a joint ?
 
24
CLASSIFICATION OF JOINTS.
Fig. 33.
covering of very dense polished cartilage, which gives a slight
degree of elasticity, and aids in reducing the friction;  3d. Liga-
ments, which bind the bones together; 4th. The synovial mem-
brane  or sac, which contains  the fluid, and lies between the
cartilages of the joint, its  object being to reduce the friction ;
5th. Muscles, which  move  the  bones; and, 6th. Nerves, which
govern and regulate the actions of the muscles.
                             The osseous tissue  has already
                           been described.   Cartilage consists
                           of cells and fibrous tissue.   Liga-
  jk liSpl ^ \l^^k •   me11^  is composed of white fibrous
 Ml 1               H \   tissue, in which the cells have be-
                           come  elongated into mere lines; it
                           is  admirably  adapted to the pur-
                           pose for which it is employed.  The
                           synovial sac is also composed of
                           fibrous tissue, and lined with se-
                           rous membrane.   These are the es-
                           sential tissues of the joint; the
                           muscles and nerves are auxiliary.
                           We may therefore pass at  once to
the study of the joints, and then take up the examination of
the muscular and nervous tissues.
  All the long bones, and  some of the bones  of the other class-
es, are used in the construction of movable joints, serving either
as levers to move the body, or to carry on some process neces-
sary to the well-being of the system, as, for example, mastica-
tion.   There are three classes  of levers, all of which are repre-
White Fibrous Tissue, magnified
     300 Diameters.
Fig. 34.
Fig. 35.
Fig. 36.
Lever of 1st Class.
Lever of 2d Class
Lever of 3d Class.
sented in the body.   In the first class, the fulcrum is between
the power and the resistance; in the  second, the resistance is
 What is cartilage ?  Describe cartilage and ligament.  Describe the synovial sac and
fluid.  What are the varieties of levers ? 
COMPOSITION OF  MUSCLE.
25
in the centre; and in the third the power is  in the  middle.
In the systems of levers in the body, the fulcrum is the joint
and the power the muscle.   In throwing the head backward
we have an example of a lever of the first class; in raising the
body on tip-toe we have  an example of the second; and in
flexing the  fore-arm on the  arm we have  an example of the
third.
   Joints, like the other parts of the body, are liable to inflam-
mation.  When the ligaments are involved, it is called rheuma-
tism; this sometimes passes into a  chronic state, and is exceed-
ingly painful.  When the synovial membrane and cartilages
are involved, it is called white swelling, which is very apt to
terminate in a union of the bones and entire loss of the use of
the joint.  Sometimes small hard cartilages are formed in the
knee-joint, which slip between the  ends of the bones in walk-
ing, and produce the most excruciating pain.  Wounds of the
large joints, though they may  appear to be insignificant, are
very dangerous, and often cause death if the joint is opened to
the access of air.
                       LECTURE VI.
                   THE MUSCULAR SYSTEM.
The Muscular Tissue.—Microscopic Characters of voluntary and involun-
  tary Muscle Cells.— Tendons and their Position.—Divisions of Muscles.
  —Muscles of the Head and Neck.— Of the Upper Extremities.— Of the
  Trunk.— Of the Lower Extremities.

  The muscular tissue forms the bulk of the body; it is very
freely supplied with blood-vessels, and is of a deep red color in
the majority of animals, forming the lean meat or flesh—an ex-
cellent example being  the beef prepared  for sale in  the mar-
kets.  There are, however, exceptions to the general law, as in
the breasts of fowls, where it is white; this is supposed to be
in part due to the fact that  the pectoral muscles in such crea-
tures are not used to any great extent, and they therefore un-
dergo a fatty degeneration, and  lose their color.   The chemical
elements entering into the composition of this tissue  are car-
bon, hydrogen, oxygen, nitrogen, and sulphur; it is consequently
a nitrogenized body; it also possesses the power of contractility,
which is in part due to the manner in which it is constructed.
  What diseases affect joints ?  What are false cartilages ? What wounds of joints are
most dangerous ? What is the color of  muscle ? Why are the pectoral muscles of fowls
white ?  What chemical elements enter into the formation of muscle ? 
26      VOLUNTARY
AND INVOLUNTARY
MUSCLE CELLS.
Fig. 37.
Fig. 38.
Fig. 39.
Blood-vessels of Muscular Tissue.
Rectangular Cells of Voluntary Muscle.   Striped Muscular Fibre.
  Muscles may be classified under two heads:  the voluntary,
controlled by the will, as the muscles  of the  extremities ;  and
the involuntary, which act independently of the will, and even
without its knowledge,  as the muscular, coat of the stomach
and intestines.  The microscopic characters of the two varie-
ties are very different, voluntary muscle fibre being composed
of rectangular-shaped cells, placed end to end like the  cells of
conferva, and having a  rectangular nucleus.  The  fibres are
Fig. 40.
Involuntary Muscle Cells.
Fig. 41.
Unstriped Muscle.
formed into bundles, the arrange-
ment of the cells being such that
the nuclei are side by  side, and
form  line's.  Owing to this pe-
culiarity, it is often called striped
muscle.
  Involuntary fibre, on the  con-
trary, is composed  of elongated
cells, and there is no special sys-
tem in their arrangement;  conse-
quently, the nuclei do  not form
lines,  and it passes  under the
designation of unstriped muscle.
  The  force generated by the
  What is the difference between voluntary and involuntary muscles, and the cells compos-
ing them ? 
 
Fig  42.
 
MUSCLES OF HEAD  AND NECK.
29
contraction of muscular fibre is applied to the bones through
the intervention of an inelastic band of white fibrous tissue
called tendon.   One extremity of each fibre of a muscle usual-
ly arises directly from a bone, and the other terminates in the
tendon, which passes over one or more joints, and is attached
to another bone.  The tendon  is sometimes on the side of the
muscle, giving an appearance similar to that afforded by an or-
dinary  quill  pen.  These  are  called penniform.   Sometimes
fibres branch off from both sides of the tendon;  such are bipen-
niform.  In  some  muscles the fibres radiate from  a central
point, as in the iris of the eye ; these are called radiate.
  It is  impossible, within the  circumscribed limits of a text-
book, to describe all the muscles of the body;  but it is desira-
ble that every educated person should know something regard-
ing the names, position,  and shape of the  external muscles,
which  are situated immediately under  the skin,  and give to
the body  its beautiful contour and gracefully curved outline.
Painters and sculptors endeavor to represent them in various
works of  art, and every one takes an honest pride in develop-
ing and exhibiting a graceful muscular limb.
  The voluntary muscles may be described under  six divisions,
those of the head and neck, of the trunk, and the  four extrem
ities.   The ends of the muscles are spoken of as the origin and
insertion; the first is the portion in which the muscular fibres
are attached  directly to the bone;  the  insertion is the tendin-
ous end;  it is usually attached to the most movable bone.
  The muscles of the head and neck are the occipito-frontalis,
which lies immediately under the hairy scalp, extending from
the eyebrows to the back of the head.   Some persons possess
the power of moving this  muscle to a very considerable degree.
Two muscles, the temporal and masseter, arise from the tem-
poral fossa on the  side of the skull, and are inserted into the
ascending portion of the  lower jaw; they give motion to the
jaw, and are employed in the act  of mastication.   The cheeks
are formed of a muscle called the buccinator.   The muscle that
forms the lips is the orbicularis oris; it is employed in the act
of kissing, and consists of a number of circular bands that pass
around the mouth.  A similar circular muscle surrounds each
of the  eyes; it is  called  the  orbicularis palpebrarum.   The
great muscle that forms the nape of the neck is the trapezius;
  How is the force generated by muscles applied?  What is a penniform muscle—bipenni-
form—radiate ? Where are the largest muscles found ?  What are the divisions of mus-
cles ?  What is the origin of a muscle ?  What is its insertion ?  What are the muscles of
the head and neck ? Describe their actions. 
30          MUSCLES OF EXTREMITIES AND TRUNK.

it throws the head back; it is opposed by the sternocleido-
mastoid muscle, which bends the head forward on the chest.
When both sets of muscles act together, the head is kept firm-
ly fixed, as in carrying burdens.   There are many other mus-
cles in the head and neck, but these are the  most prominent,
and can  be traced in the majority of paintings or pieces of
sculpture.
  The muscles of the  upper extremities are the deltoid, tri-
angular shaped, and covering the shoulder; it  raises the  arm
from the side of the body to a horizontal position.  The trape-
zius aids in carrying it up to the vertical line.   The biceps, or
large muscle on the front of the arm, flexes the fore-arm on the
arm, and makes the preparation for striking a blow.   The tri-
ceps extends the fore-arm on the arm; it is on the back of the
humerus, and is used in delivering a blow.  The muscles of
the fore-arm are all  small, and do not give any special marks
or contours, except in persons in whom the muscular system is
exceedingly well developed; we must therefore leave the de-
scription of them to more extended works on anatomy.
  The muscles of the  trunk are the pectoralis  major  and mi-
nor.   They form the breasts, and, taking their origin from the
sternum  and inner  edges of the upper  ribs, are inserted into
the humerus; they are employed in  folding the arms  across
the chest.  Opposed in action to the pectorals is the latissimus
dor si, which, arising from the lower two thirds of the vertebral
column,  is inserted into the humerus, and throws the  arms
backward; they are greatly developed by the exercise of row-
ing.   The  muscle which extends from the lower part of the
sternum  to the pelvis is called the rectus abdominalis.  As is
the case with nearly all the muscles of which  we have treated,
it is one  of a pair; with its fellow it forms the anterior wall of
the abdomen;  it is  divided transversely into three portions,
the divisions being well marked only in very  muscular indi-
viduals.  The muscles  which complete the walls of the abdom-
inal cavity are  the  obliquus externus, obliquus internus, and
transversalis.  The fibres of these muscles are arranged, as their
names indicate, so as to cross each other, and produce in their
action an equable pressure on the organs contained in the ab-
dominal  cavity. In addition to  these, there are a great num-
ber of small muscles  in the back and between the ribs;  the lat-
ter are called intercostals; they aid in carrying on respiration.

  What are the muscles of the upper extremity ? Describe their actions.' Name the mus-
cles of the trunk. Describe their actions. 
Fig. 43.
 
 
MUSCLES OF  THE LOWER EXTREMITY.
33
  The muscles of the lower extremities  are, 1st. Those which
form the buttocks; they are called the glutei muscles.  They
are arranged in three layers, viz., external, middle, and internal.
Though these muscles exist in the lower animals, they are de-
veloped to a far greater extent in man, giving to him the pow-
er of retaining the  erect position.   Opposed to the glutei are
the iliac and psoas  muscles, which arise from the abdominal
surface  of  the vertebral column,  and, passing over the  pubic
bone, are inserted into the femur.  The  great muscles of the
thigh are the rectus femoris, which passes from the iliac bone
to the patella; the vastus  externus and vastus internus, which
take their  origin from the outer and inner surfaces of the fe-
mur, and  are inserted into the patella;  they extend the leg
on  the  thigh.  The muscle  which runs  obliquely across the
thigh, from the iliac bone to the inner edge of the tibia, is call-
ed the sartorius, or tailors' muscle, since it is employed in bend-
ing the lower extremities into the position assumed by persons
of that  trade while  at their work.  The muscles that are  in-
serted into the patella are in reality attached to the tibia, for
a strong ligament, about two inches in length, passes from the
lower edge of the patella, and is attached to a rough surface on
the anterior edge of the tibia.  The largest muscle on the back
of the thigh is the biceps ; it flexes the  leg on the thigh, and,
since it takes its origin in part from the ischium, also aids in
extending  the thigh on the trunk.   The  muscles of the leg are
the gastrocnemius, on the back of the  leg, giving it its full-
ness ; it extends the foot  on the leg, and raises  the body in
walking.   The tibialis anticus, and other smaller muscles  on
the front  of the  leg, flex the foot on the leg, and oppose the
gastrocnemius.
  The involuntary muscles will be described together with the
organs and functions with  which they are connected.
       What are the muscles of the lower extremity ? Describe their actions.
                             c 
34
THE  DIGESTIVE TRACT.
LECTURE  VII.
ORGANS OF NUTRITION.
Fig. 44.
The Digestive Tract.
Divisions of tlie Nutritive Process.—
  Divisions of the Digestive Aj'para-
  tus.—Distinctive Characters of Mu-
  cous and Serous Membranes.— Tin-
  Composition and Classification of
  the Teeth.—Description  of the Buc-
  cal Cavity.— The  Pharynx.—The
  Oesophagus. — The Stomach. — The
  four Serous Membranes.—The Mu-
  cous Coat of the Stomach.—The Fol-
  licles of the Stomach.— The Ends of
  the Stomach.
  Nutrition is divided into three
distinct processes, viz., digestion,
absorption, and  circulation.   We
shall commence with  the study
of digestion, and the description
of the anatomy of the  apparatus
by which it is accomplished.
  1, the  tongue  ; 2, pharynx ; 3,
oesophagus; 4, soft palate ;  5, sec-
tion  of larynx  ; 6, hard palate;
7, epiglottis; 8, thyroid cartilage;
9, spinal cord;  10, bodies of ver-
tebras ;  11,12, spinous  processes;
13, cardiac end of the  stomach;
14, splenic extremity ;  15, pyloric
end; 16,  greater  curvature; 17,
lesser curvature ; 18, the pyloric
valve;  19, first  portion of duode-
num;   20,  second portion;  21,
third portion;  22, gall bladder;
23, cystic duct;  24, hepatic duct;
25, ductus  communis choledo-
chus; 26, its entrance into duo-
denum; 27, pancreatic duct; 28,
29,jejunum; 30,ileum; 31,open-
What are the divisions of the nutritive process ? 
MUCOUS AND  SEROUS MEMBRANES.
35
 ing of ileum into large intestine; 32, ileo-colic valve; 33, ileo-
 cecal  valve;  34, cascum; 35, appendix  vermiformis; S% as-
 cending colon; 37, transverse colon;  38, descending colon; 39,
 sigmoid flexure; 40, rectum;  41, anus.
   For convenience of description, the digestive apparatus may
 be considered under six  divisions:  1st. The mouth  or buccal
 cavity; 2d. Pharynx; 3d. (Esophagus or gullet; 4th. Stomach;
 5th. Intestines; 6th. Glands.
   The buccal cavity is closed in front
 by the lips, which  are composed of
 muscle (orbicularis  oris), and cover-
 ed by mucous membrane.  This mem-
 brane has  a composition similar to
 that  of the skin; it  secretes a glairy
 fluid called mucus,  and lines  the di-
 gestive  apparatus   throughout  its
 whole length, and may be described
 as being continuous  with the skin.
 In some of the lowTer orders, as  the
 polypes and hydra, it  is not only
 continuous with the skin, but it also
 can at any time, by merely inverting
 the creature, be made to take on the
 action of the skin, while the skin be-
 comes at the same time the digestive
 surface.
   Mucous membrane is generally in
 the form of a tube, and communicates
 freely with the external air.   When
 it is inflamed, the diseased condition
 terminates in the production  of pus
 or matter.   Serous membrane, on the
 contrary, is always in the form of a  closed sac, and does not
 communicate with the external air.   When inflamed, the dis-
 ease usually results in the formation of adhesions  which unite
 the surfaces of the sac  together.  Pus  is very rarely formed,
 and when  it is, it is  a very unfavorable symptom, usually re-
 sulting in the cleatfi of the patient.
   Immediately within the lips are the gums, composed of the
 alveolar processes of the maxillary bones, covered by thick mu-
  What are the divisions of the digestive apparatus ?  Describe the buccal cavity.  What
are the properties of mucous membrane?  What is the difference in form between mucous
and serous membranes?  What are the results of inflammation in both membranes? De-
scribe the gums.
 
36
ANATOMY OF  A TOOTH.
Fig. 46.
cous membrane.  In the gums the teeth are fitted, their func-
tion being to masticate the food.
  The parts composing a tooth are the crown,
a, which projects above the gums, c;  the roots
or fangs, b, which are fitted in the maxillary
bones.  The crown is covered by a dense, hard
material, called enamel, e; while the bulk of
the  tooth consists  of substantia ostoidea, or
bone ivory,/.   The cavity in the interior of the
tooth is represented at d.
  The substantia ostoidea closely resembles bone in its consti-
tution, as is shown in the following  table.  The hardness of
Parts composing Teeth.
Enamel.	Substantia Ostoidea.
	
	
the enamel is also demonstrated to be due to the large amount
of inorganic matter it contains.  The cavity in the body of the
tooth is filled with a fatty pulp, in which the blood-vessels and
nerves subdivide before they enter the substantia  ostoidea.
From the great hardness and density of  the enamel of  the
teeth, we  should hardly expect  to find that  tissue  supplied
with so delicate a constituent as a nerve, but  the presence of
nerves in  the  enamel is demonstrated by  the pain produced
when a small hard substance, as a grain of sand, is entrapped
between the teeth while masticating.   The nerves gain access
to the pulp through a canal in each fang; whenever, therefore
there is any inflammation either of the fang or  of the crown
the substantia ostoidea is swollen, and, pressing upon the nerve
produces  toothache,  that most  annoying of  maladies.   It must
not be supposed, from the above  statement, that toothache is
always due to inflammation of the tooth, as it is more frequent-
ly a slight inflammation of the nerve itself,  a true neuralgia of
the nerves supplying the tooth.  Toothache is sometimes very
singular in its vagaries;  for example, the disease may exist in
a tooth in the upper jaw, and the patient will refer the pain to
one in the lower jaw, and not be satisfied that he is mistaken
until the  wrong tooth is extracted, without obtaining relief
from pain.
  The mineral  substances of which the teeth are composed  are
phosphate and  silicate of lime  and fluoride of  calcium.  They
 What are the parts composing a tooth ?  What is the proportion of animal and mineral
material in the enamel and sub ostoidea? What is the pulp  of the tooth composed of?
What are the causes of toothache ?  What are the mineral substances composing the teeth ? 
CLASSIFICATION OF TEETH.
37
are constituents of the  exterior covering  of wheat and other
cereals ;  consequent!)', in the finest varieties of flour, when the
covering has been  carefully separated, there is not a sufficient
quantity of mineral substances to nourish the teeth properly,
and we find the results in the defective teeth of the  children
of the wealthy, while those of the poorer  class, who live  on a
coarser flour, have sound and perfect teeth.
   A very common  cause of bad teeth is the use of preparations
of mercury in childhood.   Such preparations seem to stimulate
the growth of the  teeth, and cause their projection above the
gums before  they  have been properly covered  with  enamel,
which is  the  natural protection  of the  substantia  ostoidea
against the action of the juices of the mouth.
   There are two sets of teeth; the first is called the temporary
or milk set, numbering twenty, which are  loosely fixed in the
jaw, and are shed at the  sixth or seventh year; their roots be-
ing absorbed, and  the teeth then pressed  out  of their sockets
by the  second or permanent set, which begin  to appear when
the jaw-bones commence  to assume their final'form.
   The permanent teeth are thirty-two in number, each half jaw
containing two incisors or front teeth, one canine, two bicus-
pids, and three molars.   The incisors have a single fang;  they
Fig. 47.           Fig. 48.                   Fig. 49.
Incisor Teeth.        Canine Teeth.       Bicuspid Teeth.          Molar Teeth.
bite off the  morsel of food.   The canines also  have a single
fang, and are developed to a wonderful degree in animals that
live entirely on flesh, and are  regarded as an indication of the
habits of the creature to which they belong—all animals that
have canine teeth being carnivorous,  or flesh  feeders, while
those that do not possess them are herbivorous, or vegetable
feeders.
  The bicuspids have two roots and a flat crown;  they crush
 From what«sources are they derived ? Describe some of the causes that produce defect-
ive teeth.  What is the number of milk teeth ? Why are they so called ? How many per-
manent teeth are there ?  When do they  appear ? Into what classes are they divided ?
How many of each class in each half jaw?  What do the canine teeth mark? How many
roots have the incisors—canines—bicuspids ? 
38        ADAPTATION OF THE  TEETH TO THE FOOD.
Fig. 50.
the morsels that have  been separated by the  incisors.  The
molars have three roots and a large  flat crown; they  commi-
nute the food as perfectly as possible, and put it in the  most
favorable condition for the action of the various digestive
juices; they are  developed to  the greatest extent  in herbivo-
rous animals, enabling them to  crush  and subdivide the grain,
twigs, or grass on  which they feed.   Animals  that have the
molars well developed do  not possess  canine  teeth;  and in
those in  which the  canines are well developed, the molars are
changed  in character—become  cutting instead of crushing in
                           their action, and are called carniv-
                           orous  teeth.  From  the examina-
                           tion of the teeth of man  we find
                           that the  diet to  which they are
                           adapted is that which  the  experi-
                           ence of centuries  has taught us is
                           the best, viz., a proper  mixture of
                           animal and  vegetable  substances,
                           his herbivorous wants being shown
                           by his molar, and his carnivorous
                           appetite by his canine teeth.
  In some animals the teeth grow with great  rapidity, and are
                          only kept  of a proper size by being
                          continually worn away by  friction
                          against  the opposing teeth,  as  is
                          demonstrated  in Fig. 51, in which
                          one  incisor tooth of the upper jaw
                          having been broken, that of the low-
                          er jaw which opposed it has grown
                          to such an extent as to  form a per-
                          fect circle, and finally caused death
                          by interfering with  the power  of
                          mastication, the jaws being locked
                          together.
                            The  order in which the teeth ap-
                          pear is  as  follows: incisors in the
                          seventh and eighth year, canines in
                          the  eleventh, bicuspids in the ninth
                          and tenth, and molars in the seventh,
                          thirteenth, twentieth to thirtieth.
  The sides of the  mouth are formed by the  cheeks;' they  are
Human Lower Jaw.
Fig. 51.
Jaw of Rat.
 How many roots have the molars ? What inference may be drawn from the human teeth
as regards diet?  At what periods do the permanent teeth appear? 
                  THE STOMACH DESCRIBED.                39

composed of the buccinator muscles, which are covered on the
exterior by skin, and lined  on the interior by mucous mem-
brane.
   The roof of the mouth is called the  palate; the anterior por-
tion consists of bone  (palatal process of superior maxillary),
covered by mucous membrane; the posterior portion is com-
posed of muscles, covered by mucous membrane.  The first is
< >ften called the hard, and the latter the soft palate.
   On the floor of the buccal cavity lies the tongue, being form-
ed of muscle covered  by mucous membrane ;  it is very freely
supplied with nerves,  and is the organ of taste.
   On the  sides of the back part of the cavity there  are two
small projecting teat-like organs called the tonsils ; their func-
tion is  not known; between them a  similar  process  extends
from the soft palate called the uvula.
   The second division of the digestive tract is  the pharynx; it
is a pyramidal-shaped  box composed of muscles, and lined with
mucous membrane; it receives  the mass of  masticated food
from the mouth, and forces it into the oesophagus.
   The gullet or oesophagus is a tube formed of muscular fibre,
and  lined with mucous  membrane; it extends from the phar-
ynx  to  the stomach,  passing  down the neck and thorax in
front of the vertebral column, and piercing the diaphragm in
its course.  The  fibres  of its muscular  coat  are  arranged in
such  a  manner that some pass  around the tube, and others
                                       along  its  length.   It
                                       forces the  bolus   of
                                       masticated food, by a
                                       species of vermicular
                                       movement, from  the
                                       pharynx into the stom-
                                       ach.
                                          In the adjoining sec-
                                    / tion of the stomach, a
                                       represents the oesoph-
                                       agus ;  b, the  greater
                                       extremity;    c,   the
                                       smaller curvature; d,
the greater curvature; e,the pyloric end;/,li,the duodenum;
</, the entrance  of the ducts of the liver and pancreas.
  Describe the tissues composing the cheeks. What tissues form the palate ?  Describe the
organs in the posterior part of  the buccal cavity.  Describe the pharynx.  What tissues
compose it? Describe the oesophagus.  What tissues compose it?  What is the course of
the oesophagus ?  How does it act ?  Describe the position of the stomach.
 
40
THE  THREE  COATS OF THE STOMACH.
Fig. 53.
  The stomach may be described as a pear-shaped organ, lying
in the upper part of the abdominal cavity, under the liver, and
in the median line of the body, with the large end on the
left side, and the lesser or pyloric end on the right;  when it is
empty it collapses,  and occupies a very small space;  but  when
it is distended either by food or gas, it can be made to hold
about one gallon.  The walls of the stomach are composed of
three distinct membranes or layers, an interior coat  of mucous
membrane, a middle or muscular, and an external or serous layer.
  The serous coat  of the stomach is a portion of the peritone-
um, or great serous membrane of the abdomen, which  covers
the interior walls of that cavity  and all the organs it contains,
enabling them to move readily over each other without friction
during respiration and digestion.  The other serous membranes
                 are found covering the brain, lungs, and heart.
                 The synovial sacs of the joints may also be re-
                 garded as belonging to this  class  of mem-
                 branes.
                   The muscular coat is composed  of involun-
                 tary fibre, formed into bands or bundles, some
                 of which run around the greater diameter of
                 the organ {Fig. 53,1), and others around the
                 lesser, 2.  Their duty is  to cause the stomach
                 to contract  on  its contents equally, or to im-
                 part  to them  a movement  of rotation, by
                 which they are mixed with certain  juices, and
                 digestion  assisted.
                   The mucous  coat has  a special function to
                 perform, viz., the secretion  of the gastric juice;
                 it therefore  differs from the other membranes
                 of the same class in being provided with  a
                     number of glove-shaped depressions or
                     follicles.  The  interior of the  follicles is
                     lined  with secreting  cells, which form the
                     gastric juice most actively when food is
                    introduced into the stomach.
                        The oesophagus enters the stomach at
                     its large end; and, since the  entrance is
                     on the left side, and  under the  heart, it is
The Muscular Bands of the
     Stomach.
Fig. 54.
Mucous Membrane of Stomach,
  magnified 70 diameters.
 What is its shape—size?  What tissues compose its walls? What is the peritoneum?
Where are the other serous membranes found ? What class of muscle cells compose the
muscular coat of the stomach?  What is the duty of the muscular layer?  What is the
function of the mucous coat?  What are the follicles of the stomach?  What is their func-
tion ?  Name the ends of the stomach.  At which end does the oesophagus enter ? 
DIVISIONS OF THE INTESTINES.              41
Fig. 55.
called the cardiac opening.  After  digestion
by  the gastric juice  is completed,  the fluid
formed escapes into the intestine through an
opening at the opposite end, called the pyloric
opening, which is closed by the pyloric valve.
To  this valve great importance was attached
by  the ancients, who even believed it to be
the seat of the soul.
  The coats of the stomach, and especially the
mucous coat, are very freely supplied with
blood-vessels, which  are  intensely congested
during digestion.   The  supply of nervous
force is also very large; one nerve in particu-
lar, the pneumogastric, which is derived di-
rectly from the brain, and passes through the
thoracic cavity, giving branches to the lungs sections of stomach Fomcies,
on its way, seems to have control of the move-  masnlfied 15°Diameters-
ments of  the organ, and also to influence the secretion of the
digestive  juice;  for when it is cut or injured, the movements
of the stomach cease, the gastric juice is secreted at  a slower
rate, and  digestion is performed very imperfectly or not at all.
                      LECTURE  VIII.
              organs of nutrition—Continued.
Divisions of the small Intestine.— Coats  of the Intestine.—Movements of
  the Intestine.— Valvules Conniventes.— Villi, their Composition.—Divi-
  sions of the large Intestine.—Appendix Vermiformis.

  From the  stomach the food passes into the  small intestines,
which are described as consisting of three divisions, viz., duode-
num, jejunum, and ileum.
  All the divisions of the small as well as of the large intestine
are composed of three coats, like those of the  stomach, viz., se-
rous or peritoneal, muscular, and mucous.  The external  and
middle are the  same throughout the intestinal canal, the mid-
dle or muscular consisting of two sets of involuntary fibres, one
of which passes around the tube, while the other runs along its
length.  When the muscular bands  contract, a vermicular or
worm-like  motion is produced, which propels  the  contents of
  What is the pyloric valve ?  Name the nerve of the stomach.  Where does it take its or-
igin?  What is its function?  What are the divisions of the small intestine?  Name the
coats of the intestine.  What is the function of the  muscular coat ? 
42
THE  SMALL INTESTINE.
Fig. 56.
The Duodenum.
the  tube downward.   In perfect health, the motions  of the
stomach go on without our knowledge; but  when the  food is
not  properly digested, the contractions become  more violent,
and severe  colic is produce/!.   Sometimes the movements of
the muscular bands are inverted, and the contents of the stom-
ach  and intestines forced upward, as in vomiting.
   The internal mucous coat differs in the different parts of the
canal, and may with advantage be considered with the descrip-
tion of each division.
                                      The duodenum is  elev-
                                    en inches, or twelve fin-
                                    ger-breadths in length; it
                                    is  shaped like a  horse-
                                    shoe, so that its end lies
                                    under and a little behind
                                    its commencement.  The
                                    mucous  coat is velvety in
                                    character, the upper part
                                    for  an  inch or  so from
                                    the pylorus being smooth
                                    or thrown into vertical
                                    folds. When these exist,
they disappear in the second inch, longitudinal folds taking their
place, which are called valvulas  conniventes, and their function
seems to be to provide  the necessary amount of membrane to
enable the canal to be distended; it is also supposed that they
may be of use  in retarding the  passage of the food down the
intestine, and, by giving to it a movement of rotation, assist in
completing digestion.
   On the valvulas conniventes  there are minute projections,
which may be seen by allowing a stream of water to run for a
short time on a portion  of the intestinal mucous membrane, to
wash the mucus off, and then placing it in a  saucer under wa-
ter, when the villi arc visible, giving to the membrane  an ap-
pearance similar to that of cut  velvet.  These minute projec-
tions are found in the lower part of the duodenum and through-
out the intestinal canal, but chiefly in the middle region of the
small intestine.
   The second division is called the jejunum, because it is gen-
erally empty when examined.  It is about ten feet in length;
  Describe the duodenum.  What is the course of the folds in the first part of the duode-
num ?  Describe the valvulas conniventes.  What is their function ?  What gives the mu-
cous membrane its velvety appearance ?  Where are the villi chiefly found ?  Describe the
jejunum. What is its length ? 
THE  SMALL INTESTINE.
43
in it the valvulas conniventes are very prominent, and the villi
numerous.
  The third division, or ileum, receives its name on account of
the intricate twists into which it is thrown;
it also is freely supplied with valvulas and
villi, but they become less and less marked
toward its lower  extremity.  The length
of the ileum is about fifteen feet.
   In the figure the villi are represented at
a ;  the glands of Lieberkuhn, b; muscular
coat, c; follicles  of Peyer, d; submucous
tissue, e;  circular muscular bands,/; lon-
gitudinal bands, g, h.
  The total length of the  small intestine
is about twenty-six feet, and its diameter
one inch.   By some the duodenum is re-
garded as  a  species  of second  stomach,
but, from the above  statements, we find
that there is no proper foundation for the
opinion.
   From the  ileum the  undigested  food
passes into  the large intestine,  the length
of which is  about six feet; adding this to
the length  of the small intestine, stomach, and oesophagus, we
find that the  total length of the digestive canal in a person six
feet in height is thirty-four feet, or  nearly six times the height
of the I >ody.  The diameter of the large intestine is about three
inches, and it is  divided into six divisions, viz., cascum, ascend-
ing, transverse, descending colon, sigmoid flexure, and rectum
(see Fig. 44).
   The cascum is the commencement of the large intestine; it is
on the right  side of the abdominal cavity, and is  separated
from the ileum 1 >y a valve called the ileo-cascal valve, which re-
tards the passage of the portions of food that have not been
properly digested in  the  small intestine.   The cascum is de-
scribed as being pouch-like in form;  it is attached by its exte-
rior portion to the  wall of the abdominal cavity, in the right
iliac region, so that when the lower parts of the large intestine
are closed by disease, and  the fasces  can not pass, a fistula  or
artificial communication may be made with the intestine  in
  Describe the ileum.  How long is it ?  What is the length of the large intestine ?  What
is its diameter ?  What is the total length of the digestive apparatus ?  What are the divis-
ions of the large  intestine? Describe the caecum.  What is its position ? What valve sep-
arates it from the small intestine ?
Section of Wall of Ileum magni-
    fied 50 Diameters. 
44
THE LARGE INTESTINE.
this  region, and  the life of the patient prolonged.  This  is
sometimes done, though existence must be almost unendurable
when we consider the discomforts  and annoyances which at-
tend the necessity of an artificial anus, as it is called.
  To the anterior surface of the cascum, a small worm-like tube,
the appendix  vermiformis, is attached; it is not of any use in
man, though it is developed to an enormous extent in some an-
imals and birds, becoming one of the important divisions of the
digestive canal, and  reaching in the ostrich a length of nearly
three feet.
  Though the appendix is merely rudimentary in man, and has
no special duty, it is by no means to be overlooked or disre-
garded, for it often happens that an undigested hard substance,
like  a cherry-stone,  is by some  accident caught in the mouth
of the appendix, and originates an inflammation similar to  that
produced by  a splinter  in the skin; this may continue for
months, and I know of one instance in which a  cherry-stone
was  impacted in  the appendix, and remained there for many
years, producing epileptic convulsions, and finally caused death
by perforating the intestine, and passing into the cavity of the
peritoneum, where it was found on  making  a post-mortem.
  The second division of the large intestine  is the ascending
colon; it passes up  on the right  side, and terminates in the
transverse colon, or third division, which crosses from the right
to the left side, lying immediately  under the stomach; reach-
ing the left side, the  colon curves downward to form the fourth
division, or  descending colon, which, in the left iliac fossa, be-
comes  an S shaped  curve called the  sigmoid flexure,  or  fifth
division.  The end  of this flexure, or bend of the large intes-
tine, lies in the upper part of the pelvic cavity, opposite the su-
perior surface of the  sacrum; from this point the intestine
passes downward, following the concavity of the  sacrum, and
forming the sixth division or rectum, which is closed below by
a band of voluntary  muscular fibre that forms  the  anus or
opening.
  The coats of the large  intestine are the same as  those of the
jejunum, but  less freely supplied with villi.   Certain glands
are also found in this part of the digestive mucous membrane,
which will be hereafter described.
  What is an artificial anus ?  What is the appendix vermiformis ? What is its function ?
Under what circumstances is the appendix dangerous? Where  is the ascending colon?
Where is the transverse colon ?  Where is the descending colon ?  Where and what is the
sigmoid flexure ?  What are the coats of the large intestine ? 
THE  BUCCAL  GLANDS.
45
                       LECTURE  IX.
  /            organs of nutrition—Continued.

                         THE GLANDS.
Buccal Glands.—Description-of the Scdivas.—Properties of mixed Saliva.
  —Nature of Ferments.—Abdominal Glands.—Duty of the Liver.—Na-
  ture and Properties of Bile.— The Pancreas.—Nature and Properties of
  its Secretion.— Oriyin and Properties of Gastric Juice.— Uses of Pep-
  sin.— Origin and Properties of Intestinal Juices.
  After the food has been properly subdivided, it  is mixed
with certain juices which are secreted by glands.   The glands
are arranged under the following heads: 1st. Those of the buc-
cal cavity;  2d. Those of the  abdominal cavity.
  The glands of the buccal cavity are
the  parotid, submaxillary, and sublin-
gual ; they are also called the salivary
glands.   The  parotid gland, p, is  be-
neath the ear, and behind the lower jaw
on each  side;  its secretion is conveyed
to the mouth by means of Steno's duct,
s, which crosses the  buccinator muscle,
and pierces it near the centre, deliver-
ing the saliva into the  mouth opposite
the second molar tooth, so that it is min-
gled with the food while  it is being
masticated  by the  teeth;   it  is well
adapted to the purpose of forming a pasty mass with the food,
for it contains more water than any other saliva.
  The submaxillary glands  are behind the horizontal part of
the  inferior maxillary bone; their secretion is more consistent
than that of the parotid gland, and is conveyed to the mouth
by Wharton's duct, which  opens  close  to  the bridle of  the
tongue.   The  sublingual glands are under the tongue  on each
side  of the  bridle;  their  secretion  is delivered by fifteen  or
twenty ducts,  which  perforate tms  mucous membrane of  the
  Into what classes are the glands divided?  Name the glands of the buccal cavity.  De-
scribe the position of the parotid gland.  What is the name of its duct ? What is its course ?
What is the function of parotid saliva?  Where is the submaxillary gland?  What is the
name of its duct ? Where does it enter the mouth ?  Describe the sublingual glands.
Parotid Gland. 
46
PROPERTIES  OF SALIVA.
floor of the mouth.  The function of submaxillary and sublin-
gual saliva is to coat the food with a slimy material, which fa-
cilitates its passage into the stomach.
  The secretion  of the  glands  of the  buccal cavity, together
with that of the  mucous membrane, is called mixed  saliva; it
is  alkaline in its reaction, turning red litmus blue.   The  con-
stituent which produces this result is free lime, as is shown by
the pellicle of carbonate of lime which forms on the surface of
saliva  that is  allowed to stand  in  the  open  air.  The total
amount of saliva secreted in twenty-four hours  is  fifteen or
twenty ounces, but it depends to  a great  extent on the  excite-
ment to which the glands  are subjected.  During the mastica-
tion of food, or in speaking, the secretion is greatly increased;
mental impressions produce a similar result, as the expectation
of a good meal, or the odors given  off during the cooking of
various savory dishes.
   One of the most important ingredients of saliva is a nitro-
genized body called ptyaline; it belongs to  the  class  of fer-
ments which possess the power of causing other substances to
undergo change  with more  or less  rapidity.   Each of  the di-
gestive juices contains a ferment,  and they seem to be essential
to the proper performance of digestion.   They are  all bodies
which may be said to be in the act of undergoing final  decom-
position ;  and it is one of the most beautiful illustrations in the
whole domain of physiology  of the manner in which materials
are  consumed, that the dying, effete  nitrogenized  substances
which are no longer of any use in the system should, in being
cast out, aid in  the introduction of new nutritive  materials,
teaching us the lesson that in the laboratory of nature nothing
is lost, nothing is wasted.
   The slimy nature of the submaxillary  and sublingual juices
also causes a considerable amount of air to be entrapped  with
the food and carried into  the stomach, where it assists  the di-
gestive juices in  dissolving the food.
   The abdominal glands connected  with  digestion are the liv-
er, pancreas, stomach follicles, and intestinal glands.
   The liver is the largest gland  in the body, its weight being
four pounds;  it lies immediately under the stomach,  and  is
held in position by ligaments formed of folds of peritoneum.
  What is the function of submaxillary and sublingual saliva ? What is the reaction  of
mixed saliva ?  What substance gives it  this reaction ? How much saliva is secreted in
twenty-four hours?  What causes influence the production of saliva? What is the ferment
of saliva? What is the composition and  nature of ferments?  What special function does
submaxillary saliva perform ?  Name the abdominal glands.   What is the weight of the liv-
er? Describe its position. 
                   THE  FUNCTIONS OF BILE.                 47

It is divided into two farge lobes, the right being the largest;
in addition to these, anatomists mark out two or three smaller
lobes.   It is freely supplied with blood by arteries, and also
receives through a short trunk, called the portal vein, the blood
from all the other organs in the  abdomen except the kidneys.
The gall-bladder is attached to the  under surface of the liver,
and serves  as a reservoir in which the
excess of bile is  retained  until it is  re-
quired for use.
   In the adjoining figure  the right and
left lobes are represented, together with
the blood-vessels  of the organ and the
gall-bladder.
   The  liver  separates  bile from the
blood, and  empties it, by means  of the
hepatic duct, into the intestine.  If we  examine the blood be-
fore it enters the organ  and as it passes  out, we find  that sugar
has been formed, and a certain quantity  of fat has disappeared,
showing that another very important duty of the liver is the
transformation of fat into sugar, and that it is  intimately con-
nected  with the function of respiration.  It also produces a pe-
culiar fat called cholesterine, which is employed as an external
covering of nervous fibres.
   Bile  is a yellow or green  fluid, with an alkaline reaction, due
to the presence of free soda.  It is not formed in the liver, but
in the blood, the liver merely filtering  it  out from  that fluid.
The total amount secreted in the course of a day is fifty-four
ounces.  It is the natural stimulant of the intestines, as is shown
by the  fact that wdien it  is  deficient in  quantity the intestines
act in a sluggish manner, and only  resume  their energy again
when the secretion of bile is increased  either naturally or by
the use of medicines.
   It has been supposed by some physiologists that bile was an
important agent in the  digestion of the food, but this opinion
is in a great degree controverted by  the fact that the secretion
of this juice is most rapid about  thirteen hours after the chief
meal of the day, and at the time when  the intestinal action is
most energetic in the endeavor to remove the undigested mate-
rials to the lower part of the digestive canal.

  From what sources does it receive blood ?  Where is the gall-bladder ? What is its func-
tion? What is the duty of the liver?  What change is impressed on the blood during its
passage through the liver?  What is cholesterine?   What is its function?  Describe bile
and its properties.  Where is it formed ?  What is the diurnal amount of bile? What is its
function ?  A* what time is bile secreted in largest quantity ? 
48
PANCREATIC DIGESTION.
The Pancreas.
           FigG0-               The pancreas is represented at
                            o in the adjoining figure, g being
                            the gall-bladder; s,the cystic duct;
                            c, the ductus  communis  choledo-
                            chus; J9,the pyloric valve; e e, the
                            duodenum; i, the termination of
                            the duodenum.
                              The pancreas resembles the sal-
                            ivary  glands  in its ^structure;  it
                            varies  in size, weighing from  two
                            to five ounces.  It lies in the curve
                            of the duodenum, across  the  ver-
                            tebral column.-   The duct com-
mences at the  small end, and, passing out at the head of the
gland, unites with the ductus communis before it pierces the
intestine.
  The common duct of the liver and pancreas is about the di-
ameter of a goose-quill; it enters the duodenum near the  cen-
tre  of the middle portion, passing  through the coats in an ob-
lique manner, forming a valve.
  The diurnal secretion of the pancreatic  fluid is about thirty
ounces; it is alkaline in its reaction, owing to the presence of
soda;  ifs  ferment is called pancreatine.   The special  function
of pancreatic fluid is to digest fatty bodies, as is  demonstrated
by the fact that when the pancreas is diseased, these substances
are not digested, but pass out in the fasces.
  The stomach follicles have been described in  the  discussion
of the mucous membrane of the stomach.  They secrete a fluid
called the gastric juice;  it has a strong  acid reaction, owing to
the presence of hydrochloric acid, which is fprmed by the de-
composition of common salt in the presence of water,  as is ex-
pressed by the adjoining symbols, which also demonstrate  that
soda is at the same time produced, and, as we have seen, makes
its appearance in the bile and pancreatic fluid.
Common Salt
Water
NaO, Soda.
  The ferment of the gastric juice is called pepsin;  it may be
collected in quantities from the stomach of the calf for the pur-

 Describe the pancreas ; its weight; position.  What is the course of its duct ?  What is
the diurnal amount of pancreatic fluid? What is its special function?  What is the reac-
tion of gastric juice ?  To what substance is its reaction due ?  Explain the origin and form-
ation of the acid.  What is the ferment of gastric juice ? 
INTESTINAL GLANDS.
49
poses of experiment; its function, as we shall fully demonstrate
hereafter, is to aid the acid  in  dissolving  certain articles of
food.
  The intestinal juice is secreted by a number of glands, class-
ified as, 1st. Brunner's, which are about the  size of hemp-seeds,
and scattered throughout the intestines, but are chiefly found
in the mucous membrane of the  upper part of the small intes-
tine ; 2d. The follicles of Lieberkuhn, which resemble the Stom-
as- 61-                 Fig. G2.                 Fig. 63.
Brunner's Glands.          Follicles of Lieberkuhn.          Peyer's Plates.
ach follicles;  they are also found in all parts.of the intestinal
mucous membrane; 3d. Peyer's plates, which are circular glands
without ducts, and found in the lower part of the small intes-
tine and the colon.
  The intestinal juice is  acid in its reaction, and contains a fer-
ment similar to pepsin;  it acts  upon the same articles of food
as the gastric juice, dissolving  those portions which have es-
caped stomach digestion.
                        LECTURE  X.

                             FOOD.

Annual Amount of Food  consumed.—The Ingesta. — The Introduction
  and Use of Water in the System.—Latent Heat of Vapor of Water.—
  Variatio?i in the Food of different Nations.

  Having completed the study of the various parts of the di-
gestive apparatus, we are prepared to examine into the duties
of each portion ; for, as the characters of the juices in the dif-

  What is the function of pepsin ? What is the source of the intestinal juice ? Describe
Brunner's glands.  What are Lieberkuhu's follicles ?  What are Peyer's plates ?  What are
the properties of intestinal juice ?
                              D 
50          NATURE AND PROPERTIES OF INGESTA.

ferent divisions  of the digestive  canal differ, so also  do they
differ in their action, some articles being digested by one juice
and not by others.
  That man is a destructive machine is abundantly proved by
the fact that in the course  of a year he takes into his system
more than three thousand pounds of materials; and, since the
weight of an adult does not increase, a  similar amount must
also be voided.  The materials  introduced are called the in-
gesta, those voided are called egesta.
  The ingesta may be classified under the following divisions,
the amount  of each class having been obtained from the army
and navy ration-scales of different nations, and by experiment:
                         Annual Ingesta.
         Water............................................................. 1500 lbs.
         Food...............................................................  800 "
         Air................................................................. _800 "
                                             3100 "
The egesta also  amount to 3100 pounds, and consist of expired
air, perspiration, urine, and  fasces.
  Water may be introduced into the system by immersing the
body in  a warm bath, after which it will be found to have in-
creased in wreigh.t, the amount of increase depending upon the
previous abstinence from the use of liquid.  It is stated that
shipwrecked sailors, whose bodies  are  exposed to continued
contact with water, do not  suffer thirst,  the liquid being intro-
duced through the vessels of the skin.
  The uses  of water in the system are, 1st. To form the food
into a solution, so that it  can be taken up by the vessels which
are intended to absorb the fluids produced by digestion;  2d.
To form the basis of all the circulating juices of the body;  3d.
To keep down the temperature  of the body to 98°;  and, 4th.
To carry effete or oxidized  substances out of the system in so-
lution.
  In  order to  appreciate how powerful an agent water is in
controlling the temperature of the body, we have only to exam-
ine into the change it undergoes in being converted into vapor
or steam.  If we take a given quantity of water and subject it
to the action of heat in such a manner that the temperature of
the mass shall rise one  degree per minute, we find that it will
follow the law until it  reaches 212°, when  the  temperature no

  What is the annual amount of ftigesta ?  What are the  egesta ?  What are the divisions
of the ingesta ?  What is the amount of each ?  What  are  the divisions of the egesta ?
How may water be introduced into the system?  What are the functions of water in the
system ?  How does water control the temperature of the body ? 
FUNCTION OF WATER  LN THE SYSTEM.
51
longer rises, but remains at that point until the liquid has all
evaporated as steam, which requires 1000 minutes.   If we place
a thermometer in the steam as it rises from the water, we find
that its temperature is the same as that of the liquid, although
it has  absorbed all the heat that was passing into it for 1000
minutes.  From this and other experiments, we find that steam
differs from water in containing 1000  degrees  of heat in a la-
tent or hidden form that is not appreciated by the thermome-
ter ; consequently, the total amount of heat in boiling water be-
ing 212°, that contained in the steam rising from it is 1212°.
  Applying the above facts to the explanation of the results
produced by the evaporation of water from the skin and lungs
we find that the  vapor of water, which is continually rising
from the surface, conveys away the excess of heat that has been
generated during  the performance of the various functions of
the different parts of the body.
  Water, food, and air constitute the ingesta of all men in all
parts of the world.   Of these, water and air  present but very
slight modifications or variations; they may therefore be regard-
ed as invariable  in their  character.  But this is not the  case
with food.   The Esquimaux or Laplander will devour an enor-
mous amount of oil or whale blubber, and would at any time
prefer  a lump of tallow to the  most daintily-served entree,
while the West Indian can hardly be  induced to eat any fat
substance, but delights in fruits with which nature generously
supplies him in great variety.
                       LECTURE XL

                     DIVISIONS OF FOOD.

Milk, its Composition and Variations.—The nitrogenized Group.—The
  non-nitrogenized Group.—Hydro-carbons.— Carbo-hydrates.—Fermenta-
  tion of Starch and Sugar.—Influence of Temperature on Fermentation.
  — Composition of Flour. — Bread-making. — Wine-making. — Use of
  Phosphate of Lime.— Of Chloride of Sodium.

  Though the diet of adults may be  variable, such is not the
case with the newly-born infant, for milk presents a uniform
constitution as regards the nature of its ingredients, though
their proportions may vary.

 What is meant by latent heat?  What is the latent heat of steam rising from "boiling wa-
ter ?  How does the evaporation of water influence the  temperature of the body ? 
52
THE  NITROGENIZED  GROUP.
                        Composition of Milk.
                        ......... 873
                        ......... 48, Nitrogenized and nutritive.
                        ........ jLl Respiratory and non-nitrogenized.
                        ........  2.30) c ,.
                        .........  2.70} Salts"
                            1000.00
  The milk of the human female varies but little in its compo-
sition, though it is said that the milk of the brunette is richer
than that of a blonde.  The animal milk that approaches more
nearly in character to human milk than any other is that of
the ass; it therefore follows that it is better  adapted to the
nourishment of the human infant than any other form of diet
except the natural supply.   Owing to the difficulty of obtain-
ing asses' milk, cows' milk is generally substituted; but it is so
much stronger than human milk, that it must be diluted with
three or four times its volume of water, and  sufficient sugar
added to make it sweet to the taste; it then forms  an excel-
lent substitute.   But if it is not properly diluted, it often disa-
grees with the child, giving it  diarrhoea, and finally causing
death.  I have  frequently been surprised at the want of in-
formation that exists  among mothers, and even among physi-
cians, regarding the above simple facts; and have aided in pro-
ducing the recovery of infants that have been wasted away to
mere  skeletons, by simply directing attention to their diet, and
causing the milk which  had been given in the  undiluted state
to be properly reduced with water, in order to adapt it to the
digestive powrers of the child.
  The second component in  order of quantity  is casein, which
furnishes the curd when the fluid turns sour, and is the mate-
rial that forms  cheese.   It is composed  of the  chemical ele-
ments, carbon, hydrogen, oxygen, and nitrogen / it is therefore
called a nitrogenized  substance, and is one member of an im-
portant division of food, the others being, 1st. Fibrin,  which
possesses the power of self-coagulation; it is formed in the
blood, and is employed in nourishing muscular  tissue, of which
it is the chief constituent; 2d. Albumen, also found in blood
but existing in a purer state  in the white of eggs; it does not
coagulate spontaneously, but can be made to assume the solid
form  either by heating  to 180° F., or by adding certain acids
or other chemical agents; 3d. Gluten, or vegetable fibrin, may
 What are the ingredients of milk? Does human milk vary in its composition?  What
variety of milk resembles human milk ?  Is cows' milk suitable for infants ?  What is case-
in ?  To what group of food does it belong ? What are the other members of the nitrogen-
ized group ? What are their properties ?
Water..............
Casein..............
Sugar...............
Butter...............
Phosphate of lime,
Salt.................. 
             DIGESTION OF  NITROGENIZED  SUBSTANCES.         53

  be  obtained  from  any plant,  or from  the flour  of various
  seeds.
    Professor Playfair says, " Vegetables are the true makers of
  flesh; animals only arrange  the flesh which they find  ready
  formed in animals and plants.   If we go farther down in the
  chain, we find all food in the debris  of rocks, for the breaking
  up  of these form  the earth, from which it is eliminated by the
  chemistry of plants, to be farther sorted for man's use in the
  bodies  of animals.  We thus see how significant and literally
  true is the term we apply to the earth of' our great mother.'"
    The  nitrogenized bodies, albumen, fibrin, casein, and gluten,
  are also  called nutritive and  histogenetic (tissue  building),
  since they are employed in nourishing all the tissues  of the sys-
  tem to  a greater or less degree.   They may be dissolved with-
  out difficulty, and formed into a fluid solution by dividing
  them into small pieces, and keeping them for several hours in
  dilute hydrochloric acid, the temperature of which is  maintain-
  ed  steadily at 150° to 200°.
    If to the mixture of acid and nitrogenized substances a little
  pepsin  is added, the action then goes on at a temperature of
  100°  as rapidly as at 200° without the pepsin; from which we
  conclude that the ferment impresses some change on nitrogen-
  ized substances, which  enables  the  acid  to dissolve them at a
  temperature as low as that of the stomach, viz., 102° to 104°.
    Butter and sugar form a very considerable portion of the
  solid constituents of milk.  They are composed of hydrogen,
  carbon,  and oxygen, and do not contain nitrogen; they are
  therefore described as non-nitrogenized bodies.  They are em-
  ployed in the system as combustibles, by the burning of which
  the animal heat can be maintained;  consequently they are oft-
  en  spoken of as calorifacient or respiratory food.
    The non nitrogenized bodies are subdivided into two classes,
  owing to the difference in the quantity of the elements they
4 contain;  and  since the  subdivision has a practical value in the
  study of the  digestion of respiratory substances, we shall de-
  vote a few lines to its consideration.
    Butter, fat,  and all oily bodies contain an enormous amount
  of  carbon, hydrogen,  and but  very  little  oxygen;  they are
  therefore called hydro-carbons, and constitute the first subdi-
  vision.   The  amount of oxygen they contain being  so  small,
    What other names are given to the nitrogenized group ?  How may nitrogenized sub-
  stances  be dissolved ?  At what temperature ? How does pepsin influence the action ?
  What substances form the non-nitrogenized group?  What other names are given to this
  group ?  What are its subdivisions ? What are the peculiarities of the hydro-carbons ? 
54
NATURE OF  FERMENTATION.
they can in  a  given weight furnish a far greater  amount of
heat during their combustion in the body than can be obtained
from the same weight of sugar.
  Sugar, starch, gum, and similar substances contain hydrogen
and oxygen in  equal proportions, so that the hydrogen may be
regarded as  useless, since it  is  already united with as much
oxygen as  it has affinity for, and the  carbon only is available
for  the production of heat.   The proportion  of carbon in this
group  is also very  small, the number  of atoms being  about
equal to the number of atoms of hydrogen.  Owing to the pro-
portions in which the constituents  exist, it has received the
name of the carbo-hydrate division.
  If sugar is mixed with saliva, and kept at a temperature of
100°, it undergoes a change, the sugar gradually  disappearing,
and lactic  acid taking its place.  Starch  also  undergoes  a
change when brought  in contact with  saliva, first being  con-
verted into glucose, a  species of sugar, and finally into lactic
acid.   These changes  are due to the action of the ptyaline of
the saliva, and belong to the class of phenomena included un-
der the head of fermentation, the study of which is necessary
in order to understand the digestion of the carbo-hydrates.
  Fermentation is not only of interest  in connection with the
mere act of digestion of  starch  and sugar, but, since it lies at
the basis of such operations as bread-making and wine-making,
it becomes doubly interesting to the student.
  In order, to produce the fermentation of sugar,  a  solution of
the substance should be mingled with some suitable decaying
nitrogenized ferment.  Nothing  answers the purpose better
than yeast.  Placing such a mixture in  a cool place, where the
temperature does  not  rise above 70°, it  after a while takes on
an internal movement, attended by the evolution  of a consider-
able amount of gas.
  If the gas is  collected, and examined by suitable tests, it is
found  to be composed of carbonic acid; and if the liquid is
submitted  to distillation after the fermentation has ceased, it is
found  to contain a large quantity of alcohol.   This is the case
so long as  the temperature is kept below 70°; if it is allowed
to rise above that degree, and approach 90° or 100°, carbonic
acid and alcohol are no longer produced, but  lactic acid takes
  What substances form the carbo-hydrate group?  What are their peculiarities?  Which
group of respiratory food furnishes the greatest amount of heat? What is the action of sa-
liva on sugar—on starch?  What is the cause of the action ?  Upon what action do wine
and bread making depend? Describe the fermentation of sugar at  70°.  What  gas is
evolved at this temperature ? What is produced besides carbonic acid ?  What are the
products when sugar ferments above 70° ? 
       INFLUENCE OF TEMPERATURE ON FERMENTATION.     55

their place.   Temperature, therefore, has a controlling influence
over the fermentation of sugar, and decides whether it  shall
undergo the lactic or the alcoholic fermentation.
   From the  above facts, we see why it is that  the wine-maker
resorts to the use of underground cool vaults in carrying on
his business; he knows that if the temperature should  even
for a short time rise above a certain degree, the whole vat of
juice would be lost, and vinegar produced instead of wine.
   In the fermentation  of starch the effect of temperature is as
marked as in the case of sugar; but lactic acid is produced be-
low 70°, and alcohol and carbonic acid above 70°.
   Starch is contained in all varieties of flour, as may be readily
shown by taking a  small quantity and making it into dough
by the addition  of a little water.  If the mass of dough is then
kneaded under  the  surface of water, a fine powder is slowly
washed out, which sinks to the  bottom of the vessel, and a te-
nacious mass remains  in the hand, which is the gluten of the
flour.
   In the making of bread a certain degree of porosity is to be
obtained, which renders it  more digestible.   This is accom-
plished by forcing the  starch to undergo fermentation, the pro
cess consisting in taking  a given quantity of flour, mixing it
with water and  yeast, and  setting it aside in a  warm place un-
til fermentation  is thoroughly established.   More flour is then
added, the mass worked up, divided, and set aside for the fer-
mentation to continue for a short time; it is then placed in an
oven at a temperature of about 400°.  The high temperature
stops the fermentation, and is applied long enough to drive off
the excess of water and the alcohol that has  been produced.
The bread is then said to be baked.
   If the temperature of the dough is allowed to fall below 70°,
the lactic fermentation sets in, and the bread turns sour.   It is
then unfit for use, since mastication converts it into a paste, the
interior of which the digestive juices can not penetrate.
   In the Kensington Museum there is a case containing differ-
ent varieties of  bread, Avhich presents  some facts of  interest.
Among the  specimens exhibited there is a loaf of ordinary fer-
mented bread, two years old,  which is converted into a mass of
green fungus, while  the samples of unfermented bread of the
same age are perfectly  free from any such growth.
   In the same case there are specimens of New Zealand bread
 What are the products of fermentation of starch above and below 70° ? What is the com-
position of flour ?  Describe the chemistry of bread-making.  What is accomplished in bak-
ing bread ? Why must  the dough be keDt in a warm place ? 
56
GASTRIC DIGESTION.
made of the pollen of a reed;  also Dika bread, from Africa,
which has the appearance of Castile soap when cut.   There is
also a specimen, said to have been found in Lake Zurich, and
supposed to belong to  the stone period, but there are doubts
regarding its history.
  The salts are phosphate of lime and chloride of sodium, or
common salt.  The first is employed in  the nutrition of the
bones, and the second, as we have seen, is  essential to the prop-
er conduction of digestion, furnishing hydrochloric acid for the
gastric juice, and soda for the bile and pancreatic fluid.
                       LECTURE XII.
                          DIGESTION.
 Mastication.—Action of Saliva.—Action of Gastric Juice.—Formation
   and Properties of Chyme  and Chyle.—Action of Pancreatic Juice on
   Hydro-carbons and Carbo-hydrates.— Old and new Theories of Diges-
   tion.—Digestibility of various Articles of Food.—Effect of Quantity on
   the Rate of Digestion.—Indigestion as a Disease and a Symptom.—Ef-
  fect of Nature of Diet on Length of Intestine.—Digestive Apparatus in
   certain Animals.

   Having described the digestive apparatus, and  examined
 into the nature of the ingesta and digestive juices, Ave now pass
 to the detailed explanation of the processes to which the  food
 is subjected before it  is properly prepared for  absorption by
 the blood-vessels and lacteals.
   The first operation to which it is  submitted is  mastication,
 during which it is not only thoroughly subdivided, but also
. mixed with saliva and air.   It is  then swallowed, and, passing
 into the stomach, the ptyaline of the saliva commences immedi-
 ately at the existing temperature to convert starch into glucose
 or sugar, and then into lactic acid.  While  this is going on in
 the interior of the mass, the gastric juice is acting with energy
 on its exterior, the hydrochloric acid, by the aid of the pepsin,
 dissolving the nitrogenized  substances, albumen, fibrin,  casein,
 and gluten, converting them into soluble peptones.  Gradually,
 by the agency of the saliva and gastric juice, the  mass is broken
 up, and a fluid called chyme produced, which is of a tawny yel-
 low color, and contains the ©ils and fats undissolved.
  What is the use of phosphate of lime ?  For what purpose is chloride of sodium  employed
 in the system? What is accomplished by mastication?  What is the action of the gastric
 juice ? Where is its action carried on ?  What are peptones ?
« 
DUODENAL  DIGESTION.
57
   The saliva is indirectly very efficient in promoting true gas-
 tric digestion, that is, in dissolving substances of the nutritive
 group;  for the product of its action on starch and sugar is lac-
 tic acid, which attacks and dissolves nitrogenized bodies almost
 as readily as hydrochloric acid.   While, therefore, the acid of
 the gastric juice is acting on the exterior  of the mass in the
 stomach, the lactic acid, which is being continually produced in
 its interior, is also assisting  in the formation of a  solution.
   In persons who swallow  their food without proper mastica-
 tion, the saliva is not thoroughly mingled with it, consequently
 lactic acid is not formed in sufficient quantity; the whole duty
 of gastric  digestion is  thrown on the gastric juice;  it takes a
 longer time to accomplish the solution of the food, and the per-
 son suffers from an indigestion for which there is no cause but
 indolence, unless  the teeth  are so imperfect that mastication
 can not> be properly  performed.
   From the stomach the chyme oozes little by little through
 the pyloric valve into the duodenum, where it meets the pan-
 creatic fluid  and bile, and  quickly, under  their  influence, be-
 comes converted into a milky fluid, to which the name of chyle
 is given.
   Chylification consists in converting the oils  and fats into  an
 emulsion, so that they  can be dissolved or suspended in water.
 If soda is added to any fatty substance in sufficient quantity, it
 unites with it to form a soap, in which state it  is soluble in wa-
 ter ; but the pancreatic fluid contains albumen as well as soda,
 and each minute globule into which the oil or fat has been di-
 vided by the  soda is covered with an extremely thin layer or
 covering of albumen, forming an emulsion, in which condition
 the fat can be introduced into the absorptive  mechanism, and
 finally reach the blood.
   Pancreatic juice not only converts the fats  and oils into an
 emulsion, but  it also  acts on  starch and sugar with even great-
 er energy than saliva, its  pancreatine forcing them to undergo
 the  lactic  fermentation with great  rapidity.  Owing to this
 property of the pancreatic  fluid, nearly  all the  particles of
 starch  or sugar that  have escaped the  action of saliva are di-
 gested by  pancreatic juice,  and converted  into lactic  acid  in
 such quantity  that the alkaline reaction of the fluids of the
 duodenum is lost when the lower part of the small intestine is
  How does saliva assist the gastric juice ?  What is the effect,of bolting the food ?  Where
and by what juice is chyme converted into chyle ?  What is meant by chylification ?  What
is the difference between an emulsion and a soap? What is the action of pancreatic juice
on carbo-hydrates ? 
58        TRUE NATURE OF THE DIGESTIVE  PROCESS.

reached, an  acid  reaction  taking its  place,  and  continuing
throughout the large intestine.
  The juices of the intestinal glands are acid in their reaction.
The mixed juice contains a ferment, probably derived from the
follicles of Lieberkuhn; it  acts on nitrogenized bodies, dissolv-
ing them with ease, and completes the digestion  of those por-
tions  of nutritive food which have escaped the action of the
gastric juice in the stomach.
  The above account of digestion is now generally accepted as
the true  explanation  of .that  function.  Among the various
opinions that have been held regarding it, we may mention the
mechanical hypothesis which supposed that the food was dis-
solved by a species  of grinding operation by the walls of the
stomach.  This was finally overthrown in favor  of the chem-
ists by taking various articles and shutting them up in spher-
ical silver balls, the walls of which were perforated, to allow
the gastric juice free access to their contents.   On giving them
to dogs to swallow, and then withdrawing them from time to
time (by means of a string attached in a proper manner), and
examining their condition, it was found that the contents of
the spheres were slowly dissolved, showing that mechanical ac-
tion was not essential, though it might assist digestion.
  Every person  knows, by his  own experience and by the
statements of friends, that certain  articles of food are more
readily  digested than  others.  The comparative digestibility
of ordinary articles was determined by Dr. Beaumont, who had
a patient, Alexis St. Martin, in whose abdomen  there was an
opening that communicated with the  stomach, and  which was
the result of a gun-shot wound.
  Beaumont states that when the stomach  was empty, the mu-
cous membrane was of a pale color; but when food was intro-
duced, it immediately assumed a bright pink tint, owing to the
congestion of the blood-vessels, and in a few moments the
mouths of the  follicles were  marked by  small lucid points,
caused by the flow of gastric juice.
  The gastric juice exuded with  equal freedom both when the
food was introduced by the mouth or by  the opening in the
abdominal walls through which the observations were made.
  What is the reaction in the upper and lower parts of the intestine ? What is the reaction
of the intestinal juices ?  What do they accomplish ?  What was the old theory regarding
digestion ? How was the mechanical theory disproved, and the chemical established ?  How
was the digestibility of various substances determined? What is the color of the gastric mu-
cous membrane before and after the introduction of food? What is the appearance present-
ed by the mouths of the follicles ? 
RELATIVE DIGESTIBILITY OF VARIOUS ARTICLES.       59
   If the following table, furnished by Beaumont, is carefully
examined, it will be noticed that the method of cooking also in-
fluences the rate of digestion, fried articles being more indigest-
ible than those which are roasted or boiled.

  Table showing the Time required for the Digestion of various Articles.
                               h. m.i                              h. m.
Apples, sweet, raw............................ 1 30 Milk, boiled..................................... 2 00
      sour, mellow, raw................... 2 00  " raw....................................... 2 15
Beans, pod, boiled...........................'..  2 30
Beef, fresh, rare, roasted....................  3 00
  "    "  dry,    "   ....................  3 30
  "    "  fried..............................  4 00
Mutton, fresh, roast.......................... 3 15
   "     "  broiled........................ 3 00
   "     "  boiled......................... 3 00
Oysters, fresh, raw............................ 2 55
Beets,boiled................................... 3 45  "     "  roast.......................... 3 1
Bread, wheat, fresh baked.................. 3 30j  "     "  stew........................... 3 30
  "  corn,   "     " .................. 3 15:Parsnips, boiled............................... 2 30
Butter, melted................................. 3 30 Pork, fat and lean, roast..................... 5 15
Cabbage with vinegar, raw.................  2 00
       boiled................................  4 30
Catfish, fried...................................  3 30
              broiled.................. 3 15
              raw....................... 3 00
Potatoes, Irish, boiled........................ 3 30
Cheese, old, strong, raw..................... 3 30|   "    "  baked........................ 2 30
Codfish, cured dry, boiled................... 2 00 Rice, boiled..................................... 1 00
Corn, green, and beans, boiled.............  3 45
Custard, baked.................................  2 45
Ducks, domestic, roasted....................  4 00
  "   wild, roasted.........................  4 30
Eggs, fresh, hard boiled.....................  3 30
  "    "  soft   "  .....................  3 00
  "    "  fried..............................  3 30
Sago,  "  ..................................... 1 4<:
Salmon, salted, boiled........................ 4 00
Soup, beef, vegetable......................... 4 00
  "  chicken, boiled.......................... 3 00
  "  oyster, boiled............................ 3 30
Tapioca, boiled................................ 2 00
Tripe, soused, boiled.......................... 1 00
Flounder, fresh, fried........................ 3 30 Trout, salmon, fresh, boiled or fried...... 1 30
Fowl, boiled.................................... 4 00 Turkey, domestic, roast...................... 2 30
  "  roast.....................................  4 00
  "  fricasseed...............................  2 45
Goose, roast....................................  2 00
Lamb, fresh, boiled...........................  2 30
Liver, beef, boiled.............................  2 00
      wild,roast........................... 2 If
Turnips, boiled................................. 3 30
Veal, fresh, broiled............................ 4 00
  "    "   fried............................... 4 30
Venison steak, broiled....................... 1 35
   The rate of digestion depends on the quantity as well as the
quality of the food, for Beaumont found that while one egg was
digested in  one  hour, it required four hours to  digest eight
eggs.   The  digestion of  soups is  often very imperfect unless
they are mixed with some  such substance as bread, to retain
them in the  stomach, and prevent their passage into the duode-
num until they are properly prepared for absorption.
   We  can not leave  the consideration of the function of diges-
tion without making a few remarks  on indigestion, that  most
obscure of maladies.   If  we examine  any  of the works on hy-
giene, we find them  stored with very valuable information re-
garding the  manner in which indigestion is  to be  prevented.
Among these there are careful directions regarding the articles
which  persons so troubled should avoid.    But I have  found, in
a hospital experience of more than two years, that such rules
  What method of cooking furnishes the most digestible food ? What is the effect of quan-
tity on the rate of digestion ?  How may soups be made to digest perfectly? Give some of
the theories regarding indigestion, and the methods for palliating it.
                                 I 
60
CAUSES OF  INDIGESTION.
can  not be established, for some patients  would digest with
ease articles which were considered the most indigestible, and
which would  give an attack of colic to any healthy person,
while a meal of substances usually regarded as very digestible
would subject them to hours of torture.
  Some physiologists advise that the water  introduced into the
system should always have a temperature approaching that of
the stomach; but it is almost impossible to follow such a plan,
especially when we recall the nauseating effect of warm water
on the  majority of people.   We must therefore set  aside all
such arbitrary rules, and each person  must decide for himself
regarding the articles best adapted to  his own peculiar digest-
ive powers.
  The food should be  sufficient in quantity  and thoroughly
masticated, for if the  stomach is overloaded it can not do its
work properly.   It is no doubt wise, when a person has com-
mand of his own time, to abstain from mental or physical exer-
tion for a short period after eating.  But how few will abstain
from either, and, even if they do, they are apt to become mor-
bidly careful, and, in their anxiety to obtain perfect health, ren-
der their own and the lives of those who come in contact with
them insupportable.
  Indigestion is often a symptom of some  disease, such as an
imperfect  production of pepsin  or hydrochloric acid by  the
gastric follicles: such cases may be relieved by the use of the
missing constituents of the gastric juice as  medicines.  Regur-
gitation of bile or pancreatic juice from the  duodenum into the
stomach will also produce indigestion, by neutralizing the acid
of the gastric juice.  Cancer, and many other diseases, the con-
sideration of which wre have not the space to review, also seri-
ously interfere Avith the digestive process.
  There are peculiarities in the digestive  apparatus of some
                                       animals which are of
                                       interest  to  the physi-
                                       ologist.  An  excellent
                                       example is  afforded
                                       by ruminants, Fig. 64,
                                       Avhich   possess   four
                                       stomachs,  called  the
                                       ingluvies, or  moisten-
                                       ing stomach, b, which
  How are the digestive powers of a person to be determined ?  Of what diseases is indiges-
tion a symptom ? How is deficiency of pepsin to be treated ?  How does regurgitation of
bile act ?  Name the stomachs of the cow.
Fig. 64.
Stomachs of Ruminant. 
         RELATION OF FOOD TO LENGTH  OF INTESTIl^E.       61

receives the food from the oesophagus, a; second, the honey-
comb, or second  moistening pouch, c, from AAThich the food is
sent to the mouth, to be again chewed as the  cud, and returned
to  the  third  stomach, called the
omasum, d, from which  it  passes
into the fourth stomach, e, and final-
ly escapes at the pylorus,/.   In the
porcupine there are also four stom-
achs, while in the kangaroo there
are eight of these organs.
   The  nature  of the food has a
great influence on the character of
the  digestive  apparatus, especially
as regards its length.   In the car-
nivora  it is very short, being but little  more than a  straight
tube.   A complex elongated intestinal  canal in such  animals
Avould be superfluous, for their food is so rich in nutritive ma-
terial, and so  easily digested, that  only  a part  of the canal
Avould be used.
   In the hcrbivora, on the  contrary, an  enormous  amount of
food has to be digested, in order  to obtain sufficient nutriment
to satisfy the Avants of the animal.   Not only is the bulk very
great, but the nutritious parts are difficult of extraction, and re-
quire a more complex apparatus than that needed for the  so-
lution of such  coneentrated  food  as flesh;  consequently, the in-
testinal canal is elongated, and in those animals that require a
large quantity of nutriment, on  account  of their size, as the
Asiatic elephant, the colon alone  reaches a length of more than
tAventy-six feet, while in those Avhose food contains a very small
proportion  of nutriment, as the Arabian dromedary, Avhich
feeds on dry stubble, it reaches the enormous length of forty-
six feet.
   In Fig. 66, page 62, the casca of the common foAvl are repre-
sented ;  a being  the  oesophagus; b, the crop,  or  insalivating
pouch; c, the stomach; d, the gizzard, or masticating pouch; e,
the liver; f small intestine; g, the casca; and h, the cloaca.
  The digestive apparatus of birds, as Avell as of animals, is in-
fluenced by the nature of the food, the cassoAvary, Avhich has a
plentiful supply of highly nutritious food, having a colon one
foot in length, and tAvo casca, each six inches in length, Avhile
  AVhat is the influence of the food on the length of the digestive canal?  AVhat are the pe-
culiarities of the intestines of the herbivora ?  AVhat is the length of the intestine in the
elephant and dromedary ? Compare the length of the intestine in the cassowary and the os-
trich.  AVhat parts compose the digestive tract of birds ?
Fig. 65.
Stomachs of Kangaroo. 
62
COMPOSITION OF FAECES.
Digestive Tract of common Fowl.
the ostrich, whose food is scanty, and not
very nutritious, has a colon forty-five feet
in length, and two  casca, each two feet
nine inches long.
  We might mention many examples in
the other kingdoms and orders of ani-
mal life which would illustrate the influ-
ence of food on the length and character
of the digestive tract, but the instances
furnished are as  strong and convincing
as any  that could be  presented;  we
therefore pass to the examination of the
processes employed in the separation of
the soluble nutritious elements of the di-
gested food from those which are insolu-
ble or effete, and consequently of no use
in the human system.
                     LECTURE XIII.
           CAPILLARY ATTRACTION AND ENDOSMOSIS.
 Composition of Fceces.— Origin and Diurnal Amount of Faeces.—Intes-
  tinal Gases.— Capillary Attraction.—Examples and Explanation of
  Capillary Attraction.—Dialysis.—The Endosmometer.—Endosmosis.—
  Exosmosis.—Action of Gum in the Endosmometer.
  Absorption of the digested food commences in the stomach,
and continues throughout the intestinal canal to the anus, until
all the nutritive matter is conveyed into the system, and noth-
ing remains in  the intestines but useless residue, to which the
name of Tasces is given.
  Fceces are  composed of, 1st. Cellulose, or the woody fibre of
vegetables and grain, which, though it is digested by beavers
and many insects, and is their chief article of food, is not acted
on by the digestive juices of man and the great majority of
animals;  2d. Starch granules, which have escaped the  action
both of the saliva and the pancreatic fluid;  3d. Shreds of mus-
cular fibre;  4th. The coloring  matter of the  bile, which has
been derived from the coloring matter of the blood, and con-
tains a considerable amount of iron; 5th. Epithelium, from the
intestinal mucous membrane, and the glands  connected Avith
the digestive apparatus.
What is the composition of faeces ? 
COMPOSITION OF INTESTINAL GASES.
63
  The diurnal amount of dried fasces is  about one  and one
quarter ounces.  The apparent quantity is much greater, but
that is easily accounted for when we consider the large propor-
tion of water they contain when freshly voided.
  With the fasces certain gases pass from the intestine.   They
are, 1st. Nitrogen, derived from the air that was mixed Avith
the food during mastication and swallowed; 2d. Carbonic acid,
derived in part from the blood, and in part from the partial
decomposition  of the food during digestion; 3d. Sulphureted
and phosphoreted hydrogen, also formed by the decomposition
of food, or secreted from the blood.  They give to the gaseous
discharges of the intestine their disagreeable odor.
  In order to study the phenomena of absorption in an intelli-
gent manner, we must first examine into the nature of certain
physical forces by means of which it is  accomplished.  The
physiologists of  olden times regarded the pyloric valve with
peculiar interest, for they thought that it presided over this
function, and determined Avhat articles should be introduced
into the system, and what should be ejected as fasces.   By the
light which modern science and patient, painstaking examina-
tion and experiment have thrown on this function, we now see
clearly what the true nature of absorption is, and reason con-
cerning it just  as we would regarding any ordinary manufac-
turing process.
  The force called into play during the act of absorption, both
in plants and animals, is capillary attraction, by which is meant
the power tubes of  narrow calibre possess of raising  a liquid
above its proper level Avhen they are placed in it.
  It may be illustrated by heating a piece of thermometer tube
near its centre, and turning it while it is in the flame so that it
may receive the  heat equally  on all  sides.  When it has  at-
tained a bright red heat it  is drawn out, and a perfect tube
finer than a hair is obtained, which, being touched to a drop of
water, raises it  to a considerable height.
  The height to Avhich a tube can raise a liquid depends  on
the diameter of its  bore, as may be illustrated  by placing in
water tubes of diameters varying from half an inch to the
finest that can be made, when it is found that the finer the
tube the greater the height to which it can raise the liquid.
  All liquids are not raised by tubes of glass, but  some, such
  AArhat is the diurnal amount of faeces ?  What are the intestinal gases ? What is their or-
igin ? What was the old idea regarding the pyloric valve ?  What is capillary attraction ?
What determines the height to which a tube can raise a liquid ?  Are all liquids raised by
tubes ? 
64
CAPILLARY ATTRACTION.
Fig. 68.
Elevation of a wetting Liquid.
Depression of a non-
 getting Liquid.
                               as mercury, are depressed. The
                               true cause of the phenomena
                               of  capillary movement  seems
                               to be electricity; for if the con-
                               ditions of the liquid and tube
                               are  examined, they  are  found
                               to  present opposite electrical
                               states when the liquid is raised,
                               and  similar  electrical   condi-
                               tions when it is depressed.  If
                               the  fluid rises Ave say that it is
                               by  virtue of the  property  it
                               possesses of wetting the tube ;
and  since different fluids possess this poAver to different de-
grees, it sometimes seems as though the tubes possessed an in-
herent poAArer Of selection, permitting a passage to some fluids
and denying it to others.
  The selecting power,  as it is commonly called, can be con-
trolled by very simple  physical causes.   For  example, if Ave
take a bundle of ordinary lamp-wick and moisten it with wa-
ter, and then dip it into a mixture  of oil and Avater, the latter
Avill rise, but the oil will not.   If we perform the experiment
by first wetting the wick Avith oil, the oil will rise and the Ava-
ter will be left behind.
  Though a capillary tube can be prepared in such a manner
as to raise a specified liquid, it can  not establish a continuous
flow through its interior Avhen it  is  broken off short  of the
point to which it raises  the liquid.   The fluid, under such cir-
cumstances, merely rises to the broken extremity of the tube,
and remains stationary.
  If we take measures  to remove the liquid from the broken
extremity as fast as it rises, either by means of a piece of blot-
ting-paper, or by evaporation, combustion, or any other suita-
ble method, the fluid in  the tube will rise to take the place of
that Avhich  is removed, and a current can so be established.
  The statement made in the previous paragraph may  also be
applied to membranes, which may be regarded, since they are
more or less porous, as  consisting of an  infinite number of ex-
ceedingly short capillary tubes, which extend from one surface
of the  membrane  through  its texture  to the  other surface.
  How is capillary attraction explained? What is meant by the selecting power of tubes ?
Give some examples.  Will liquids flow continuously through short capillary tubes ? Under
what circumstances can continuous currents be established in tubes ? AVhat is the composi-
tion of membranes ? 
THE  ENDOSMOMETER.
65
Fig. 69.
When such membranes  are formed into a sac or bag, Avhich is
filled Avith a liquid that can Avet its pores, the fluid quickly
permeates the membranous barrier; and if it is removed as fast
as it reaches the opposite side, the receptacle will soon become
empty.                <
 ^  This property is now applied in some manufacturing opera-
tions to  the separation  of fluids  from each other, by placing
them on the opposite sides of a membrane, and adjusting the
conditions  necessary to  produce the desired result.  It is de-
scribed in chemical Avorks as the method by dialysis.  A very
simple illustration of this action is to take a mixture of alcohol
and water, place it in a bladder, and suspend it in a current of
air.  The water in the mixture quickly Avets the bladder, pass-
es through and is evaporated from the  exterior surface of the
membrane, while the alcohol, having little or no affinity for the
membranous structure, remains in the bladder, and  is finally so
perfectly freed from water as to be almost absolute or pure.
   The power membranes possess of causing certain liquids to
move through their tissue is altogether  independent of press-
ure, and  w7ill, as Ave shall hereafter see,
go on without restriction against the
greatest  pressures we  can  call  into
action.
   The above fact is illustrated by the
experiment represented  in the  adjoin-
ing figure.   The apparatus is called an
endosmometer, and consists of a small
bladder filled with alcohol, and attach-
ed water-tight  to  a narrow tube two
or three  feet in length, and placed in a
large vessel of pure  Avater.   The  wa-
ter, having a great affinity for the mem-
brane, passes through it, but, as soon as
it  reaches the  interior surface  of the
bladder,it is dissolved away by the alcohol; at the same time,
the alcohol moves in the opposite direction, viz., to the exterior
of the bladder, and is in its turn dissolved by the water on the
outside;  but as the water wets the bladder  better than the al-
cohol, it  passes  through its  texture more rapidly, and conse-
quently there is an accumulation  of liquid  in the  interior  of
 How do membranes act on liquids ?  Upon what condition does the movement depend ?
How is this principle employed in manufactures? How may alcohol be concentrated?
Does pressure influence the action of membranes on liquids ? Describe the endosmometer.
How does the endosmometer act?
                             E
The Endosmometer. 
66               ENDOSMOSIS AND  EXOSMOSIS.

the bladder; this is at once relieved by the fluid rising in the
tube, and finally reaching the upper extremity, Avhere it forms
large drops, and may be collected in considerable quantity as
it falls.  The tube may be lengthened to an indefinite extent,
the liquid still rises  in a perfectly unobstructed manner until
the column is so high as either to cause the bladder to burst,
or rupture the ligature that binds it to the tube.
  It must not be supposed that the movement of the alcohol
into the water, endosmosis, as it is called, will go  on for an in-
definite period, for it has a limit, which is reached as soon as
the liquid in the interior and that on the exterior of the blad-
der are  composed of equal proportions  of alcohol and water;
it then ceases, and can only be renewed by adding more  alco-
hol to the contents of the bladder, or Avater to the liquid on its
exterior.
  If, instead of placing alcohol in the interior, we place it on
the exterior of the bladder, and fill it with water, the move-
ment still goes  on, but it is in the  outward direction; conse-
quently, instead of there being an accumulation of liquid in the
bladder, there  is a  loss; it becomes  partially  empty.   This
movement is called exosmosis, in contradistinction to that pre-
viously described.
  Substituting a solution of gum for the alcohol, we find it acts
in the same manner.  When it is placed in the  bladder, and
the instrument is immersed in water, endosmosis  is produced;
and when the arrangement is changed as described in the last
paragraph, there is exosmosis.
                     LECTURE XIV.

                         ABSORPTION.

Mechanism of Absorption in Plants.—Functions of the various Parts.—
  The ascending Sap.—The Force it exerts.—Descending Sap.—Descrip-
  tion of a Villus.—Lacteals.—Receptaculum Chyli.—Thoracic Duct.—
  Stomach Absorption.— Villus or Intestinal Absorption.—Action of Mes-
  enteric Glands.—Effect of Disease of Mesenteric Glands.

  Understanding clearly the  physical forces just described,
we can intelligently pass to the study of absorption; and since
plants afford us highly interesting illustrations of this function,

  Where does the liquid accumulate when the alcohol is in the bladder? How long will the
endosmosis continue? Under what circumstances is exosmosis  established?  Can other
fluids be substituted for the alcohol ? 
ABSORPTION  IN PLANTS.
67
 it AviU be to our advantage to describe first the mechanism and
 method of absorption in plants, and then apply the information
 we have gained to the examination of the same apparatus in
 animals.
   Commencing at the root of a plant, Ave find that the terminal
 roots originate in small sacs or bags, called spongioles, which
 have a thin membranous wall; from the spongiole a fine ligne-
 ous tube passes along the root, trunk, and branch, to  a twig,
 and finally terminates in a leaf, where it subdivides into capil-
 lary vessels called veins, which are distributed to the upper
 surface of the leaf.  Turning to the under surface, a return sys-
 tem is formed, by which the sap  that has ascended from the
 spongiole is conveyed to the  roots.
   On the under surface of the leaf a great number of open-
 mouthed cells or cavities, called stomata, are connected Avith the
 return system  of veins; it is  their province to present the sap,
 under the most favorable conditions, to the action of the as-
 cending currents of air,-which are  rising through the leaves of
 the plant, and cause the eA'aporation of a portion of the water,
 and consequent concentration of the sap.
   The fluid in the spongioles is a concentrated solution of gum-
 water.   The exterior of the spongiole is in contact Avith moist
 soil, the water of which contains various salts  and other solid
 materials, dissolved from the  strata through which it has perco-
 lated.   Through the Avail of the spongiole the gum-water pass-
 es, and, at the same  time, the  water of the soil moves in  the op-
 posite direction; but, since the latter moA^es with greater rapid-
 ity than the former, there  is an  accumulation of fluid in the
 spongiole, and it rises in the  tube, as in the experiment in en-
 dosmosis, described  in a preATious paragraph.
   The spongiole, therefore, is the  source of power which  com-
 pels sap to  rise to the highest twigs of the loftiest trees, and it
 seems almost incredible that so delicate a mechanism  should
 produce such wonderful results.
   The ascending sap is A^ery dilute, containing a little gum and
 the  salts which were  absorbed in solution  in water by  the
 spongiole; it passes up the vessels of the plant to the upper
 surface of the leaf, where it is brought, under the influence of
 light, in contact with the carbonic acid of the air.   Under these
i conditions, water and carbonic acid are decomposed, oxygen is
 set free, and gum formed.   Ammonia and other substances
  Describe the mechanism of absorption  in plants.  What are stomata? What is their
 function ?  Describe the action of the spongioles. What is the composition of  ascending
 sap ?  How is it changed in the leaf? 
68
THE  VILLUS DESCRIBED.
are also acted on; but it will simplify our explanation if we
disregard them, and merely trace the course of the gum.  From
the upper surface the sap turns to the under side of the leaf;
the dilute solution which was formed on the upper  surface is
concentrated by the  action of the stomata, and a moderately
strong solution of gum-water formed, which, as it passes cloAvn
the tree, is called the descending sap; it  nourishes the tissues
of the plant, and, finally reaching  a spongiole,  aids in intro-
ducing fresh materials.
  The force with which sap rises in plants is uncontrollable, as
may be demonstrated by cutting off a grape-vine near its  root
and attaching a pressure-gauge securely to the cut extremity.
The sap will rise from the root into the  cut trunk and gauge
until a  pressure of ten or twenty atmospheres is reached, and
it would show a far greater force, but it is impossible to make
joints which  can bear the strain.   The only practicable limit
to the pressure the rising sap can be made to  exhibit is the
fragility of the apparatus employed, and there is no doubt but
that it would take place  against fifty atmospheres as easily as
against five.
  Passing from plants to man, we find that the villus of the in-
testine is the analogue of the  spongiole of the plant; and just
as the spongiole  absorbs  from the earth, water and nutriment,
so the villus, and also the blood-vessels of the gastric mucous
membrane, absorb from  the digested food its  nutritive parts,
and introduce them into  the system (p. 42, Fig. 57).
  A villus is most readily described by commencing  at the in-
terior and passing outward; following this plan, wTe find in the
interior the termination of a lacteal tube, which forms a species
of elongated bulb; outside of this there is a layer of blood-ves-
              Fig. 70.
Villus showing Termination of the Lacteal Tube
 What is the composition of descending sap?  How is it finally disposed of?  How may
the force of the ascending sap be demonstrated J1 How much pressure will it exert?  What
organ in man is analogous to the spongiole ?  Describe the parts which compose a villus.
Fig. 71.
Villus showing Blood-vessels. 
ABSORPTION IN ANIMALS.
69
Villi showing External Cylindroid Epithelium.
Fig. 73.
sels and muscle-cells, covered               Fig.72.
by columnar or cylindroid ep-
ithelium, Avhich comes in con-
tact with the chyle formed in
the intestinal canal during di-
gestion.
  From the villus the lacteal
passes through one  or  more
mesenteric  glands, and, unit-
ing with other lacteals, forms
larger   and  larger   trunks,
Avhich  finally  enter  a  long
tube half an inch in diameter and four or five inches in length,
called the receptaculum  chyli, which lies
on the Jumbar vertebras.
  A delicate tube, called the thoracic duct,
passes from the upper extremity of the re-
ceptaculum chyli, and, traversing the tho-
racic cavity, empties into the left subcla-
vian vein at its junction with the internal
jugular, as  is shoAvn in the figure, 1 being
the arch of the aorta;  2, thoracic aorta;
3, abdominal aorta; 4, arteria innominata;
5, left carotid;  6, left subclavian ; 7, vena
cava descendens; 8, venas innominatas; 9,
subclavian  vein; 10, great  vena  azygos;
11,lesser vena azygos;  12,  receptaculum
chyli; 13,thoracic duct;  14,the cuiwe of
the thoracic duct; 15, the right lymphatic
duct.
  For convenience of description, the func-
tion of absorption may be studied under
two  divisions: 1st. Stomach absorption;
2d. Villus  absorption.  In   the first the
veins  of the stomach take  up by endos-
mosis the nutritive materials Avhich have
been converted into chyme by the  action
of the gastric juice; such  bodies, there-
fore, as fibrin, albumen, casein, and gluten
enter directly into the blood-vessels as soon as they are digested.
  How is the fluid that has entered the villus disposed of?  Where and what is the recepta-
culum chyli—the thoracic duct?  What is the  course of the thoracic duct?  Into what
does it empty ?  What are the divisions of absorption ?  Describe stomach absorption. What
articles of food are absorbed in the stomach ?
 
/


      70           ACTION OF THE MESENTERIC GLANDS.

        In villus absorption, on the  contrary, after the  chyle has
      reached the interior of the lacteal tube, it is obliged to pass
      through the  mesenteric glands, AAmich are connected with the
      lacteals.   Before entering the glands the chyle is composed of
      albumen and fat, but after it has passed through them it con-
                             tains  fibrin  and large nucleated  cells,
                             called chyle corpuscles.
                               These corpuscles are of great inter-
                             est, for they are the mother cells from
                             which blood discs are born.  In chil-
                             dren the mesenteric  glands are  often
                             diseased, the peculiar substance called
                             tubercle, which is formed in the lungs
                             in  consumption, being  deposited in
                             these glands in  very young persons.
                             Whenever this occurs, the function of
                             the glands is seriously interfered with;
      chyle corpuscles and fibrin are  not produced; the blood and
      muscles are not properly nourished, and the child is pale and
      emaciated; its strength  grows less and less every day, until
      death supervenes.
        Leaving the mesenteric glands, some of the lacteals enter the
      veins of the intestines, but the great majority pass to the recep-
      taculum chyli, so that the oils and fats follow a very circuitous
      route before they finally enter the blood.
                      LECTURE XV.

                            BLOOD.

Properties of Sap.— Of Blood.— Variations in the Appearance of Blood.
  — Composition of Blood.—Influence of Sex and Climate on its Composi-
  tion.—Function of Water.— Of Albumen.— Of Extractive.— Of Fats.—
  Of Salts.— Of Fibrin.— The Clot.—Action of Mesenteric and Lymphat-
  ic Glands.—Red Blood Discs.^r Wliite Discs.—Hcematin.— Globulin.—
  Plasma.—Serum.

  All plants and animals possess a circulating nutritive fluid
or juice; in plants it is called sap; in  animals, blood.  The col-
or of the nutritive fluid varies, being sometimes white, and oft-

  What"change is impressed on chyle during its passage through the mesenteric glands?
What are chyle corpuscles ?  What is the effect of disease of the mesenteric glands ?  Do
the lacteals empty into the receptaculum chyli ?  AVhat is the nutritive juice of plants__of
animals ?  What are the variations in color ?
 
COMPOSITION OF BLOOD.
71
en colorless; but in animals it is generally either red or blue,
according as it is arterial or venous.   When first drawn from
a free opening, blood is always perfectly fluid; but after it has
stood for a time a portion turns  solid, forming a mass called a
clot, Avhich floats in the fluid part, to which the name of serum
is given.  While yet in the arteries  and veins, the blood re-
tains its fluidity, and consists of minute red cells, which float in
a tawny-colored liquid called plasma.
  The total weight of blood in the system was determined by
an extensive series of experiments on decapitated criminals to
be equal to one eighth of the weight of the  body.  It  is con-
tinually changing, since it is the  channel through which the in-
gesta are introduced into the system.   The nature and  extent
of the change  may be realized when Ave reflect that the total
weight  of this  fluid in the body, according to  the results of the
experiments spoken of above, is less than  twenty pounds, and
the  annual amount of ingesta is more than three  thousand
pounds.
  There are slight variations in the nature of the circulating
juice in the  different  sexes, the blood of males being heavier
than that  of  females.   Climate  also produces  its  influence,
causing that of the inhabitants of tropical regions to be dark-
er colored than that of persons living in  cold countries.  In all
animals it possesses an odor peculiar to  each species; by add-
ing a little sulphuric acid to a sample of blood obtained from
an unknown source, it gives out the peculiar odor of the  ani-
mal  from which it was obtained, enabling us to determine its
origin.
  The reaction of human blood  is alkaline;  and since  it con-
tains a  considerable  amount of  nitrogenized substances, it is
very prone to undergo decomposition, giving off a disagreeable
putrid odor.
  The substances AAThich enter into the composition of blood
are
         Water................................................. 784   "|
         Albumen__.......................................... 70
         Extractive and fat...................................  6.77 )■ Plasma.
         Salts..................................................  6.03
         Fibrin..................................................  2.20 J
         Discs.................................................... 131.00
                                        1000.00
  AVhat is the appearance of freshly-drawn blood ?  How does it change ?  What is the to-
tal weight of blood in the body ?  How was it determined ?  Is the composition of the blood
fixed ?  What is the influence of sex on the composition of blood—of climate ? How may
the odor of blood of different animals be evolved?  What is the reaction of blood?  What
is the composition of blood ?  AA'lnit is plasma ? 
72     ORIGIN OF  THE ALBUMEN, EXTRACTIVE, AND FAT.

  Water forms the basis of the fluid; it is subject to slight va-
riations in quantity, depending on its use.  If it has been re-
cently introduced  into the stomach, the proportion may rise
considerably above the figures in the table;  if it has not been
taken for  some time, the percentage will fall below the stand-
ard quantity.
  The albumen is the representative of the nutritive group;
out of it all the tissues of the body are formed to a greater or
less extent; it is derived from the albumen, fibrin, gluten, and
casein which were introduced into the stomach as food.   The
constitution of these substances is almost identical, at least as
far as the number and character of atoms composing them is
concerned.  Their conversion into the albumen of the blood is
therefore very simple, and is probably accomplished by merely
rearranging their component atoms so that they are grouped in
the same  manner, and consequently out of substances which
possess different physical properties and qualities one homo-
geneous material is formed.
  The extractive is  a term applied to certain substances con-
tained in  blood, and nearly  all the fluids and tissues of the
body.   It appears to be  formed of a number of organic mate-
rials, which give characteristic properties, such  as  a definite
color  or odor, to the substances they compose.  The  extract-
ives haATe  as yet been examined only to a very slight extent,
and but little is known  concerning them.  The proportion in
the solid ingredients of some of the fluids of the body is very
large, and the study of this class of substances offers a more
promising field of discovery to the physiologist than any other
department of his science.
  Fats are derived from  the oily and fatty substances  employ-
ed as food; they belong  to and represent the respiratory class,
and are used in the system to produce the heat which enables
all animals to keep their temperature either above that of the
medium in which they live, or at some fixed degree.
  As has  been already stated, the fats are in part turned into
sugar in the liver; in this state they are probably more prone
to undergo oxidation in the systemic and pulmonary blood-ves-
sels.   Those portions which are not converted into  sugar are
stored away in the cellular tissues  of the body, and form the
fat of the  animal.
 What is the function of water in the blood ? How may the proportions vary ? What
does albumen represent ? From what is it derived ?  What is the extractive ? What is the
function of fats ?  What is the action of the liver on fats ? 
            FUNCTION OF THE SALTS IN THE BLOOD.         73

   The most important salts are chloride of sodium, phosphate
of lime, and phosphate of soda.   The common salt, or chloride
of sodium, is, as Ave have seen, used to furnish the hydrochloric
acid of the gastric juice, and the soda of the bile.  When the
absorption of the digestive material is completed, these bodies
meet again in the general  circulation, reunite, and form salt,
which may be again decomposed to furnish another supply of
acid and soda.  A very small amount of salt can in this man-
ner be caused to furnish an  almost unlimited supply of digest-
ive juices; and though man continually renews the salt in his
system, there are  many animals, such as  the buffalo, which  re-
sort at a special season of the year to regions Avhere salt depos-
its exist, and obtain a  supply of that material which lasts for
many months.
   Phosphate of lime is employed to nourish the bones and
teeth.   In the early period  of the life of an animal very large
supplies of this substance are required, and Ave find that milk
contains a considerable proportion of bone phosphate.  The di-
urnal amount of this phosphate in the milk of the mother is
greater than that introduced into her system  each day in her
food; under these circumstances, the milk phosphates are de-
rived from the osseous tissues of the  parent;  consequently,
during the nursing period, when the bones of the young are be-
ing consolidated, those of the mother steadily lose phosphate
of lime, and the osseous tissues of the child are  literally con-
structed out of those of the parent.
   Phosphate of soda presents one peculiarity Avhich is of great
interest as  regards the movement of carbonic acid gas in the
body.   If pure water is taken, it is found that at a given tem-
perature and pressure it will absorb a definite volume  of this
gas; but if to the water phosphate of soda is added, it then
takes up a far larger A*olume of gas than it dissolved when in
the pure condition.   The presence  of phosphate of soda in the
blood therefore enables it to dissolve and hold in solution all
the carbonic acid  evolved in the body.
  Though the fibrin appears to be in such small  proportion,
it is one of the most important ingredients.   It  possesses the
poAver of spontaneous  coagulation, and  may be  obtamed by
whipping freshly-drawn blood with a bundle of twigs; under

 AVhat are the salts in the blood ? For what purpose is the chloride of sodium employed?
How is the percentage of salt in the blood maintained? For what purpose is the phosphate
of lime employed ?  How is the large proportion of phosphate of lime in the milk obtained ?
What property does the phosphate of soda impart to the blood?  How may fibrin be obtain-
ed from blood ? 
74                COMPOSITION OF  THE CLOT.
these circumstances, the fibrin, as it coagulates, attaches itself
to the twigs, and is obtained as a light yellow material in the
form of a stringy mass.
   The clot produced when blood coagulates is composed of the
fibrin of the  fluid, which, as it takes on the solid condition,
forms a network of fibres in which the discs are entrapped.  At
first the clot  appears to occupy the whole mass of the fluid,
but, as  soon as the fibrin is coagulated, it commences to con-
tract, and the size of the clot steadily diminishes until it is
quite small and hard.  The contraction of the fibrin in the clot
is the last living act of the blood.
   Fibrin is produced in the system at the rate of sixty-tAVO
grains per hour, but the quantity in the blood is unchanged,
since the muscles  appropriate it as fast as it is formed.   If
chyle is  examined after its passage through the  mesenteric
glands  or lymph, after it has been  subjected to  the action of
the lymphatic glands, they are both found to be very  rich in
fibrin, while albumen has disappeared; we therefore  conclude
that fibrin is produced out of albumen by glandular action.
          F.  75             The discs are shaped like a coin, be-
                        ing  circular and flat; they are  about
                        3YP of an inch in diameter, and ttjj-oo
                        of an inch thick.  The cell wall of the
                        disc is composed of a substance called
                        globulin; the fluid  content  is hcema-
                        tin, Avhich contains a very large amount
                        of iron, and  is of a deep red color.
                          If freshly - drawn  blue  or  venous
                        blood is placed under a jar containing
                        oxygen, it turns red, becoming arterial.
  Human Blood Discs 500 Diameters.   rxw '  ~\      '   1   ,  n   -1 • °  t   -,
                        liiis change is due to the discs  absorb-
ing oxygen, the hasmatin having an affinity  for that gas, and
yet not  uniting with it, but merely dissolving it, to surrender
it up again.  The  union of oxygen with hasmatin  is so weak
that we may  readily separate  them  by placing the  fluid under
an air-pump jar, and exhausting, when the oxygen is immedi-
ately set free.
   In addition to the red corpuscles or discs, there  are large

  Which constituents of blood form the clot? Describe its formation.  What is the rate of
production of fibrin in the body?  What change does chyle undergo in passing through the
mesenteric glands?  What change do the lymphatic glands impress on lymph?  Describe
the discs.   AVhat is their diameter? Of what is their cell wall composed?  What is the
name of the fluid?  What  is the effect of oxygen on venous blood?  Is the oxygen closely
united with the hasmatin ?  How may it be separated ?
 
ORIGIN OF  THE BLOOD DISCS.
75
spheroidal cells floating in the blood, which differ from the red
discs not only in color, but also in their specific gravity; they
move along in the current of the circulation in a tardy manner,
seeming to cling to  the Avails of the capillaries  and smaller
bloodwessels.
   The white discs contain a number of nuclei, Avhile the red
discs do not have  any nucleus, though  at times they appear,
under the microscope, to be  nucleated; but it is a deception
produced by the figure of the disc, the  surfaces  of which are'
not perfectly flat, like those of a coin, but slightly curved, being
sometimes concave and at others convex.
   The red discs originate from  the  Avhite discs, to AAThich the
name of mother cells or corpuscles is  given; the method of
production is by rupture, the Avhite corpuscles bursting or their
Avails dissolving, and the nuclei, being set free, assume the red
tint, and become full-grown  red blood  corpuscles.  We may
therefore say that the red discs are the nuclei  of the  white
discs, and are set free when the mother cells are destroyed.
   The Avhite discs in their turn, originate from chyle corpus-
cles Avhich Avere formed in the mesenteric glands.   When these
glands are diseased, as is frequently the case in young children,
the  muscular and  other tissues of the body become soft, the
blood loses its  color, and the lips and skin no longer present
the natural ruddy hue of health.   These changes are all due to
the fact that the diseased gland  fails to produce chyle corpus-
cles with sufficient rapidity, and  consequently the number of
red discs in the body is greatly reduced.
   As Ave view the blood under the microscope, we find that it
consists of separate discs floating in  a fluid; to this liquid the
name of plasma is given.  It contains all the other constituents
of the blood, and differs from serum in that the latter fluid has
lost its fibrin during  the formation of the clot.
   It has been estimated that twenty millions of red blood discs
are destroyed in each pulsation of the heart, and there is every
reason for believing that the estimate is correct.  On this basis,
a man, in the course of eighty years, has created and destroyed
in his system such a vast number of millions of millions of
these organisms, that if Ave Avere  to place them side by side so
as to touch each other, they would form a line long enough to
go around the earth more than ten thousand times.
 Describe the white discs.  AVhat is their relation to the red discs ? What is the origin
of the white discs ?  Why are the red discs reduced in number in disease of the mesenteric
glands?  AA'hat is the difference between  plasma and serum? How many discs are de-
stroyed by each pulsation of*the heart? 
76                THE  CIRCULATORY SYSTEM.

  Astronomy has its wonders, and dismays us with distances
which the mind  of man can not grasp, telling us that though
light moves with a velocity of thousands of miles in a second,
there are stars so far distant that their light does not reach the
earth for years after it  is emitted by the star.  Physiology also
has  its marvels; and though the number  of blood discs  pro-
duced in the system is almost incredible, it falls into insignifi-
cance when we compare it with the total number of cells pro-
duced in the body during a lifetime.
                     LECTURE XVI.
                   THE BLOOD-VESSELS.
The Divisions of Blood-vessels.—Their Composition and Character.— Or-
  der of Development of the Blood System.—The Heart described.— The
  Pericardium and Endocardium.— Muscular Tissue of the Heart.—Its
  Cavities, their relative Position.—Rate  of Pulsation.— Valves.—Their
  Function.— Valvular Sounds.—Diseases of the Valves.
  From the consideration of the  character and properties of
the blood, we now pass to the study of the vessels in which it
circulates.
  The blood-vessels are divided into three classes, viz., arteries,
veins, and capillaries.  The arteries have thick walls, and are
empty after death, their coats being so elastic as to enable them
to retain  the circular tube-like form.  Owing to  this peculiar-
ity, it  was  formerly supposed that  they  conveyed air to all
parts of the body.  The veins, on the contrary, have such  thin
Avails that they collapse when empty; they are also provided
Avith valves, which open toward the heart.  The walls of both
arteries and veins are composed of three coats, an exterior lay-
er  of  condensed  cellular  tissue, and  an interior thin smooth
membrane.  Between these there is a layer of elastic fibrous
tissue, which contains involuntary muscle  cells.  Some physiol-
ogists speak of it as the muscular coat, while  others call it the
elastic coat.
   When  the  arteries in the living body are  cut, either by in-
tention or accident, the blood Aoavs from them in  a strong in-
termitting current, the impulses  corresponding to the pulsations
  What are the three classes of blood-vessels ?  What is the difference in appearance be-
tween the arteries and veins after death? To what is this due?  What are the three coats
of blood-vessels ? What is the character of the flow of blood from veins and arteries when
wounded ? 
THE  HEART  DESCRIBED.
77
 of the heart.   The only way to stop the flow from the large ar-
 teries is to tie them with a stout silken string called a ligature.
 When a vein is cut the flow  of blood is dark blue, that from
 the artery being crimson or arterial.   The nature of the flow
 also is different, being continuous, and not possessing the jerk-
 ing character which marks the flow of blood from an artery.
   The large veins and arteries continue to subdi\dde until the
 branches are so small as to escape ordinary vision.  To these
 minute vessels the name of capillaries is given;  they are about
 3^_of an inch in diameter, and constitute the channel of com-
 munication between the arteries and veins.
   If Ave wTatch the development of the blood system in the egg
 of a  frog, or in any  suitable  embryo, Ave find  that the blood
 first appears;  after that, the capillaries; then the larger blood-
 vessels; and, finally, the largest blood-vessel undergoes a dilata-
 tion in one part, the walls in  this region becoming thickened,
 until a perfect heart is formed, the object of which is to regu-
 late the flow of fluid through  the vessels.
   The heart differs in its character in different creatures: in
 some it contains a single chamber; in oth-
           •    -i                                  Fie 76
 ers, two;  m  others, three; but in all the       ^kiQ
 animals of the class mammalia  it contains       !xW
 four caA'ities.
   In shape the heart resembles a cone, be-
 ing four or five inches in length, and three
 or four in diameter at its base or largest
 part.  The size of the heart of any individ-  CHrf
 ual is said to be equal to the size  of the  \S\
 closed fist, but this estimate  is of  course
 merely  approximate,  and liable  to very
 great error.  It lies on its side in the tho-
 racic caArity, across the median line, Avith
 the apex  pointing downward and to  the
 left, the base being uppermost, and  on the right  side  of the
 sternum or breast-bone.
   The heart is covered exteriorly by a stout fibro-serous mem-
 brane  called the pericardium, AAhich  closely resembles the  se-
 rous or synoAual membrane of joints;  and Avhen Ave remember
 the ligaments Avhich form the joints, and the fibrous nature of

  How is the flow to be stopped ?  What are the capillaries ?  What is their diameter ?
 What is the order of the development of the blood system ?  How does the heart differ in
 different animals ?  What is its shape ? What is its size ?  What  is its position ?  On
•which side is the apex ?  By what is the heart covered ? What is the  nature of the pericar-
 dium?
The Heart. 
78              THE CAVITIES OF THE HEART.

the pericardium, it is not at  all surprising that rheumatism, a
disease almost peculiar to joints, should often attack the heart,
the constitution of which so closely resembles that of a joint.
  The interior of the heart is lined by a serous membrane, the
continuation of which also forms the inner layer or coat of the
blood-vessels;  it is called the endocardium.
  The middle layer of the heart is composed of striated mus-
cular tissue, arranged in bands, which are very prominent in
its interior, crossing each other in all directions.   In  man the
cavities are arranged in  such a manner as to form two distinct
hearts, each of which is composed of two cavities, one at the
base, the other at the apex.  The cavity at  the base is called
the ventricle;  it is conical in form.
  To the division of the heart which lies on the right side of
that organ the name of  the right heart is given; it receives the
blue venous blood from the  great veins of the body, and pro-
pels it to the lungs to be arterialized; it is therefore called by
many authors the pulmonic heart.  The left division is known
as the left heart; and since it receives the crimson arterial blood
                         from the lungs, and drives it through
                         the great arteries of the system, it is
                         called the systemic heart.
                           In the dugong, the right or pulmo-
                         nic heart is separated from the left or
                         systemic heart, as is illustrated in the
                         figure.  A is the aorta;  D, the right
                         auricle;  E, the right ventricle;  F, the
                         pulmonary  artery; K, the left  auri-
                         cle ; and L, the left ventricle.
                           The twTo  divisions of the heart are
                         arranged so that the auricles lie  side
       Heart of the Dugong.       ^ g^ an(J form ^ ^age Q£ ^ Qr.
gan, while the ventricles are in a similar position  at the apex.
Since the auricles  receive the  blood sent to the organ, and
empty it into the ventricles, acting as mere  assistants to them,
they are not required to  exert any very great force;  conse-
quently their walls are very thin, being but little more than
one eighth of an inch in thickness.
   The ventricles, on the contrary, and especially the left, force

  Why is the heart liable to rheumatism ? What is the endocardium ?  What tissue com-
poses the middle layer of the wall of the heart ?  Name the cavities of the heart.  What
names are given to the right side of the heart? What to the left ? What is the relative po-
sition of the auricles and ventricles ?  What is the duty of the auricles ? How thick are
their walls ?
 
                 THE VALVES OF THE HEART.               79

the blood into the arteries, and deliver it to the  capillaries;
their walls, therefore, are more substantial, that of the left ven-
tricle being often three quarters of an inch thick.
   It is estimated that the left ventricle contracts with a force
equal to 13 lbs., the pressure of the blood in the aorta, or great
systemic  artery which conveys the fluid to the  other arteries,
being 4 lbs. 3  oz.
   The number of pulsations in a minute varies with the age of
the  individual, being  130 to  140  at birth, 80  to  85 during
childhood, 70 to 75 during  adult life, and 50 to  65  in old age.
It is also more frequent in females than in males.   If we make
due allowance for these variations, and estimate the amount of
blood discharged by the ventricle into the aorta at three ounces,
we find that at the age of eighty years the heart of a man has
moved a mass of blood sufficiently large to build a column fif-
ty feet square at the base, and tAvelve hundred feet high.
   The auricles and ventricles are provided with valves which
compel the blood to flow in a definite course—that  is, from the
auricle into the ventricle in  each division.  We  may  study
them to advantage in their proper order.  The first valve lies
in the right or pulmonic heart, between the auricle  and ventri-
cle ; it is composed of three divisions, which close the opening
between the auricle and ventricle perfectly when they come in
contact with each other.  This is called the tricuspid, or three-
lipped valve.
   The  second valve   closes the
opening between the  right  ven-
tricle and the pulmonary artery
which conveys the blood from the
heart to the lungs to  be arterial-
ized;  it  is  composed of  three
half-moon-shaped divisions, which
meet  and touch when the valve
is shut.
  In  the adjoining figure, from
Wilson's  anatomy, 1 is the right
auricle; 2, its  appendix;  3, vena
cava descendens; 4, vena cava as-
cendens;  5, fossa  ovalis;  6, Eu-         Eisht side of the  Heart
  Which cavity of the heart has the thickest walls ?  What is the force exerted by the left
ventricle ? What is  the-pressure of the blood in the aorta ?  What is the rate of pulsation
at birth—childhood—adult life — old age?  What is the volume of blood moved by the
heart in a lifetime?  AVhat is the direction the valves force the Blood to follow? Describe
the first valve, its name, composition, position; the second valve, name, composition, posi-
tion.
 
80
THE  VALVES  OF THE HEART.
stachian valve;  7, mouth of coronary vein;  8, coronary valve ;
9, auriculo-ventricular opening;  a, right ventricle; b, c, cavity
of ventricle; d,pulmonary artery; e,f, tricuspid valve; g, the
long columna carnea; h, the long moderator band; i, columnas
carneas  of the right curtain; h, I, tendons; m, \7alve of pulmo-
nary  artery, or  semilunar A7alve; n, apex of appendix; o, left
ventricle; p, the ascending aorta; q, its arch;  r, descending
aorta.
   The function  of the tricuspid A^alve is to  prevent the blood
flowing backward into the auricle after it has been forced into
the ventricle, while the auricle is expanding and the ventricle
contracting.  The semilunar valves  in the same manner close
the opening into the pulmonary artery, and prevent the blood
returning while the ventricle is expanding.
   In the systemic heart, the valve between the auricle and ven-
tricle is composed of two folds or divisions, and from  its fan-
cied resemblance to a bishop's mitre is called the mitral valve;
it prevents the passage of the blood  back into the auricle dur-
ing the contraction of the left ventricle.
                                    The aorta, or artery given
                                 off from  the left auricle, is
                                 closed by a valve similar to
                                 that found at the mouth of
                                 the pulmonary artery;  it is
                                 called  the   semilunar, or
                                 fourth ATalve.
                                    The figure represents the
                                 left side  of the  heart;  1  is
                                 the interior of the left auri-
                                 cle ; 2, cavity  of the appen-
                                 dix ; 3, mouths of right pul-
                                 monary veins;  4, sinus  into
                                 Avhich left pulmonary veins
open;  5, left  pulmonary veins;  6,  auriculo-ventricular open-
ing ; 7,  coronary vein;  8, left ventricle;  9, cavity of ventricle ;
a, mitral valve;  b, columnas  carnas; c, columnas carnas  of in-
ner surface; d, arch of aorta; <?,  pulmonary artery;  /, ductus
arteriosus; g, left pulmonary artery; h, right ventricle;  i, point
of right appendix.
   In the following figure, which represents the heart cut across
Left Side of the Heart.
 What is the function of the tricuspid and right semilunar valves ?  Describe the third
valve, its name, composition, position;  the fourth valve.  What are the duties of the mitral
and left semilunar valves ? 
SOUNDS  PRODUCED DURING THE HEART'S  ACTION.     81
 its base to show the valves, t, t, t is  the  tri-      _Fig.so.
 cuspid valve;  m, m, the mitral; e,f the sem-
 ilunar Aralves of the aorta and pulmonary ar-
 tery.
   The two sets of semilunar valves have their
 margins perfectly free, and close the openings
 into the aorta  and pulmonary artery by their
 contact.  But  the case  is different with  the
 mitral  and tricuspid  valves;  their margins are  attached by
 small^ tendons to muscles which arise from the walls of the
 ventricles, and which aid in working these valves in a proper
 manner.  These muscles and tendons of the valve are beauti-
 fully shoAvn in the heart of a  sheep, as  well  as the relative
 thickness of the auricles and ventricles, and the muscular bands
 in the latter.
   During its  action the heart  emits peculiar  sounds, which
 are not produced, as was formerly thought, by  the contraction
 of its muscular fibres, but are  caused by the  passage of the
 blood through the valves, and their sudden closure.
   By the  character of these sounds we may with ease recog-
 nize the contractions  of the auricles  and ventricles.   The au-
 ricles  at the base contract at the  same moment, as is readily
 proved by vivisections on animals; the sound produced is rep-
 resented by  the syllable lubb.   This  is followed by the con-
 traction of the ventricles, which also  move together, and pro-
 duce a sound represented by the syllable  tup, shorter, quicker,
 and  sharper than that produced by the auricles.
  The first sound is caused by the passage  of the blood through
 the mitral and tricuspid valves, and terminates by their sudden
 closure.  The  second  sound is produced by the blood flowing
 through the  semilunar valves  of the  aorta and  pulmonary  ar-
 tery, and ends with their  sudden closure, by the fluid forcing
 the valves back as the ventricles begin to expand, just as the
 valves of a forcing-pump act under similar circumstances.
  In disease of the valves these sounds are changed, the modi-
fication being generally due  either to the formation of a depos-
it on the vahre, and its consequent thickening and roughening,
thus obstructing the passage of the fluid from the auricle into
the ventricle, or to its failure to close the opening betAveen the
 What valves have free margins? What organs are attached to the mitral and tricuspid
valves? AVhat is their function? What is the nature of the sound produced by the auri-
cles—by the ventricles ? How are they produced ? How are the sounds modified by dis-
ease ? To what are the modifications due ?
                               F 
82
THE PULMONARY BLOOD-VESSELS.
two cavities, permitting the blood to pass backward through
the opening into the auricle.
  When these abnormal conditions exist, the character of the
sounds is changed, and a buzz or murmur accompanies the first
long sound or the second short sound.  The valves are often
both rough and deficient; in such a case the murmur is heard
with both sounds.
  Not only can the experienced physician determine that the
valves are diseased, but he can also state, with almost absolute
accuracy, in  which vah^e the  disease exists.  This  is accom-
plished in  part by finding where the murmurs are most in-
tense, and by noticing other phenomena, such as the pulsation
of the veins.
                     LECTURE XVII.
               the  blood-vessels— Continued.
Pulmonary and Systemic Blood-vessels.— Course of the Pulmonary Ves-
  sels.— The Aorta.—Its Divisions.—Its Termination.— The Cardiac Ar-
  tery.—Arteria Innominata.— Common Carotid.—Subclavian.—Arteries
  of the Upper Extremity.—The Intercostal Arteries.— The Phrenic.— Cce-
  liac Axis.—Superior Mesenteric.— Other Abdominal Arteries.
  From the study of the heart we pass to the  examination of
the blood-vessels.  They are divided into two classes: 1st. Those
connected with the circulation of the blood in the lungs, called
pulmonary vessels;  and, 2d. Those engaged in the conveyance
of nutritive material to the various  tissues of the body, to
which  the name of systemic A^essels has been given.
  The pulmonary  vessels consist  of the  pulmonary artery,
which  takes its origin from, and opens  into, the right ventricle;
it divides almost immediately into the right and left pulmona-
ry arteries, one of which passes to the right, the other to the
left lung, conveying the blue venous blood to  those organs to
be arterialized.
  The right pulmonary artery enters the right lung at its root,
and divides immediately into two branches, the upper division
giving a branch to the middle lobe.   The left pulmonary artery
enters  the left lung, and divides into two branches, which con-
vey the blood into the two lobes of which it is composed.
  Each of the large  divisions of the pulmonary artery continue
  Into what two classes are the blood-vessels divided ?  Name the vessels of the pulmonary
system.  Describe their course. 
 
Fig. 81.
PAROTID ClAHO-----::sjim duct
        EXTERNAL JUGULAR VE//V-
        WTERMAL JUGULAR VEIN-
              CLAVICLE-
           i   VEIN
SUBCLMAN\fiRTERX.
AXILLARY l*"™"^
BBACWALi*"™*
*.„,., iARTERY
RADIAL |  v£m_
          CWIS SEA/fS. *fe.

The Circulatory System. 
THE  AORTA AND ITS BRANCHES.
85
to subdiATide in the tissue of the lungs, until they finally term-
inate in capillary vessels, which are  about 3^-5 of an inch in
diameter, enabling the discs, which are 32V0  0I* an mch m di-
ameter, to pass through them Avith ease.  The capillaries form
an intricate network on the walls of the air-cells of Avhich the
lungs are composed; they then unite and originate larger ves-
sels, Avhich have the composition and structure of veins, and ul-
timately form four pulmonary veins, which pass from the lungs
to the heart, and enter  the left  auricle at the  base of the
organ.
  The systemic  vessels are more difficult  of description than
the pulmonary, since they are more numerous and intricate.
  The great artery which receives the blood  from the left ven-
tricle is called the aorta; it is about one inch in diameter, and
is curved, forming an arch.  The first part of the vessel passes
upward, and is called the ascending aorta; the second curves
and passes backAvard to the left side of the vertebral  column:
it is called the arch; while  the  third  portion passes  down-
ward, lying partly on the left side and partly on the vertebral
column:  it is called the descending aorta.
   The first part of the descending aorta lies in the thoracic cav-       £
ity; it is consequently known as the thoracic  aorta.  It then
passes through an opening in  the diaphragm, or muscle which
separates the two great cavities of the trunk, into the abdomi-
nal cavity, Avhere it is called the abdominal aorta.   In the low-
er part of this cavity it  divides into tAvo branches, the right
and left  iliac arteries, Avhich supply the lower extremities with
blood.
   The branches  of the aorta may be studied  under the follow-
ing  divisions: 1st. Those  of the ascending portion; 2d. Those
of the arch; 3d. Those of the thoracic; and, 4th. Those  of the
abdominal portion.
   The branch of the ascending aorta is the cardiac artery:  it
is given  off close to the heart, so that its mouth is closed by the
semilunar valves of the aorta when they open to give the blood
passage into that vessel.
   The branches of the arch  are, 1st. The arteria innominata,
which is  about one and one half to  two inches in length; 2d.
The left  common carotid;  and, 3d.  The left  subclavian.  On

  Where are the pulmonary  capillaries ? How many pulmonary veins are there ?  What
is the name of the great systemic artery ? AVhat is its diameter ?  What is its shape ? Into
what portions is it divided ? AVhat are the divisions of the descending aorta ?  How does it
terminate?   AVhat is the first branch of the aorta?  What are the branches  of the arch?
Describe the arteria innominata. 
86
THE  CAROTID ARTERIES.
Carotid Arteries.
the right side the common carotid and subclavian are formed
by the bifurcation of the arteria innominata.
   From  their origin the common carotids and subclavians on
both  sides pursue  a similar course.   We shall therefore  de-
scribe the course of the vessels of the right side.
                                    The common  carotid, a,
                                  passes  obliquely  up  the
                                  neck  toward the  angle of
                                  the  lower  jaw, where  it
                                  reaches a position about op-
                                  posite the Adam's apple; it
                                  divides into two branches,
                                  the  external .and internal
                                  carotids.  The external car-
                                  otid, b, passes up on the out-
                                  side of the skull, giving off
                                  a number of branches, which
                                  convey blood  to  the  scalp
                                  and other tissues of that re-
                                  gion ; the most important
                                  of these are the occipital, o,
                                  which passes  to  the back
 of the head; the maxillary and  temporal, y, g, passing to the
 temples  and the side of the  head.   The internal  carotid, c,
 passes toward the apex of the petrous part of the temporal
 bone, where it enters the cranial cavity through a canal in that
 bone.
   In man, the  canal which contains  the  internal  carotid is
 curved,  so  that  the  force of t]ie pulsation of the ventricle is
 lessened by compelling the blood to follow a curved course.
 In many of the herbivora, in whom the head is kept for a long
 period in a dependent position while feeding, the carotid splits
 up into a number of small branches as it passes into the skull,
 producing  a similar result in a more perfect manner.
   After entering the cranial cavity the  internal carotids unite,
 and  form a series of communicating vessels at the base  of the
 brain, called the circle of Willis, from which that organ is sup-
 plied with blood.*  The object of this free  communication of
 the carotids from both sides is to produce an equality in press-
 ure of blood on all parts of the brain, and also a free and equal
 supply  in case either carotid should be  injured.
   Describe the course of the common carotid.  What are its branches ? Describe the ex-
 ternal carotid, its course and branches ; the internal carotid, its course. What are the pe-
 culiarities  in the course of this artery in man and animals ?  Describe the circle of Willis. 
          BLOOD-VESSELS OF THE UPPER EXTREMITIES.       87

  The subclavian passes outward to the upper extremity, to
supply it with blood.  In the middle of its course it lies on the
first rib, and under the clavicle; hence  the name subclavian: it
gives  off a number of branches, which supply the muscles
about the shoulder; one of these, called the mammary, passes
down the front of the thorax, and communicates with an artery
given off by the external iliac in the groin.
  Reaching the  armpit, the subclavian becomes the axillary
until it gains  the inner  edge of the biceps muscle, when  it is
called the brachial;  it follows the inner  edge  of the biceps
down the arm to the elbow, where  it bifurcates, sometimes
above, but usually below that joint, into the ulnar and radial
arteries.
  The ulnar artery, as its name indicates, lies on the ulnar bone
in its course down the fore-arm, Avhile the radial lies on the ra-
dius.  A third artery, called the interosseous, a branch of the
ulnar artery, also passes down the fore-arm, lying between the
two bones and on the interosseous ligament.
  From the wrist the radial passes around the metacarpal bone
of the thumb  into the palm of the hand, lying on the metacar-
pal bones  of the fingers, and uniting Avith the ulnar artery so
as to form the palmar arch, from which the branches are given
off to the fingers, called the digital arteries, Avhich run along
the outer and inner border of each finger.
  Owing to the free communication of the ulnar and radial ar-
teries in the palm of the hand, wounds  of either of these ves-
sels, or of the  palmar arch,  are apt to cause a  considerable loss
of blood; and it  is necessary always to tie both ends of the cut
artery, or, if there is difficulty in finding them, to tie the brach-
ial high  up in the arm.
  In Avounds  of other arteries it is sufficient to tie the end of
the artery nearest to  the heart, as there is but very little chance
of a flow of blood from the other extremity; but  in the  case
of the ulnar and radial, the free communication through the
palmar arch renders the precaution of tying both  ends  abso-
lutely necessary.
  The branches  of the thoracic  aorta  are the intercostals, one
to each  rib.   They run in a groove on the under and inner
edge of  the rib, so that they are protected from Auolence, and

  What is the course of the subclavian ? What are its- branches ?  Where does it become
axillary ? Describe the  brachial.  What are the terminal branches of the brachial ? De-
scribe the ulnar, radial, interosseous arteries.  How is the palmar arch formed ?  Where is
it? AArhat are its branches ?  AVhat is the peculiarity of wounds of the arteries of the fore-
arm ?   AA'hat are the branches of the thoracic aorta ? How are they protected ? 
88          BRANCHES OF THE ABDOMINAL  AORTA.
Fig. 83.
can only be wounded by a knife, the edge of which is turned
upward, and the blow struck so that the point of the knife
passes upward, and not downward, as is usually the case when
a person is stabbed in this region.
  The first branch given off by the abdominal aorta is the
phrenic.   It takes its origin from the great arterial trunk, just
as it is passing through the diaphragm, and, entering the tissue
of that muscle, supplies it with blood.
  The second branch of the aorta is called the ceeliac axis.  It
is not more than half an inch in length, and divides  into the
                            gastric,  splenic, and hepatic, each
                            of which supplies the organ Avhose
                            name it  bears.   The splenic and
                            hepatic, in addition to supplying
                            the spleen and liver, also  give off
                            branches to the stomach and pan-
                            creas.
                              The third  great branch of the
                            aorta is  the  superior  mesenteric.
                            It conveys blood to all the small
                            intestines, and to  the large intes-
                            tine, with the exception of the de-
                            scending  colon, sigmoid flexure,
                            and rectum.
                              The remaining branches of the
                            aorta are  the  renals,  of which
                            there are two, one on each side:
                            they pass to  the kidneys; the in-
                            ferior mesenteric, which passes to
those parts of the large intestine not  supplied by the  superior
mesenteric; the spermatic, which pass to the testicles; and the
lumbar branches, which are analogous to the intercostals of the
thoracic cavity: they run  around the  abdominal walls,  and sup-
ply the muscles which form them.
  What is the. first branch of the abdominal aorta? Where  is it given off? What does it
supply ?  Describe the coelic axis. What are its branches ?  What do they supply ? What
is the third branch ?  What does it supply ? What are the remaining branches ? What do
they supply?
Superior Mesenteric Artery. 
BLOOD-VESSELS  OF THE LOWER EXTREMITY.        89
                     LECTURE  XVni.
                the blood-vessels—Continued.
 Common Iliac Arteries.—Internal Iliacs.—External Iliacs.—Arteries of
  the lower Extremities. — Veins of the Head.— Of the Upper Extremity.
  — Tlie great Veins of the Chest. — Veins of the Lower Extremities.—Por-
  tal Vein.— The Course of the Blood.
   We  have already seen that the aorta terminates below in
the common iliac arteries, which pass to the right and left low-
er extremities.   The branches of both of the common iliacs are
the  same on each side; we shall therefore  only describe those
of the right side.
   The right common iliac passes to the brim of the pelvic cav-
ity.   It is about three inches in length, and divides into the in-
ternal and external iliac arteries; the former passes doAviiAvard
into the cavity of the pelvis, and  supplies the organs  it con-
tains with blood.  Some of its branches pass out through open-
ings in the walls of the cavity, and supply the muscles about
the buttocks and hips: its terminal branch, the pubic, supplies
the genital organs.
   The external iliac lies on the brim of the pelvis, and passes
out  of  the abdominal cavity to the thigh.  As it lies  on the
pubic bone, it gives off two branches, one of which is called the
epigastric, which passes up the anterior wall of the abdominal
cavity, and communicates with the mammary, a branch of the
subclavian, so  that  when  the external iliac is  tied, blood  can
reach the lower extremity through this circuitous channel.
   Reaching the thigh, the  external iliac becomes the femoral,
Avhich gives off in its upper part a large branch called the pro-
funda, that passes backward, and  supplies  the muscles  on the
back of the thigh with blood.  In the upper third of the thigh
the femoral is  superficial, and all necessary operations are usu-
ally  performed  on it in this part.   In the middle third it is
deeper, and gradually passes to the back part of the thigh.  In
the loAver third of the thigh the femoral becomes  the popliteal
  AA7hat are the divisions of the iliac arteries ? What is the  course of  the  internal iliac ?
What  does it supply ?  What is the course of the external iliac ? AVhat are the divisions of
the femoral artery ?  AVith what artery does the epigastric communicate ? In what artery
does the femoral terminate ? 
90
THE A'EINS.
artery, which lies on the smooth surface of the posterior lower
part of the femur.  Opposite the head of the tibia the poplite-
al divides into the anterior and posterior tibial, the first pass-
ing down the leg in front of, and the  second behind the inter-
osseous ligament.   In the foot, the arteries of the leg form the
plantar arch,  similar  to  the  palmar, which gives off digital
branches to the toes.
  The veins commence in the capillaries in  Avhich the arteries
terminate.   In the brain the venous blood flows into large cav-
ities formed by the membranes of that organ, and called sinuses;
from these it is finally conveyed to the internal jugular Areins,
and carried by them down the neck to the shoulder, and deliv-
ered into the venas innominatas.  The blood from the outside
of the  head is brought to the same point by  the  external jugu-
lar  vein.
  The veins of the upper extremity commence in the digitals
which  form the  deep ulnar and  radial.  These  unite at  the
elbow, and, receiving some of the superficial  vessels of the fore-
arm, form the brachial, which, passing up the arm to the arm-
pit, becomes axillary, then subclavian, and finally unites with
the internal jugular to form the yena innominata.
  The right and left venas innominatas, uniting, form the vena
cava descendens, which conveys the blood to the  right auricle.
  In the loAver extremities the  veins of the  foot form the tibi-
als, which, uniting at the back  of the knee-joint, become pop-
liteal, and  then femoral, external iliac, common iliac, and final-
ly vena cava  ascendens, which  empties  the  venous blood into
the right auricle.
  In addition to the veins we have mentioned, there  are great
numbers of small superficial vessels, but they all empty sooner
or later into one of the large veins of the extremities or trunk.
In  the upper extremity there is  a superficial vein, called the
cephalic, which passes up the arm, conveying blood from some
of the  superficial vessels of the fore-arm to the subclavian.   In
the lower extremity there is a similar vessel, which commences
at the large toe, and is called  the  saphenous vein:  it carries
blood  from the superficial vessels of the lower extremity to the
upper  part of the femoral, into which it enters.
  In the abdominal cavity the renals are the only veins of the

  What are the arteries of the leg—of the foot ? What is the origin of the veins ?  What
are the veins of the head—of the upper extremity ? What veins form the vena innominata—
the vena cava descendens? Name the veins of the lower  extremity.  What veins form the
vena cava ascendens ? Describe the superficial veins.  Describe the veins of the abdominal
organs. 
THE  DISCOVERY OF  HARVEY.
91
large organs, except the hepatic, that empty directly into the
vena cava aseendens.
   The veins from all the other viscera, viz., the  stomach, spleen,
pancreas, large  and small intestines, unite together to  form a
short trunk of  large diameter, called the portal, Avhich enters
the liver and there subdivides, causing the blood from the ca-
pillaries of all the abdominal organs except the kidneys to pass
through a second system of capillaries in the liver; these, coa-
lescing, form the hepatic, or vein of the liver, which empties the
blood into the vena cava ascendens.  The portal circulation of
the liver is  copied to a certain extent in the kidney, but we
shall defer  the  description  of the  renal circulation until Ave
take up the study of the kidneys.
   From the anatomy of the circulatory system, we pass to the
examination  of the  course  the blood  follows in  its passage
through the different parts of that apparatus.
   The great discovery of the course  of the circulation of the
blood was niade about two hundred years ago by Harvey.  He
founded his doctrine on the  fact that the valves of the  veins
will only alloAV the fluid contained in those vessels to flow in
one  direction, viz., toward the heart;  and the valves in the
heart also impress upon the blood a definite movement, from
the right auricle through the tricuspid to the  right ventricle;
then  through the  semilunar valves and pulmonary artery to
the lungs; back by the pulmonary veins to the left auricle and
ventricle;  then  through the  aorta to the systemic capillaries,
and back by the systemic veins to the heart, thus forming a
figure 8, the meeting of the two circles being in the heart.
   The discovery of Harvey was a grand step in the advance-
ment of physiology and medicine, but  it supposed that  these
movements were all caused by the contraction of the heart.
   Direct experiment has shown that the force exerted by that
organ is not sufficient to propel the blood through the capilla-
ries ;  and we find, in attempting to  inject these minute A'essels,
that a far greater  force than that exerted by the heart is re-
quired to drive  the most subtle injections into them; and they
suffer so severely,  that  even in the  most successful injection
many capillaries are ruptured.
   In the explanation of the portal circulation of the liver, Har-
  What is the portal vein ? What is the portal circulation ?  What was the ancient idea re-
garding the arteries? What is the true course of the circulation? Who was the discover-
er ?  When did he live ?  On what facts did Harvey found his doctrine ? Is the force ex-
erted by the contraction great enough to drive the blood through the capillaries into the
veins ? 
92         draper's  theory  of THE  CIRCULATION.

vey's doctrine is altogether unsatisfactory; and if we consider
the cases of monsters born without hearts, or, rejecting all oth-
er facts, reflect for a moment  on the order in which the circu-
latory apparatus is developed, the heart being the last member
of the system to  appear, we find that though Harvey  has
taught us the  course through which the blood flows, he does
not satisfactorily explain the causes of its movement.
                     LECTURE XIX.
                 CIRCULATION OF THE BLOOD.
Harvey's and Draper's Theories.—Affinity of Liquids for Tubes.—Princi-
 ple of Venturi.— Causes of the Circulation in Systemic and Pulmonary
 Vessels differ.—Perfection  of Draper's  Theory.—Course of various Ar-
  ticles to different Parts of the Body.
  A rational and satisfactory  exposition of the causes of the
circulation was first given by Professor^ J. W. Draper, and, aft-
er many years  of opposition from various  physiologists, has
been finally accepted as  the true explanation of the movement
of the blood.
  Draper's theory places the force which causes  the blood to
circulate in the capillary vessels, and shows that the true cause
of the movement is  capillary attraction.  The arguments by
which this doctrine is supported are  as follows:
  1st. The heart does not exert sufficient force  to  drive the
blood through the capillaries and veins ; 2d. The portal circula-
tion is carried on Avithout a heart;  3d. The order of develop-
ment  of the  circulatory system, and the  existence of acardiac
monsters, shows that the blood  can circulate independently of
a heart.
  In the vegetable world, we find that plants have a circulating
juice  or sap which  is moved without the agency of a heart.
In  these  organisms, the circulating fluid is  forced to an alti-
tude which is sometimes to be measured by hundreds  of feet,
and is therefore pj?opelled against a resisting pressure, compared
with which the resistance to the movement of the blood in man
falls into insignificance.
  In plants the circulation commences in the fine capillary ves-
sels in the roots, and terminates in fine capillaries in the leaves.

  Where does Harvey's doctrine fail ? What is Draper's theory of the circulation ? How
is the sap circulated in plants ? 
the  action of the heart.
93
Fig. 84.
Motion in a Capillary Tube.
Fig. 85.
No heart  is employed.  The force generated by capillary at-
traction and  endosmosis ansAvers  all the requirements;  Avhy,
therefore,  may  not capillary  attraction be the  cause of the
movement of the blood in animals, as well as of sap in plants i
   In order to  explain in a satisfactory manner the moA^ement
of the blood in the A^essels containing it, we must first deA'ote a
brief space to the  examination of certain physical phenomena
upon Avhich the circulation depends.
   If there are two  liquids in the tube a v, and the liquid a has
a strong affinity for its walls, but loses
it as  soon as it  reaches the point c, it
is evident that there  will be a flow
from  a through c to v, and the move-
ment will  continue until a  is ex-
hausted.
  The principle of Venturi also has
its influence in producing the  circu-
lation.  If a current of fluid is flow-
ing through the tube a b,  and   a
smaller tube, c  d, empties into it,  a
movement from the smaller into the
larger tube Avill be established.
  Applying these  and other  phys-
ical phenomena, of Avhich Ave have
spoken, to  the  explanation of the
systemic circulation, Ave find that  it
is the function of the  heart to keep
the arteries filled with blood, that  there may always be a free
supply of fluid  delivered to the capillaries.  As it enters the
capillary ATessels the blood is arterial, the discs being laden Avith
oxygen.   The tissues  through Avhich thfe capillaries pass'are
composed of carbon, which, at certain times and in certain allo-
tropic conditions, has an intense affinity for oxygen.  The discs
containing the oxygen consequently move fonvard to deliver
it to the atoms of carbon Avhich attract them.
  As soon as the oxygen has been surrendered to  the carbon,
and carbonic acid formed, the blood no  longer has  any affinity
for the Avails of the  capillary tubes,  and the conditions that
then exist  are similar to those afforded in the case of the exper-
iment Avith the liquids a v, and the tube c.
  As fast, therefore, as the arterial blood becomes venous, and
 If a liquid has an affinity  for the walls of a tube, and gradually loses it, what is the result?
What is the principle of Venturi? AVhat is the duty of the heart? What is the action in
the capillaries ?
Principle of Venturi.
\ 
94
CIRCULATION  IN  THE CAPILLARIES.
loses its affinity for the walls of the capillaries, it is pressed for-
ward into  the veins by the fresh portions  of arterial blood,
which move up to unite Avith the carbon of the tissues.   If this
Auew  of the cause of the  circulation is correct, it follows that
the passage of the blood through the smallest capillaries should
be  continuous, and free from the  pulsation that exists in the
arteries,.
  Examining the circulation in a frog's foot under the micro-
scope with a  power  of about 200, Ave find that not only does
the condition of continuous motion spoken of exist, but from
time to time  the blood moves backAvard toward the  arteries:
                             Fig. 86.
t
Capillary Circulation of a Frog's Foot.
a movement which, of course, it is perfectly impossible for the
heart to produce, but which is readily explained by the loss
of affinity of certain  atoms of carbon, and increased affinity in
others, attracting the blood more  powerfully, and diverting it
from its previous course.
   The supply of venous blood to the veins by the capillaries
is therefore continuous and without intermission, and the flow
of the fluid in these vessels is  free from all pulsatile character.
According to the doctrine of Harvey, the right auricle exerts

  What facts corroborate Draper's theory?  How does the blood move in the capillaries?
What is the nature of the movement in the veins ? What was Harvey's idea regarding the
function of the right auricle ?
 
     THE THEORIES  OF HARAHEY AND DRAPER  CONTRASTED.   95

an  exhausting action on the  venous blood;  but, if AATe reflect
for a moment on the yielding nature of the Avails of the veins,
we see that any such exhausting process is perfectly impossible.
  The presence of valves in the veins, on the existence of Avhich
Harvey founded his doctrine of the circulation, does not in any
way contradict or interfere Avith the theory of Draper, for their
function is still the  same; and, since they are found altogether
in the extremities, Avhere the veins are subjected to  great press-
ure during the violent contractions of the surrounding muscles,
they are absolutely necessary in order to prevent the regurgi-
tation of the blood back upon the capillaries.
  In the pulmonary circulation, the conditions which produce
the movement of the blood are exactly the opposite of those
which cause the systemic  circulation.  The blood delivered to
the pulmonary capillaries is laden with carbonic acid; the air-
cells, on the walls of which these capillaries are  distributed, are
filled with oxygen gas, which endosmoses through the Avails of
the vessels, and, interchanging with the carbonic acid of the
blood, arterializes it.
  As fast as the venous blood surrenders its carbonic acid in
the pulmonary capillaries,  it also loses  its  affinity for  their
Avails, and is consequently forced out into the pulmonary veins
by  new  portions  of venous blood, which press  forward in the
capillaries to exchange their carbonic acid for  oxygen.  The
method of operation in the lungs is similar to that in the sys-
temic ATessels, but the conditions  are different—not  only as re-
gards the causes of the circulation, but also as regards the con-
tents of the great blood-vessels;  the arteries  of the lungs con-
taining venous, and the veins arterial  blood, while the system-
ic arteries contain arterial, and the veins venous blood.
  The great advantages of Draper's theory have gradually been
recognized.   The fact that  it affords  a  clear, intelligible ex-
planation of the portal circulation in the  liver and kidney, and
accounts for the circulation in acardiac monsters and such ex-
ceptional cases, gives it a force and power in Avhich the doc-
trine of  Harvey is very deficient.  At the present time, there-
fore, Harvey is  acknowledged as the  discoverer of the course
of the  circulation, but to Draper is  aAvarded the discovery of
the causes of the circulation of the blood.
  We  lnwe hoav described the divisions  of food, and the  func-
  AVhat is the function of the valves of the veins ? How do the causes which produce circu-
lation in the capillaries differ in the pulmonary and systemic vessels ? Is  the blood in the
pulmonary artery arterial or venous ?  What peculiarities of circulation does Draper's theory
explain that Harvey's doctrine can not? 
96   STAGES OF  INTRODUCTION  OF FOOD  INTO THE  SYSTEM.

tions of digestion, absorption, and circulation, Avhich  are  en-
gaged in preparing and delivering nutriment to the different
tissues of the body; we are therefore prepared to pass to  the
examination of the organs of secretion  and excretion.   Before
Ave take up the consideration of this division of our subject, we
shall devote a short space to a synoptic  revieAv of the functions
already studied.   I have found such tables to be of great value
to students, enabling them to  fix the  steps of the  introduction
of nutriment into the tissues  more firmly in their minds, and
to attain a connected idea of the various functions, and their
relations to each other.
   The manner in Avhich the following  tables  are constructed
enables the student to select  any article of food, and  trace it
step by  step to  some organ or tissue.   Many may  object to
this  system, urging that the substance under question does  not
retain its qualities through all the processes to Avhich it is sub-
jected, and therefore any such method is useless.  I would an-
SAver that  it is not intended to  assert that articles of food re-
tain their character during the various  operations of digestion
and  absorption; but as the experience  of a number of years
has taught me that this tabular arrangement is of great value
to students, it is introduced here for their advantage and con-
venience.
   In making use of the synoptic table, any special article of
food, as, for example, fat, may be traced to any part of the  sys-
tem.  It passes through the various divisions  of the digestive
and  absorptive  apparatus until it reaches the large  lacteal
trunks, where one portion enters the blood by the mesenteric
veins and vena  cava ascendens, while the other part reaches it
by the receptaculum chyli and vena cava  descendens.   In the
heart the two divisions are reunited; sent to  the lungs to re-
ceive oxygen;  then conveyed  to  the   aorta,  from which  its
course to the head, upper or lower extremities, or great abdom-
inal organs, may be traced to its return to the  right auricle.
   By studying this table in  connection with a few examples
of different articles of food, the  student will soon become  per-
fectly familiar with all the  leading facts  in digestion,  absorp-
tion, and circulation; for, with  the passage  of an article from
point to point, he soon connects the changes which it under-

  Trace the course of albumen from the mouth into the right ventricle—the course of sugar
to the vena cava ascendens—the course of fat to the right auricle—the  course  of gluten to
the right hand—fibrin to the left hand—fat to the brain—albumen to the feet—salt  to the
kidneys. Trace the blood from the feet to the hands—from the hands  to the brain—from
the brain to the kidneys—from the kidneys to  the liver. 
STAGES  OF  INTRODUCTION  OF  INGESTA  INTO THE  SYSTEM.
1st, Water.
  Mouth.
 Pharynx.
CEsophagus.
 Stomach.
V
           2d, Salts.
Phosphate Lime, Chloride Sodium, etc.
  Mouth.
 Pharynx.
CEsophagus.
 Stomach.
     3d, Nutritive Articles.
Albumen, Fibrin, Casein, Gluten.
    Mouth, masticated.
        Pharynx.
       CEsophagus.
Stomach, digested by Gastric
          Juice.
4th, Respiratory Articles.
Carbo-hydrates = Starch and Sugar.
Mouth, masticated and mixed with
             Saliva,
            Pharnyx.
          CEsophagus.
Stomach, where Saliva acts, convert-
  ing them into Lactic Acid, which
    assists the  Gastric  Juice
      in  Stomach digestion.
Q
          \/
      Converted into
      —Chyme.—
Absorbed by Gastric Vein
\
         \/
         into
     Portal Vein.
Capillaries of the Liver.
Vena Cava Ascendens.
Hydro-carbons =: Oils and Fate
       Mouth, masticated.
           Pharynx.
          (Esophagus.
 Stomach, not digested, but pass
   through the Pyloric Valve
            into the
   Duodenum, converted into
          —Chyle-
  Absorbed by Intestinal Villi.
           Lacteals.
       Mesenteric Glands.
Lacteal Trunks, which empty into

             Receptaculum Chyli.
               Thoracic Duct.
              Subclavian Vein.
              Vena Innominata.
              Vena Cava Descen-
                    dens.
Mesenteric
  Veins.  /
  Right Auricle.
 Tricuspid Valve.
 Right Ventricle.
Pulmonary Artery.
     Lungs.
 Pulmonary Veins.
   Left Auricle.
  Left Ventricle.
     Aorta. 
COURSE OF BLOOD  FROM  THE AORTA TO DIFFERENT TISSUES AND  ORGANS.
            1. Innominata.
Right Common Carotid.
                  I
Internal Caro-
     tid.
   Circle of
    Willis.
    Brain.
   Sinuses.
 Internal Jug-
 \   ular.
External Caro-
     tid.
  Muscles of
Face and Scalp.
External Jug-
    ular.
  Subclavian
  Subclavian.
   Axillary.
   Brachial.
Ulnar and Ra-
dial.  Digitals.
  Capillaries.
Ulnar and Ra-
  dial Veins.
Brachial Veins.
Axillary Vein.
Subclavian Vein
         V
Vena Cava Descendens.
J
  Gastric.
 Stomach
Gastric Vein.
   AORTA.
3.  Cceliac Axis.
      Splenic.
      Spleen.
   Splenic Vein.
5. Right Common Iliac.
Hepatic.
---\/
 Portal Vein.
        Liver.
    Hepatic Vein.
Vena Cava Ascendens.
Internal Iliac.
Pelvic  Organs
 and Muscles.
Internal  Iliac
    Vein.
               V
   Superior Mesenteric Artery.
Intestinal Branches and Capillaries.
        Mesenteric Veins.
           Vena Porta.
             Liver.
          Hepatic Vein.
    v Vena Cava Ascendens.
     External Iliac.
        Femoral.
        Popliteal.
  Ant. and Post. Tibial.
      Plantar Arch.
        Digitals.
Ant. and Post. Tibial Veins
     Popliteal Vein.
     Femoral Vein.
   External Iliac Vein
/
 Common Iliac Vein.
Vena Cava Ascendens.
           V
      Renal Artery.
     Kidney Branches.
Malpighian Tuft Capillaries.
      Efferent Vein.
Convoluted Tube Capillaries.
       Renal Vein.
   Vena Cava Ascendens. ,
Right Auricle. 
ACTION OF SPHEROIDAL CELLS.
99
goes at each step, and they all become associated together in
his memory.
   Having completed the examination of the nutritive process-
es, we next pass to the study of the mechanisms by which the
effete materials that have arisen during the action of the velyi-
ous tissues  of the body are removed  from the  system; Ave
therefore  commence the consideration of the organs of secretion
and excretion.
                      LECTURE XX.
                  SECRETION AND EXCRETION.
Formation of Secretions.—Structure  of Glands.—Action  of Spheroidal
  Cells.—Filtration.— The Mammary Gland.—Its Changes and Diseases.
  — Colostrum. — Organs  of Excretion.—The Skin.— Composition and
  Function of the Skin.—Its Appendages.—Its Glands.—Their Functions.

  Secretion  and  excretion are accomplished by means  of
glands, which are all constructed on the  same principle.  The
simplest form of gland is a tube, lined on the interior  with a
species of mucous membrane, composed either in part or Avhol-
ly of spheroidal epithelium; the membrane is freely supplied
with  blood by an extensive and intricate  system of blood-ves-
sels.
  Spheroidal cells are always employed Avhen the gland is in-
tended to produce a* secretion containing  extractive; they act
by  absorbing and removing from the blood substances which
would, by accumulating in the system,  become deleterious and
produce  disease.  After the cell has reached its adult  size, its
walls either deliquesce or burst, and surrender their contents
to aid in producing the secretion.   The substances formed by
cell action are usually  very rich in carbon and hydrogen, being
often fatty in their nature.
  With  the exception of the extractive, the other constituents
of a secretion pre-exist in the blood, and are separated by filtra-
tion from the capillary plexus on the walls of the tube.
  The glands which may be with propriety  classified as se-
creting are those connected Avith digestion, Avhich have already
been  described, together Avith the properties and functions of

  How are secretions formed?  Describe the simplest form of gland. AVhat is the peculiar
function of spheroidal cells? AVhat is the character of the bodies separated by cell action?
How are the remaining constituents of the secretion separated? Where are the secreting
glands found ? 
100
THE  COMPOSITION OF THE SKIN.
Fig. 87.
Section of Mammary
    Gland.
Fig. 88.
their secretions.  To these we may add the mamma1 in the fe-
male, the testicles of the male, the  lachrymal, and some other
small glands which  have special functions in connection Avith
certain organs, which will be described hereafter.
  The mammary gland is constructed on the same plan as the
salivary  glands, being composed of a number of lobules, the
              ducts  of which converge toward the nipple.
                These glands undergo change at the  time of
              menstruation, becoming  hard and somewhat swol-
              len.  In pregnant women they also undergo con-
              siderable increase in  size toward the close  of the
              period of gestation, the  milk often appearing be-
              fore the birth of the child.  The mammary gland
              is peculiarly liable to cancer, the deposit taking
              place Avith greater frequency in the breasts than
              in any other organ.
                The first portions of milk discharged from the
              nipple after delivery contain  a great number of
                  large cells, called  colostrum   corpuscles.
                  They seem to give to the milk a puigative
                  property, which enables it to remove from
                  the intestines of the newly-born infant  the
                  meconium, or foetal bile  Avhich has accumu-
                  lated during the last months of intra-uter-
                  ine life.
                     The organs  of excretion are the  skin,
                  lungs, and kidneys, to which we may add
                  the spleen, liver, and some small glands con-
nected with special  functions.
   The skin consists of two distinct layers.  The external, com-
posed of pavement epithelium, is continually reproduced  as it is
worn away by contact with rough substances, and is called the
cuticle.   The internal layer is called the cutis vera:  from it the
cuticle originates.  The skin is very freely supplied with blood:
it contains two sets of glands, one of which removes  water,
salts, and soluble substances, while the other secretes oily bod-
ies.  Many appendages, as hair, nails, and  horns, are  attached
to the skin, and are described with it.
   The vitality of the integument is so great that it may with-
out difficulty be transplanted from one place to another, as is
  Describe the mammary gland.  Describe the changes to which it is liable.  What dis-
ease is common in this gland ?  What are colostrum  corpuscles ? What property does the
first milk possess ? Name the organs of excretion.  What are the layers of the skin ? What
are the appendages of the skin ?
Colostral Corpuscles of Milk. 
TRANSPLANTATION OF TISSUES.
101
frequently done by surgeons in
the performance of such taliaco-
tian operations as the formation
of a  neAv  and perfect  nose to
take the place of that  member
when it is destroyed by disease.
   In F'kj. 89, a is a representa-
tion of a  specimen  in the Hun-
terian Museum, in which a hu-
man tooth was transplanted into
the comb of a hen, and  in the course of
a few days became attached and grew.
In b, a cock's spur was transplanted to
the comb of a hen, where it grew rapid-
ly, owing to the superabundant nutri-
tion of the part.  In the third specimen,
c,  in  Avhich the  spur was successfully
transplanted to the comb of a cock, it
grew with still greater  rapidity, and as-
sumed a spiral form.  In these interest-
ing experiments we can not but admire
the ingenuity  of Hunter in selecting
the cock's comb  as the tissue
Avith  Avhich to  experiment, for
its highly  arterial  character
afforded greater opportunity
of success than any other tis-
sue that could  have been cho-
sen.                                                    &
  The epidermis, or external
skin, is- merely for the purpose
of protection; and we find
that in those parts which are
subjected, to continued press-
ure it becomes thickened, so as to fulfill the purpose for which
it is employed.
  An excellent  illustration of this fact is afforded in fevers,
Avhen the patient has been confined to his bed for a considera-
ble period, and the epidermis is  cast off from the soles of the
feet, leaAung them covered Avith a skin as delicate as that of a
new-born child, and so  sensitive that the first attempts to stand
or walk during convalescence are productive of severe pain.
Describe the epidermis. AVhat determines its thickness ? 
102              APPENDAGES OF THE SKIN.
Skin of Palm magnified 20 Diameters.
Fig. 91.
        Fig. 90.           A very good illustration of the thick-
                     ening of the skin from pressure is the
                     hard callous, called a corn, which is usu-
                     ally formed on the upper surface of the
                     toes, but which is  sometimes produced
                     between them.   The latter variety is ex-
                     ceedingly painful.
                       The layer of epidermis in contact with
                     the cutis  vera is composed  in part of
                     cells, which  contain  a  considerable
                     amount of coloring matter in the  dark
                     races.   When this is removed the  cutis
                     vera presents a pink appearance, due to
                     the great number of capillaries it  con-
                     tains.
                        The nails  are produced from the cut-
icle, and are horny growths which originate in a fold of that
                    membrane.   The rate of increase  varies
                    with the  perfection of nutrition, and it is
                    said that the thumb  nail can  be  repro-
                    duced in  four  months, but the time seems
                    to be overestimated.
                      The hair follicles also originate in a fold
                    of  epidermis, which assumes  a tube-like
                    form,  and produces a depression in the
                    derma.  Each hair takes its  origin from
                    the bottom of its own  follicle, and may be
                    considered as being composed of two parts,
                    an internal or medullary portion, with an
                    external  epithelial  covering, formed of
                    pavement cells, which overlap each other
                    like the scales of a fish.   It is this pecul-
                    iarity which enables  us to cut a single
                    hair Avith a sharp knife when it is held by
                    one extremity, the edge of the instrument
passing with comparative ease between the exposed scale-like
margins of the cells when applied in that manner, but gliding
over them,  and failing to cut the hair, Avhen it is  held by the
other extremity.
   The ducts of the glands of the skin pass through the cuticle
but do not  appertain to it.  The papillae also, though they pro-
Section of Human Hair.
 How are corns formed ? In what part of the skin is the coloring matter of the dark races
deposited ?  Describe the nails.  How is hair produced ? 
THE  GLANDS OF THE SKIN.
103
Fig. 92.
Section of r-'kin magnified 10
     Diameters.
Fig. 93.
ject into the  cuticle or epidermis, can not be regarded as be-
longing specially to it.
  The cutis vera, true  skin, or derma, is composed of fibrous
tissue, Avhich  connects it with the under-
lying tissues, and holds in  position the
blood-vessels, glands, nerves, involuntary
muscle cells,  and the  other parts which
aid in its construction.
  In Fig.  92, a is the derma; b, rete mu-
cosuni;  c, epidermis;  d,  sudoriparous
glands; e, their ducts; /, their apertures;
g, hair sacs; h, sebaceous glands; i, depos-
its  of fat.
  The  sebaceous or ceruminous  glands
are found in  the skin of all parts of the
body, and usually in  connection with the
hair follicles.  It is their  office to lubri-
cate the skin, and keep it soft and flexible; they also furnish
the hair with the oily material necessary to give it
a glossy look and keep it soft.  The secretion of
these glands  is almost entirely the product of cell
action.
   The sudoriparous glands are composed of a tube,
Avhich, commencing in the skin, passes to the low-
est stratum of the derma, or  even to the tissues
beneath, Avhere it forms a coil, among the meshes
of which blood capillaries  pass in  every direction.
r$ie coil and its capillaries form a small gland, the
tubular portion of which  is lined with pavement
epithelium throughout its whole course.
   The secretion of the sudoriparous glands is com-
posed entirely of Avater and salts, and substances
soluble  in water;  it is free from the extractive
which exists in  the secretion of other glands, and
affords an interesting confirmation of the fact that
spheroidal cells produce that constituent, the su-
doriparous fluid lacking- the extractive or fatty
bodies, because  the gland does not contain the peculiar cells
which are necessary for the  separation of such substances from
the blood.
Sudoriparous Gland
 magnified 20 Di-
 ameters.
  Describe the cutis vera. AVhat is the function of the sebaceous glands, and where are
they found?  Describe the sudoriparous glands, their position and function.  How do they
act? What is the construction of the sudoriparous fluid? 
104         ACTION  OF THE GLANDS OF THE SKIN.

  The study of the glandular system of the skin presents some
points of considerable interest;  among these, the separation of
the mere filtering mechanism, represented by the sudoriparous
glands, from the proper secreting spheroidal cell of the seba-
ceous glands, is perhaps the most interesting, since it gives us
the clew to the explanation of the action of the kidney and oth-
er organs.
  The sudoriparous glands not only excrete substances from
the blood, but they also absorb fluids which are brought in
contact with the skin, as is demonstrated by the fact that if a
thirsty person bathes himself in fresh water, his thirst quickly
vanishes; and if the body is weighed before and after the bath,
it will be found to have gained in weight, owing to the absorp-
tion  of fluid by these glands.
  By virtue of this property, various nutritive substances, as
soups  and  stimulants, may  be introduced into the  system
through  the skin.  Many  medicines will also produce their
special action if they are applied to the skin, as well or even
better than when they are introduced into the system by the
digestive canal; among these  we may mention the prepara-
tions of mercury and belladonna, which have been used in this
manner for many years.
                     LECTUEE XXI.

                  INSENSIBLE PERSPIRATION.

Methods for determining its Quantity.—Diurnal and nocturnal Loss com-
  pared.—The Effect of Exercise.—The Substances produced by the Disin-
  tegration of Muscle when in Action escape by the Skin, and not by the
  Kidneys.—Relation of sensible and insensible Loss to each other.—Ef-
  fect of Ingestion of Food on insensible Loss.—Diurnal Variation in the
  Weight of the Body.

  The amount of material excreted by the  skin in the form of
insensible perspiration is far greater than is generally supposed,
as is demonstrated in the folloAving paper, read by me before
the New York Academy  of Medicine, May  24th, 1864:
  During two years' service as physician in the New York
and Bellevue  Hospitals, I Avas frequently impressed with the
importance of the skin as one of the great sewers  of the body,

  How is the secretion of the sebaceous  glands prepared? How is it proved that the sudo-
riparous glands absorb as well as excrete ? Can mercurial preparations be introduced into
the system by any other channel than the digestive canal ? 
         EXPERIMENTS ON  INSENSIBLE  PERSPIRATION.      105

and I determined that, when opportunity offered, its duties and
functions should be made the subject of study and experiment.
  To carry out, this intention, in the fall and winter of 1862 I
constructed a balance by Avhich the Aveight of the body of an
adult could from time to time be accurately determined, and
the variations duly noted.   Considering the size of the instru-
ment, it was very sensitive, for, when loaded Avith 200 pounds,
the addition of one grain to the contents of either pan was in-
stantly shown by a corresponding movement of the index.   In-
deed, the first difficulty Avith Avhich I had to contend was the
delicacy of the balance, for when  it Avas adjusted to produce
the result given above, it Avas  impossible to use it with satis-
faction ; for the movement of the  index  was so  sIoav, and the
diminution in the weight  of the  body due  to the insensible
perspiration so rapid, that it Avas out of my poAver to arrive at
a correct result.   This was, however, remedied by reducing the
sensitiveness in order to  adapt  the instrument to the work for
which it was intended.
  As regards the construction of the balance, it is  sufficient to
state that the beam Avas about six feet in length and two feet
six inches wide at the middle, tapering gradually to the ends.
It Avas supported at its centre on a frame-work, which raised it
six  feet above the floor.  To  one of the extremities of the
beam a pan  or platform was attached, on which the weights
were placed,  and to the  other a species of chair, in which the
subject of the experiment could sit in a perfectly natural, easy
position, as long as was necessary.
  The beam  and supporting frame-work were constructed of
pine wood two inches thick, that  they might be as light and
strong as  possible.   The knife-edges at the extremities of the
beam, on  which the  pan and  chair were  supported, and the
axis  or fulcrum at the centre, were made of the best hard-tem-
pered steel, accurately ground to give in section an equilateral
triangle measuring one inch on each side.  The centre axis or
edge was six inches long; those at the extremities, five inches.
The  centre axis rested on a perfectly flat plate of hard, polished
steel, while the  pans were connected  with the edges at the
ends of the beam by means of the usual stirrup-shaped  suspen-
sion  pieces.  In order to avoid any accident from slipping, a
groove on  a radius of one  quarter of an inch was cut  in the
toot-piece of the stirrup,  and carefully  ground to fit the knife-
edge on which it was to be supported.
  The weights employed were French; but if it is desired, the 
106      EXPERIMENTS ON INSENSIBLE PERSPIRATION.

results can be readily converted into our Troy standard—1000
grammes being equal to 2*679 lbs. Troy.
  Complications arising from variations in dress were avoided
by wearing in all the experiments the same clothes, the weight
of which was known, and of which I shall in future speak as
the weighing-dress.  Errors arising from variations in the time
of passing the sensible evacuations were also carefully avoided.
The method  employed in weighing was to place on the plat-
form a counterpoise heavier than the person to be Aveighed.
Equilibrium  Avas then obtained by taking small weights into
the hands while sitting in the opposite pan or chair of the bal-
ance ; adding this to the weight of the dress employed, and
subtracting the sum from that of the counterpoise, the Aveight
of the body at the time of the experiment was obtained.  Any
necessity for  the presence of an assistant to  watch the move-
ment of the index was obviated by attaching to the frame of
the balance  a small  silver reflector, in which the index scale
could be seen by the person sitting in the chair.
  A suitable balance being thus  provided, I  proceeded to the
inArestigation of various problems connected with the weight of
the body; the first that is presented is the consideration of the

   Diurnal and Nocturnal Loss by Insensible Perspiration.
  In order to determine the relation existing between the diur-
nal and nocturnal losses by insensible perspiration  (under
Avhich' title I have included all the  insensible  evacuations of
the body, not only those by the skin, but also  those from the
lungs), a series  of  experiments  was  made, which  extended
throughout the month of January, 1863.  The average of the
results obtained is shown in the following table:
Insensible Loss per Minute.	Temperature.	Dew Point.
Night Sleep........ -47 "	55° 50°	46° 42°
  In the above the nocturnal loss is that which takes place
during quiet, placid sleep, and the diurnal that which occurs
Avhen the body is kept in as perfect a state of rest as is  con-
sistent Avith comfort, most of the  time being spent either in
writing in the sitting or reading in the incumbent posture.
  To the observant, intelligent  physician, Avho has for many
years endeavored to control the condition of his patients by
seeking to give them sleep as' Avell as mere muscular rest, the
AAThat is the diurnal and nocturnal loss by insensible perspiration ? 
         EXPERIMENTS ON INSENSIBLE PERSPIRATION.      107

above  results give  the  explanation of the  Avonderful effect
which  sleep has, not only in restoring the tone of the nervous
system, but also in arresting the great loss of weight and the
emaciation Avhich attends so many diseases during the restless,
sleepless period, but which ceases  almost the moment that a
calm night, in Avhich sound sleep has been obtained, is granted
to the  sufferer.
   For  during such a night the insensible loss AAThich is contin-
ually taking place is only about one half of that which occurs
during simple muscular  rest without  sleep.   A sound sleep
usually marks the commencement of the stage of convalescence
in any disease.
   Having  obtained in these experiments the average loss per
minute by insensible perspiration during the day Avhile in a
state of rest, we shall regard it as the normal  diurnal standard
of loss, and proceed to examine the variations Avhich muscular
action  produces.
   To determine this, a number of trials were made, Avhich dem-
onstrate that in health, increased activity in these organs is the
chief cause of increase in the rate of loss by insensible perspi-
ration; and that in moving the body of an adult  weighing
65,000 grammes one mile, 44 grammes in addition to the usual
amount are lost by insensible perspiration.
   The data from which the aboAre  conclusions were  deduced
were obtained by performing a series of experiments in which
exercise, varying in duration and intensity, Avas undergone; and
determining the increase in the rate of insensible loss, it was
found to be forty-four thousandths of a gramme for every thou-
sandth of a mile per minute of motion, as is illustrated by the
following examples:
For 10-thousandths mile per minute motion, 1*16 gramme per minute of insensible loss.
 " 19    "     "   '•    "    "   1-67    "    "   "   "   "    "
 u 22    "     "   "    "    "   L88    "    "   "   "   "    "
 " 41    "     "   ;'    "    "   2-40    "    "   "   "   "
   These examples not only bear out the statement regarding
the increase in loss Avhich folloAvs active muscular exertion, but
they also sIioav how great an influence muscular action has in
promoting  the function of insensible perspiration; a movement
of forty-one thousandths of a mile per minute, which is equiv-
alent to three miles an hour,  causing the rate of loss to rise
from 80 to 240.   Could we have indicated to us more clearly
the true channel through Avhich the products of Avaste and de-
What is the effect of motion on the insensible perspiration?
4 
108      EXPERIMENTS ON INSENSIBLE PERSPIRATION.

cay in the interior of the economy during violent muscular ac-
tion are thrown off?
  In  all our works on physiology, it is the received doctrine
that the urea of the urine represents the results of the disinte-
gration of the muscular, or chief nitrogenized tissue of the body.
It follows, of course, that the proportion of this ingredient of
the urine should increase greatly whenever the amount of mus-
cular  action is increased.
  In my inaugural thesis for the degree of M.D., published in
1856  (see Lecture XXVIL), the experimental examination of
this question was fully entered on, and by the use of new and
more  reliable  methods for the determination  of urea, it was
demonstrated that  exercise does not influence the proportion
of this substance contained in the urine in the manner usually
supposed, as Avill be seen in the following table:
For 24 Hours.	Urine.	Solid Residue.	Urea.	1000 Solid Residue contain of Urea
Average Loss...	1106-905-	55-584 52-031	27-213 25-472	490-489-
				
  The diurnal amount of motion in the results given under the
head of average loss was about four miles a day;  that under
the title of exercise was thirteen miles a day.  If it  is true that
urea is the result  of disintegration of muscular tissue, we are
justified in expecting to  find a  very  great increase in  the
amount of that substance when long-continued exercise is un-   *
dergone; but, on the contrary, not only is the quantity of urea
and the amount of urine and solid residue diminished, but the
proportion of nitrogenized matter contained in the solid residue
also undergoes diminution, thereby  showing in  the most con-
clusive manner that the products arising during the disinte-
gration of muscular tissue do not find their way out of the sys-
tem in the urinary secretion.
  The experiments of Lehmann on the  influence of variations
in diet, and the consideration of the relations of the diurnal
and nocturnal urine to each  other, furnish additional  support
to this opinion.   Hammond  also has  shown that increased
mental exertion is invariably accompanied by increased elimi-
nation of urea, demonstrating, as he  supposes, the effect of the
nervous system  on the production of urea.  But we may ex-
plain the increase by the fact  that during mental exertion the
body is kept in a comparative state of rest, in which condition

  What is urea generally supposed to represent?  Is this doctrine supported by experiment ?
Does diet influence the formation of urea? 
         EXPERIMENTS ON  INSENSIBLE PERSPIRATION.      109

I have shoAvn  that there is  more urea  excreted than  during
violent exercise.
  Keeping in view the facts regarding the diminution of the
nitrogenized  ingredients in urine during violent muscular ac-
tion, we haAre in part the explanation of the great increase in
the loss by insensible perspiration under  such circumstances.
Nor is there any thing  surprising in the  statement that the
products arising  during  the  disintegration of  muscular tissue
escape as insensible perspiration rather than by the kidneys,
for  Ave can not imagine any channel through  which it could
take place more rapidly or in a more effective manner.
  In support of the opinion  that the effete substances  arising
during the destruction of muscular tissue escape by the skin or
lungs rather than by the  kidneys, let any one appeal to his
own experience.   We all have  frequently, at  A^arious periods
of our lives,  undergone  great muscular  exertion, AA^alked. per-
haps fifteen or twenty miles without resting for more  than  a
few minutes, and passed but very little  urine  by the Avay, or
eA^en none at all; the journey  ended, there  was no  great in-
crease in the  quantity of urine, and yet our reason tells us that
there must have been a great destruction of muscle in order to
move a Aveight of 120 to 200 pounds over a distance of many
miles;  and we are obliged to admit that there could not  be a
more suitable and perfect channel for the removal of the prod-
ucts of muscular Avaste  than that of insensible perspiration,
either by the skin or the lungs, nor a more favorable condition
than the vaporous or gaseous state.
  It may also be demanded how we can  explain the great con-
gestion of the  skin which almost immediately supervenes on
exercise, except by supposing that effete materials are being
rapidly voided; and increased congestion is necessary, in order
to produce increased activity in any organ.  The  mere state-
ment that the great flow of blood to the skin  is only for the
purpose of reducing the  temperature by evaporation  is not al-
together satisfactory.
  Organic tissues decaying or burning, oxidizing slowly or rap-
idly, disappear  in the form of gases or vapors, as carbonic  acid,
ammonia, and nitrogen.  In  animals we know that carbonic
acid is given off, and the presence of ammonia, nitrogen, and
other inorganic and  organic  compounds  as constituents of the
secretions both of the skin and lungs has been demonstrated
  What facts support the theory that the  loss  by muscular action is through  the skin, and
not by the kidneys ? 
110      EXPERIMENTS ON INSENSIBLE PERSPIRATION.

by Berzelius and other chemists.   The organic compounds are
especially to be noticed as causing the death-like, sickly odor
which pervades the closed wards of a hospital, or which exists
in the apparatus in which experiments on respiration have been
conducted.
  The consideration of these facts affords sufficient justification
for advancing the opinion that the products of the disintegra-
tion  of muscular tissue find their way out  of the  system, not
through the urinary  apparatus, but as insensible perspiration
from  the lungs and skin;  and the great increase in the insen-
sible  losses  caused by violent  exercise is in great part due to
the evacuation of the  products of muscular waste through those
channels.
  While we are  considering the evacuation of effete material
in a form Avhich is not appreciated by the senses, it becomes a
matter of interest to determine whether the  loss due to muscu-
lar action ceases as soon as the exercise ceases, or is continued
for some time afterward.   In order to answer this inquiry, I
made a series of experiments in the months of February and
July, 1863.   The rate of loss before exercise was first determ-
ined.   I then walked on  different occasions distances varying
from  one to five miles, and by Aveighing as soon as I returned,
obtained the loss during the exercise.   I then weighed at inter-
vals  of tAventy minutes, so as to  find at Avhat time the rate of
loss became the same as before the exercise was undertaken.
  The results obtained shoAved that the rate of loss is increased
for some time after exercise, and it is necessary that about an
hour  should elapse before the standard is regained; as illustra-
tions, a couple of experiments are given.  The average rate of
loss per minute in the state of rest was '79 grammes.
                  Rate of loss per minute after violent exercise.
No. I. First (20 minutes), 1-25. Second (20 minutes), -91.  Third (20 minutes), -76
        grammes.
No. II.  First (20 minutes), 1G5. Second  (20 minutes), 1-00.  Third (20 minutes), -90
        grammes.
  Both of these experiments show a steady decrease in the rate
of loss after the exercise  ceased.  In the first, at the close of
one hour, the insensible loss had  not only reached, but had even
fallen below the normal standard, *79; while in the second, in
which the loss was greater, it had not quite reached the stand-
ard.   From the variations in the amount of insensible perspira-
tion caused by exercise, Ave now  pass to the consideration  of
Docs the increased loss caused by muscular action cease as soon as exercise ceases ? 
         EXPERIMENTS ON INSENSIBLE PERSPIRATION.      Ill

The Relations of the Insensible and Sensible Losses to each
                        Other.
  Among those who have devoted time and study to this sub-
ject, no one is more worthy of mention than Sanctorio.   In his
work "Medicina  Statica," published in 1720, the reader will
find many  facts which would be considered ornaments to the
pages of any of our modern scientific journals ; and though he
had to contend Avith  numerous difficulties, and his writings
bear the impress  of the times  in which he liATed, yet his work
was a grand step in the right direction, for he  made the  at-
tempt to bring the great questions of physiology to the test of
the balance, and force from nature truthful but  unwilling an-
swers.
  From the Aphorisms of Sanctorio Ave extract the following,
in order to demonstrate how  highly he esteemed the subject
with Avhich Ave are dealing.

                       "Aphorism 2.
  " If a physician who has the care of another's health is  ac-
quainted only with the sensible supplies and evacuations, and
knows nothing of the waste that is daily incurred by insensible
perspiration, he will only deceive  his patient, and never cure
him."
  In order to enforce the truth and importance of the above, he
gives the results of his experiments, obtained by the balance:

                       "Aphorism 6.
  " If eight pounds of meat and drink are taken in one day,
the quantity that usually goes off by insensible perspiration in
that time is five pounds."
  In evidence of the close and earnest manner in Avhich Sanc-
torio examined the various phenomena connected Avith our sub
ject, I quote the folioAving:

                      "Aphorism 56.
  " The body does not perspire at all times alike;  for in the
first five hours after eating there  wastes  about  a pound, the
next seven hours  about three pounds, and from the tAvelfth to
the sixteenth (at which time there  will be need of a fresh sup-
ply) nearly half a pound."

                      "Aphorism 65.
  " Even those men AAmo are in a  perfect state of health, and 
112      EXPERIMENTS ON INSENSIBLE PERSPIRATION.

observe the utmost moderation in living, once in a month in-
crease beyond their usual  weight to the quantity of one or two
pounds, and  at the month's end return again to their usual
standard, in the same manner as women do, but then by a crit-
ical discharge of urine, it being either increased in its quantity
or more turbid."

  The above bear the impress of the mind that  originated
them; and though Sanctorio has in his book added many other
aphorisms which  Ave now know must have been purely ideal,
still  these and many others, which we have neither time  nor
space to quote, give evidence of deep thought; and when we
take into consideration the times in which he wrote, Ave can al-
most forget the mixture of ideal fancies with  experimental re-
sults.
  Passing to the consideration of the relations of the insensible
to the sensible losses, and taking the period of sleep as present-
ing conditions which are free from external influences, we find
that the insensible loss by the lungs and skin is greater than
the sensible loss by the kidneys, as is shown  in the folloAving
table:
      Insensible loss per minute, -47 gramme.  Temp., 50°.  Dew Point, 42°.
      Sensible   "  "   "  -40   "      "   "    "   "  "
  Not only is the insensible loss greater than the sensible by
the  kidneys during the  night, but  the same relation  exists
throughout  the twenty-four hours, as we shall find if we com-
pare together the total diurnal amount of these excretions.
  Before giving the results of my oAvn experiments on this sub-
ject, I shall recapitulate briefly what has been done by others
who have made these excretions a subject of study.
  Sanctorio, as we have just seen, states that  if the  ingesta in
one  day amount to eight  lbs., no less than five lbs. find their
way out of the system in the form of insensible perspiration.
  Seguin made the attempt to  determine the loss through the
skin by inclosing himself in an  air-tight bag, and ascertaining
the rate of loss Avith the bag and Avithout it, the difference rep-
resenting the loss through the skin, which he found Avas 2'75
pounds per diem.  He  also found that the loss by the lungs
being 7, that by the skin was 11.
  Valentin obtained, as the result of his experiments, a loss of
2*35 pounds per diem by the skin.
  What was the result of the experiments of Seguin ?  How were they performed? AA7hat
were the results obtained by Valentin ? 
          EXPERIMENTS ON INSENSIBLE PERSPIRATION.      113

   Many objections may be urged against experiments perform-
 ed in the manner in which those  of Seguin Avere conducted
 Inclosing the body in an air-tight membrane interferes  seri-
 ously with the functions of the skin, and the results  obtained
 by experiments, conducted under conditions Avhich alter or in-
 terfere Avith the normal state of the body, are not to be relied
 on unless they are sustained by others Avhich give similar re-
 sults, and against which  such objections can not be advanced.
 Seguin, inclosed in his air-tight bag, must really  have  obtained
 results  which represented the body while in a vapor-bath  at
 over 90° Fah., which is not by any means its normal condition.
 And not only was the temperature  and state of moisture of the
 air changed, but the escape of the various excreta interfered
 with, and consequently the rate of loss changed from the nor-
 mal standard.
   In my experiments, all such sources of error have been care-
 fully avoided;  the body has always been in the normal condi-
 tion — during the  day employed in the usual  avocations,  at
 night at rest in bed.
   In the spring of 1856 I made several experiments on my
 own person, in order to  determine  the  loss by insensible per-
 spiration through the respiratory apparatus.  I have thought
 that it would add to the interest of this portion  of our subject
 if they  were  grouped with those on perspiration through the
 skin and the  sensible evacuations, viz., faeces and urine, and
 compared with the ingesta, Avhich have also been subjected  to
 examination.  Carrying out this idea, Ave will first recapitulate
 the results of the experiments on respiration, and then pass  to
 the consideration of the amount of liquid  and solid food intro-
 duced into the system each day.
   The average of many experiments showed that the number
 of respirations per minute being 16, and the dew point of the
 breath 94°, the volume of each respiration was 38*8 cubic inch-
 es, and the diurnal insensible loss  through this channel 464
 grammes.  These  results  were  published in the New York
 Medical Times for July, 1856.
   The loss by the skin was obtained by deducting the loss by
 the lungs (464 grammes), given above, from the total loss l>y
 insensible perspiration, 1108, which gave  as  loss by the skin
alone 644 grammes.
  The loss by urine for my own person  I determined, and pub-
lished in  my thesis many years previously. A few experi-
              AVhat were the results obtained by this plan ?
                            H 
114      EXPERIMENTS  ON INSENSIBLE PERSPIRATION.

ments wTere  made, in order to find Avhether it had undergone
any change; as it was materially the same as then obtained, I
discontinued my experiments and adopted the  old standard,
which was 1106 grammes per diem.
  The amount of feces passed was also determined by Aveigh-
ing before and after the  discharge.   The average per  diem
quantity was found to be 159 grammes.
  In the experiments made on the ingesta, care Avas taken not
to eat or drink any thing except at the regular meals.  Then,
by weighing before  and after eating, and  making due allow-
ance for the  insensible loss during each meal, the quantity con
sumed was accurately determined.
  The average of results, extending over a period of more than
a month,gave the folloAving quantities : Breakfast, 386; Lunch,
380; Dinner, 1231; Tea, 376. Total per diem, 2373 grammes.
  Collecting these results together, we obtain the following ta-
ble, which shows at a glance the diurnal amount  of sensible in-
gesta, and the manner in which the food and water are finally
disposed of by the system.
Ingesta.	Egesta by
	Lungs............ 464 J 1108. Urine............ 1106
Lunch................ 380 Dinner............... 1231 Tea................... 376	
	2373 grammes.
2373 grammes.	
  Converting the above  into Troy pounds, we find that the
diurnal amount of food and liquor taken is about 6*36 pounds,
of which 2'97 pounds are lost through the skin and lungs, and
constitute the insensible perspiration of Sanctorio.  It will be
remembered that the statement he made was, that out of eight
pounds of food and liquid taken into the system, five  pounds
pass off as insensible loss.  Though the above results do not
confirm his figures, they support and bring prominently forward
the great importance of the losses through this channel, and the
necessity of devoting more attention to the study, not  only of
the amount, but also of the composition of the insensible losses,
before  we can clearly comprehend the physiological operations
and pathological changes in the human system.
  In the following table the results of my experiments are
compared with those of others Avho have made the excretions
of the body the subject of examination and study:
Compare the sensible with the insensible loss.  ' 
EXPERIMENTS ON  INSENSIBLE PERSPIRATION.      115
Ingesta.	Loss by Skin. Lung3.		Total Insensible Loss.
Sanctorio............ 8 lbs.	2-75 lbs. 2-35 " 2-15 " 1-72 "	1-75 lbs. 1-25 "	5 lbs. 4-50 lbs. 2-97 "
			
Draper............... 636 lbs.			
   On submitting the above to examination, it will be found
 that my results  agree with those  of Seguin in confirming the
 statement that the loss by the skin is greater than that by the
 lungs, though the proportion was not so much in favor of the
 skin as it  was in his experiments.  The difference is probably
 due to the manner in which his results were obtained, viz., by
 the  use, as before stated, of an air-tight bag, Avhich must have
 stimulated the action of the skin by cutting off the loss of heat
 through evaporation, and so, by congestion, elevating the  tem-
 perature of the body, and thereby increasing the insensible loss,
 just as when we take a vapor-bath the loss is greatly increased,
 and perspiration in the  sensible form of sweat literally pours
 off the body.

     Effect of Ingestion of Food on Insensible Perspiration.
   In the examination of this subject, we shall first take up the
 consideration of the effect on the nocturnal loss of taking food in
 larger quantities and later in the evening than is customary, and
 then shoAV the difference in rate of loss before and after meals.
   Variation in  the regular time of taking the last  meal, or
 change in  the character of the food, impresses a change on the
 nocturnal loss, as is demonstrated by the fact that on one occa-
 sion, after  a late  hearty dinner, it rose to "77 gramme  per min-
 ute,  and in tAvo other instances, when a light supper was taken,
 to "55, the average being "47.  From this we conclude that the
 ingestion of food  causes an increase in the rate of insensible  loss.
   If we  examine the rate of loss before and after a meal, the
 body being kept in a state  of rest, we obtain evidence in  sup-
 port of the above statement.   During the month of January,
 my experiments were so arranged as to give the rate of loss in
 a state of rest before and after dinner.   The averages of the
 results obtained show a difference of -02 gramme; the rate be-
 fore  dinner being *79, Avhile that after dinner Avas "81.
  With Sanctorio, I therefore agree that the taking  of food in-
fluences the rate  of loss by insensible  perspiration, but the in-
crease in loss after a meal,  as  obtained in  my experiments, is
far less than that obtained by him.
AVhat is the effect of ingestion of food on the rate of insensible perspiration? 
116      EXPERIMENTS ON INSENSIBLE PERSPIRATION.

Variations in the Weight of the Body from Day to Day during
                     extended Periods.
  Both Gall and Levy hold the opinion that in men there are
periodical manifestations  similar to those existing  in females,
which are scarcely visible in robust individuals, but are often
very evident in those of feeble constitutions, or in persons who
are suffering from fatigue following hardship.  Hammond also
states that he has noticed the same variations in many of his
friends, the  monthly manifestations being in the form of head-
ache, epistaxis, diarrhoea, etc.
  In order to arrive at a just conclusion regarding this portion
of our subject, I extended my observations on the weight of the
body over a period of three months, so as  to obtain sufficient
data from which some reliable statement could be deduced.
  The greatest care was taken to weigh as nearly as possible at
the  same hour  of the day in the different experiments.  The
time chosen was  half past  seven  A.M., that is, shortly after
rising in the morning.  All irregularity  regarding the evacua-
tions was scrupulously avoided.   The results are given in the
folloAving table, together  Avith the temperature and dew point.
The average weight for each month is also  stated.
April, 1863.
Date.	Weight	Tempera-	Dew	Date.	Weight	Tempera-	Dew
	in Grammes.	ture.	Point.		in Grammes.	ture.	Point.
18	64-155			24	63-710		
19	64-145			25	63-417		
20	63-520			26	63-790		
21	63-475			27	63-713		
22	63-693			28	63-615		
23	63-375			30	63-895		
Average Weight during April, 63-709 grammes.
May, 1863.
	Weight	Tempera-	Dew	Date.	Weight i	Tempera-	Dew
	in Grammes.	ture.	Point.		in Grammes.	ture.	Point.
1	64-885			18	65-345		
3	64-007			19	65-770		
4	64-505			20	65620		
5	65-060			21	64-420		
6	65-055			22	64-870	67	65
7	64-860			23	64-545	75	68
9	• 64-884			24	64-710	67	62
ao	65-200			25	64-520	62	56
n	65-520			26	64-550	60	56
12	65-070			28	65-020	64	60
13	65-300			29	64-920	70	65
14	65-285			30	64-960	73	70
15	65-220			31	64-880	73	70
17	65-320						
Average Temperature and Dew Point, 68°, 64°.
Average Weight during May, 64-975. . 
EXPERIMENTS  ON INSENSIBLE PERSPIRATION.      117
June, 1863.
Date.	Weight in Grammes.	Tempera-ture.	Dew Point.	Date.	Weight in Grammes.	Tempera-ture.	Dew Point.
1	64-600	71	67	16	64-160		
2	64-300	67	60	17	64-745		
3	64-920	66	60	18	64 900		
4	65 110	65	60	19	64-600		
5	65-190	64	58	20	64-550		
6	65-120	62	59	22	65 320		
7	64-990	63	57	23	65-320		
8	64-870	64	59	24	65-095	65	60
9	64-770	66	60	26	65-820	67	63
11	64-690	71	66	27	65-345	65	60
12	65-180	70	67	28	66-120	67	63
13	65-250	67	64	29	66-870	67	64
14	65-230	65	60	30	66-290	68	65
15	64-685	70	66				1
Average Temperature and Dew Point, 66°, 61°.
Average Weight during June, 65-112.
July, 1863.
Date.	Weight	Tempera-	Dew	Date.	Weight	Tempera-	Dew
	in Grammes.	ture.	Point.		in Grammes.	ture.	Point.
1	65-190	71	67	11	65-390	75	75
2	66-220	73	70	13	66-190	72	71
3	66-350	73	67	15	65-650	70	67
4	65-970	73	72	16	65-470	75	73
5	65-510	70	66	18	65-695	70	67
6	65-920	71	68	19	65-685		
7	66-320	71	67	21	65-205	72	70
8	65-345	75	72	22	65-520	67	65
9	65-250	74	70				
Average Temperature and Dew Point, 72°, 69°.
Average Weight during June, 65-755.
   From these  experiments, Ave find that though there is at
 times an increase in weight, and variations from day to day
 also exist, they do not appear to be reducible to any special or-
 der, or referable to any particular cause, but are irregular, and
 do not demonstrate the laAv which Sanctorio gives in his  65th
 Aphorism—that  in men  in perfect health there is a monthly
 increase in weight, and also a diminution marked by a critical
 discharge.  They do not even establish with complete satisfac-
 tion the extent to which changes in the dew  point affect the
 weight of the body.   The only fact that is satisfactorily shoAvn
 is, that during  the period of the experiments,  viz., from April
 18th to  July 22d, there  is  an increase  of Aveight each month,
 which is probably due  to  the decrease in physical exercise
 during the hot  Aveather.
  ReA7ieAving the results Ave have obtained, we  conclude:
  1st. That the effete  materials arising during the disintegra-
tion of muscular tissue are evacuated as  insensible perspiration,
Is there any loss in men similar to that in women represented by menstruation ? 
118
THE  RESPIRATORY APPARATUS.
and not as urea through the urinary apparatus, a definite time
being required after long-continued  exercise before the insensi-
ble losses regain the normal standard.
   2d. That the loss by the skin and lungs is greater than that
by the kidneys.
   3d. That Ave  can not establish the existence of a regular
monthly increase in weight, as supposed by Sanctorio and oth-
ers.
LECTURE  XXII.
RESPIRATION.
Divisions of the Respiratory Apparatus.—The Larynx.—The Trachea.—
  The Bronchi.— The Air-cells.—The Lungs.— The Divisions and Mem-
  branes of the Lungs.—Rate of Respiration.—Action of the  Lungs.—
  Stages of Inspiration.—Diffusion of Gases.—Influence  of Membranes
  on Diffusion.
  We have  seen in the preceding paper that nearly one half
of the insensible loss to  which the system  is  subject  occurs
through the channel  of the lungs; we therefore pass  to the
"consideration of the structure and functions of the respiratory
apparatus, which consists of the larynx, trachea, bronchi, and
capillary bronchi, Avhich, Avith the air-cells, form the lungs. ^
                               The  larynx  is  a  pyramidal-
                             shaped box, formed  of cartilage,
                             lined with mucous membrane.  It
                             contains the organism by which
                             the voice is produced, and lies in
                             front of the pharnyx, so  that the
                             food passes over the top  of the
                             larynx to reach the pharnyx, or
                             entrance to the digestiATe appara-
                             tus.   In order  to  prevent Avater
                             and  solid  food entering the  lar-
                             ynx, it is furnished Avith a valve,
i, called the  epiglottis, which closes the entrance to the air-pas-
sages during deglutition.
   The  trachea passes from the larynx to the cavity of the
chest.  It consists of a number of rings of cartilage, which are
Side View of Larynx.  Back View of Larynx.
  What is the relative loss by the skin and lungs compared with that by the kidneys ?
What are the divisions of the respiratory apparatus ?  Describe the larynx.  What is its po-
sition ?  How is food kept from dropping into it? Describe the trachea. 
             CAPILLARY BRONCHI AND AIR-CELLS.          119

connected by membrane, forming a tube with stiff walls, which
can resist the pressure of the muscles of the neck, and prevent
the. closure  of the  air-passages
during their action.
  Reaching the  thoracic  cavity,
the trachea divides into the right
and left bronchi, one passing to
each lung.  The  right  bronchus
is shorter, wider, and more hori-
zontal in its course than the left;
it is about one inch in length, and
divides, as it enters the lung, into
two branches.  The left bronchus
is about tAvo inches long; it di-
vides into  three branches,  and
forms nearly a straight line Avith
the trachea;  consequently, Avhen
foreign bodies fall into the respi-    Trache8i Bronchi) and Bronchial Tubea_
ratory tubes, they are more liable
to pass into the left than the right bronchus.
   Both the great bronchial tubes, like the trachea, consist of
rings of cartilage united by a membrane composed of elastic
and muscular fibres.  This form of construction is retained un-
til they reach the lungs, and subdivide into the branches which
pass into the lobes.
   The bronchi continue to subdivide after they reach the lungs,
until finally tubes of very fine  calibre are formed: these are
called capillary bronchi.  Each capillary bronchus terminates
in a cluster of air-cells, Avhich form a lobule.  The bases of the
lobules are marked by the network of lines which is visible on
the  exterior  of the  lung.                Fig.9r.
The cells of the same lobule
intercommunicate freely, but
the cells of different lobules
can  only communicate
through their respective ca-
pillary  bronchi.
   In Fit/.  97, a represents
the  natural size  of the sec-
tion of lun^ tissue Avhich is
magnified  9 diameters at 0,      Capillary Bronchi and Air-cells of a Lobule.
  Describe the bronchi.  AA7hat are their subdivisions ? What are the air-cells ?  What are
the lobules ?  Do the air-cells communicate ?
 
120
THE  ANATOMY  OF THE  LUNGS.
Capillary Blood-vessels of Air-cells.
                               to illustrate the air-cells, c. and
                               capillary bronchi, t.
                                 The air-cells A^ary in diameter
                               from -^-0- to ^o of an mch- They
                               are composed of a membranous
                               AArall, furnished with involuntary
                               muscle-cells, and lined  Avith mu-
                               cous membrane, which  is  pro-
                               vided Avith ciliated epithelium.
                               On the Avails of  the  cells,  and
                               between them, the capillary ves-
                               sels  of the  pulmonary  system
                               are distributed: they are about
3-0V0  of an inch in diameter, so  that the  blood discs can pass
through with comparative freedom.
                                           The lungs are com-
                                        posed of the bronchi,
                                        air-cells, and blood-ves-
                                        sels.  They are placed
                                        on  the   sides  of the
                                        thoracic  cavity,  the
                                        heart lying  between
                                        them.  They are near-
                                        ly  conical in   shape,
                                        and held in position
                                        by  the  roots,  Avhich
                                        are  attached to their
                                        inner  sides,  and  are
                                        formed  of the large
                                        bronchial tubes  and
                                        blood - vessels   which
                                        enter the organ.   The
                                        right lung is divided
        Relative Position of the Heart and Lungs.         info tTlT*PP lnV»P«!  atlfl
the left into two.  The liver encroaches on the right lung, ren-
dering it shorter than the left; but since  the heart lies chiefly
on the left side, the left lung is smaller than the right,  though
it is longer.                                         •
  The sides of the thoracic cavity which  contain these organs
are composed of the ribs  and intercostal muscles, Avhile the
  Describe the air-cells.  What is the diameter of the capillaries of the pulmonary artery ?
Describe the lungs.  What is their position ? Of what are the roots of the lungs composed?
How many lobes are there in the right lung—in the left? Which lung is the longest?
which is the largest ?
 
THE  STAGES OP RESPIRATION.
121
 floor is formed by the diaphragm.   A continuous serous mem-
 brane lines the thoracic Avails, and is reflected over the surface
 of the lungs: it is called the pleura.  The portion covering the
 Avails of the cavity is designated as the costal pleura;  that cov-
 ering the lungs is described as the pulmonary pleura.   The
 function  of this membrane is to give the organs contained in
 the chest perfect freedom of movement during inspiration and
 expiration.
   The capacity of the lungs is about 200 cubic inches, but this
 imparts a very faint  idea  of the amount of surface which the
 air-cells present for the arterialization of the blood.   The  num-
 ber of respirations is  about seventeen per minute, and in each
 inspiration seventeen  cubic inches are introduced, which hardly
 suffices to fill the large bronchi; consequently Ave must  seek
 for other forces in order to explain the final introduction of the
 air into the air-cells and blood.
   Respiration consists of tAvo distinct movements : 1st. Inqrira-
 tion, by which the fresh air is introduced; and, 2d. Fnpiration,
 by Avhich the foul air containing the  carbonic acid gas Avhich
 has been separated from the blood is voided.  The act of in-
 spiration may be divided into three distinct stages :
   1st. The 'mechanical stage, in which the pressure of the atmos-
 phere is called into play, and the air introduced into the large
 bronchi;  2d. Simple diffusion, by which the fresh  air  is intro-
 duced into the  bronchi, and passes  into the air-cells,  Avhile at
 the  same time foul gas passes outward; 3d. Diffusion through
 membranes and liquids, by which the oxygen introduced into
 the air-cells passes through their walls and those of the blood-
 A7essels to reach the plasma and  blood discs.
   In order to illustrate these movements, Ave call attention to
 certain physical phenomena, Avhich must be understood in or-
 der to give a rational explanation of the respiratory function.
   In Fig. 100, page 122, c c represents a jar, through the upper
 opening of Avhich a tube, a, passes, Avhich is  open aboA-e, but at-
 tached beloAV to a bladder,  b.  The jar may be regarded as rep-
 resenting the Avails of the thoracic cavity, the bladder the lung,
 and the open tube the trachea, affording a free  communication
 between the interior of the bladder or lung and the open air.
 Placing the apparatus in a larger vessel, d, filled with water, the
  What tissue composes the walls of the thoracic cavity? AAThat membrane lines the cavity?
 How is the portion that covers  the lung designated? AVhat is the capacity of the lungs?
 How many respirations in one minute ? How  many cubic inches in each ? What are in-
spiration and expiration ? AA'hat are the stages of inspiration ?  How may the first stage be
illustrated ? 
122                  SIMPLE  DIFFUSION.
Fig. 100.
                    lower opening of the jar is closed by the
                    fluid in the same manner  that the  dia-
                    phragm closes the lower part of the chest.
                    By alternately raising and depressing the
                    jar, we increase and diminish its capacity,
                    and cause the bladder to expand and con-
                    tract, imitating the analogous movements
                    of the  diaphragm, which, as it contracts
                    and relaxes, increases and diminishes the
                    capacity of the thorax, and causes the
                    lungs to collapse and expand.
                       As in  the preceding experiment the
                    bladder acts in a passive manner, submit-
                    ting itself to the effects of change in press-
                    ure, so the lung also acts passively, allow-
                    ing the air to flow in and out with the
                    movements of the diaphragm.  The tissue
                    composing the lung  consists in part of
                    elastic fibre, which assists to  a slight ex-
Mechanism of Respiratory Appara- tent  in emptying the organ of its  con-
                    tents, but, with this exception, the move-
ments are purely passive.
  The amount of compression and exhaustion exerted by the
action of the diaphragm is far less than is generally supposed,
being equal to about half an inch of water in each direction, or
        one inch total variation from the  extreme of ordinary
        inspiration  to  that  of expiration, as  may be  demon-
        strated  by breathing with the nostrils  open  through
        a tube of large bore, one end of which is  held loosely
        between the lips, and the other placed under the sur-
        face of water.
           The  second physical property  to which Ave shall
        draw attention is the  principle  of diffusion of gases.
        If a jar is filled with vapor of ammonia by moistening
        its sides with that  fluid, and placed mouth doAvnward
        over another jar Avhich has been  filled with vapor of
        hydrochloric acid in a similar manner, the light gas
        or  vapor in the upper jar passes  doAvnward into that
        contained in the lower jar, and, mingling Avith it, pro-
        duces a AAThite  cloud of sal ammoniac, which is equally
        diffused throughout both vessels.
Fig. 101.
1
Simple Diffu
   sion.
 Does the lung move actively or passively? What is the amount of pressure called into
action in inspiration? AVhat is simple diffusion of gases? How may it be illustrated? 
DIFFUSION THROUGH BARRIERS.
123
Fig. 102.
  To this phenomenon the name of diffusion of gases has been
given, and it is shoAvn by all gases that have been submitted
to experiment.   It is not produced by gravity, but takes place
against  it,  as  Avas  demonstrated in the  experiment  related
above, Avhere the light gas moved downward, and the heavy
one upward, in order to produce a uniform mixture.
  By virtue of this principle, the pure air Avhich was intro-
duced by the first or mechanical act is carried into the air-cells,
and the carbonic acid of the cells at the same  time
passes outAvard, to  mingle  with  the air  in the
bronchial tubes, and be ejected by the act of expi-
ration.   The introduction of fresh portions of oxy-
gen into the cells constitutes the second stage of in-
spiration.
  Not only Avill gases  mutually diffuse when  they
are freely exposed to each other, but the same effect
is produced with equal  or  eA7en  greater  facility
Avhen they are separated by a membrane.
  If the porous jar, a ct, in the figure, is filled Avith
air, and  then covered Avith a vessel, c c, containing
coal gas, the contents of the porous jar are  greatly
increased by the passage  of  the  gas through its
Avails, as is  shoAvn by the fluid in the glass  tube b,
attached to the jar, being depressed toAvard d.  If
the A'essel containing the gas is removed, the moATe-
ment  immediately ceases, and then commences  in
the opposite direction; the gaseous contents of the
jar diminish in volume, the fluid rising in the tube
to occupy the vacant space*
  Through  the walls  of poreless struc-
tures the same moArements of gases occur,
as may be demonstrated by taking a bot-
tle, a a, moistening  its  inner  Avails with
aqua  ammonia to fill it with the vapor
of that liquid, and then blowing a soap
bubble, c, in the  interior of the jar by
means of a tube, b, loosely fitted to its
mouth by  a cork.  If to the open pro-
jecting end of the tube we approach the
-tOppei' Of  the hydrochloric  acid bottle Diffusion through poreless Structures.

  How does gravity influence the diffusion of gases ?  How is the second stage accomplish-
ed?  AVhat is the influence of interposing membranes on the diffusion of gases? Explain
the experiment with the porous jar.  Explain the experiment with the soap-bubble.
Diffusion of Giise*
 through porous
 Barriers.
Fig 103.
 
124            DIFFUSION AGAINST RESISTANCE.
as soon as the mouth is removed, we find that a cloud of chlo-
  Fig. 104.  ride of ammonium is produced, showing that the amino-
        niacal gas contained in the bottle has passed through
        the Avails of the bubble to mingle Avith the gases from
        the lungs which it contained; and, reaching the open
        extremity of the tube, its presence  is indicated by the
        test employed.
           The  force Avith which  a  gas will penetrate such
        thick, strong, resisting membranes is perfectly irresist-
        ible.   The  experiment, Fig.  101, consists  in taking a
        stout tube  of glass, a b, through the bottom of which
        a  couple of platinum  wires, b c, pass, which can at
        pleasure be made to communicate with the poles of a
        Voltaic battery.   The tube is partially filled with wa-
        ter, e e, and a pressure-gauge, d, and suitable  stand or
        support introduced, on Avhich a slip of paper moisten-
        ed with nitrate of lead is placed.  The mouth of the
        apparatus is then closed with a stout piece  of India-
  ^Sins?  rubber, a a, and the platina wires are brought in con-
  pressure.  ^act yfah. ^he p0les 0f a Voltaic battery.  The passage
of the electric current causes the Avater to undergo decomposi-
tion, hydrogen and oxygen being evolved, Avhich, since their es-
cape  is prohibited by  the India-rubber, exert pressure, as is
shown by the rise  of the index fluid in the  pressure-gauge.
When a pressure of five or ten atmospheres is reached, the In-
dia-rubber is  covered by a jar containing  sulphureted hydro-
gen ;  the gas in an instant penetrates the membrane which sep-
arates it from the gases contained in the tube, to unite Avith
them, its passage and presence in the mixture of oxygen and
hydrogen being indicated by the blackening of the slip of pa-
per.  Increasing in  other trials the pressure in the tube, the
movement takes place with equal facility; we therefore con-
clude that pressure does not influence  the diffusion of a gas
through a membrane.
Can pressure influence diffusion through membranes ?  How may it be demonstrated ? 
COMPOSITION  OF' EXPIRED AIR.             12 J
                     LECTURE XXIII.
                   respiration— Continued.
Second and third Stages depend on Diffusion of Gases.—Stages of Expira-
  tion.— Difference between inspired and expired Air.—Experiments on
  Respiration.— Object of Respiration.—Diseases affecting the Respiratory
  System.

  The  experiments we have related furnish  us Avith  the  ex-
planation of the movement of the air from the air-cells to the
blood discs.  The tissues  or membranes through which it is
obliged to pass are exceedingly thin, being the delicate  wall of
the  air-cells, that of the blood capillary, and the  blood disc.
Through these the oxygen passes instantaneously, and, reaching
the  hsematin, is dissolved  by it, and changes  the color of the
disc from blue to red.
  At the same time, the carbonic acid, which  has been  held in
solution in the  plasma  by  the aid of phosphate of soda, is
surrendered to  the air-cell, and carried out of the system by a
movement  the  inverse of  that "which introduced the  oxygen
gas.
  If we alloAV atmospheric air to come in contact with lime-wa-
ter, it will, after the lapse of some hours, produce a pellicle of
carbonate of lime on the surface of the liquid; but if Ave pass
the  air from the  lungs through another portion of the  same
specimen  of lime-water, it immediately produces a copious pre-
cipitate, thereby demonstrating that the expired air contains a
far  greater  proportion of carbonic acid than  atmospheric air.
By careful chemical analysis it is found that air  contains only
one  part in two thousand of carbonic acid, while the expired
gases contain from three to four per cent.   With the increase
of the carbonic acid in the expired  air, there is also a diminu-
tion in the proportion of oxygen amounting to four or six per
cent.
  Some years since I made a series of experiments on the func-
tion of respiration, Avhich are of interest, as they deal Avith cer-
  Apply the principles of diffusion to the introduction of oxygen into the blood discs. What
are the stages of expiration?  AVhat is the difference between inspired and expired  air?
How may it be demonstrated ?  AVhat  is the proportion of carbonic acid in fresh atmospher-
ic air ? AVhat is the percentage in expired air ?  What is the loss of oxygen in expired air ? 
126            EXPERIMENTS on respiration.
        #
tain  points, such as the quantity of air introduced and the
amount of moisture  exhaled through this channel; they were
published in the New York Medical Times for July, 1856.  The
questions  Avliich that article discussed were,
  1st. What is the quantity of air exhaled in one minute ?
  2d. What is the influence of rapidity of respiration upon this
quantity ?
  3d. What is the amount  of water excreted by the lungs in
one minute ?
  4th. What is the influence of the  rapidity of respiratory
movement on  this quantity ?
  Many solutions have been giA^en of the above inquiries, from
the long-received assertion that there are seventeen respirations
in one minute, and seventeen cubic inches in each, to the recent
experiments ofVierordt, Avhich show that there are sixteen res-
pirations  in a  minute, and thirty and a half cubic inches in
each.  Nor is  it difficult to  account for the great discrepancies
which occur in these statements, when we consider the manner
in which some of the experiments were made; for example, in
determining the amount of air, one method was  by breathing
into a graduated gasometer, and displacing the water contain-
ed therein.  But when we  recollect that the normal disturb-
ance of pressure taking place during placid respiration is equal
to only one inch of water, we see how great an influence this
method of performing the experiment would have in falsifying
the results.
                      Another element of error was the dura-
                    tion of the experiments;  in some,  the
                    quantity contained in a  single expiration
                    being  determined, while in those of Vie-
                    rordt, which  are the best Ave have, the time
                    was only one minute.
                      In order to avoid these sources of error,
                    the apparatus Fig. 105 was resorted to.
                      The  air, as it escaped from the mouth,
                    was  conducted into a metallic vessel, kept
                    at 32° Fahrenheit by placing it in a  mix-
                    ture of ice  and Avater; here  its. moisture
                    was deposited, on account of the decreased
temperature.  A thermometer Avas placed in the tube which
 What are the objections to the methods formerly employed in determining the quantity of
air introduced in inspiration ? How may these be avoided ? 
EXPERIMENTS ON  RESPIRATION.
127
carried the air out of this condenser, as Ave may call it, and thus
the temperature of the escaping air was known.
1  It is evident that by the use of such an instrument all error
caused by the influence of pressure was avoided, for it required
no more effort to expel air through its cavity than it  does to
drive it through the trachea and the narroAv chink of the glot-
tis.  From the increased  weight of the condenser, the  amount
of water collected during an experiment was determined.
  Having obtained the Aveight  of Avater, and the temperature
of the air as it escaped from the condenser, it remained to de-
termine the dew point of the air as it escaped from the mouth,
Avhen, by means of the folloAving formula, the volume of air ex-
pired in a given time could be calculated: As the weight of
water in one cubic foot of air at the deAV point of the breath,
minus the weight of water in one cubic foot of air at the tem-
perature of that escaping from the condenser, is  to 1728 cubic
inches, so is the weight of water in the condenser to the  quan-
tity of air expired.
  In  order  to avoid the error of time, Avhich has entered into
the researches of other observers, each experiment was contin-
ued for the  space of twenty minutes, and from this the  amount
per minute  Avas calculated.   Having thus avoided the most im-
portant causes of error, Ave proceed to give the results  of some
observations made upon the aboAre principles; and, first,

         Of the amount of Air expired in one Minute.
                Number of respirations in one minute, 16.
                      Dew point of breath, 94°.
     Experiment 1........................................................... 619 cubic inches.
        "    2........................................................... 618  "
        "    3........................................................... 640  "
        "    4.......................................................... 615  "   "
             5........................................................... 621  "   "
     Average per minute................................................... 622  "    "
     Volume of each respiration..........................................  38.8 "   '■
  From this we find that when respiration was carried on at
its normal rate of sixteen movements in  a minute, the experi-
ment lasting for twenty minutes, 622 cubic inches were  exhaled
in one minute, and 38T8o  cubic inches constitute the volume of
each respiration, representing the physiological condition of the
function.  Let us now see the influence of decreased rapidity.
  In  order  to obtain a minimum, I breathed during the same
space of time as in the former experiments, but  at the rate of
only six movements in a minute, each act being as much retard-
  At the rate of sixteen respirations per minute, what is the amount introduced  at each in-
spiration by this method ? 
128
EXPERIMENTS ON  RESPIRATION.
ed as possible, thus seeking to obtain the smallest amount of
air which would satisfy the system during a someAAmat length-
ened period of time.   The results of the observations Avere as
folloAvs:
                 Number of respirations in one minute, 6.
     Experiment 1........................................................... 508 cubic inches.
             2........................................................... 486  "
        "    3........................................................... 541  "
     Average per minute.................................................... 511  "    "
  It still remained to determine the amount exhaled Avhen res-
piration is  hurried, and each act  as full as it is possible  to
make it under such circumstances, thus obtaining the greatest
volume of air that can be introduced into the lungs per minute,
the experiment being continued for twenty minutes.
  The result of one trial gaA^e the following:
                  Number of respirations per minute, 33.
     Experiment............................................................ 1077 cubic inches.

  From the foregoing results we obtain the following table:
No. of Respirations.                                         Cub. in. per min.
      6.     Least amount sufficing for wants of system.........................  511
     16.     Average demand..........................................................  622
     33.     Utmost extent of respiratory operation.............................. 1077
  From Avhich we conclude,
  1st. The  amount of air in  each  normal  respiration  is  38T80
cubic inches, the number of acts being sixteen per minute.
  2d. The  amount  of air introduced into the system depends,
for the  most part, on the  rapidity with which respiration is
carried on.

              Of the Water exhaled in one Minute.
  For the  solution of this problem the  same instrument was
used as in the experiments given  above, and  the method of
procedure was the  same.
  The results of four experiments were as follows:
                  Number of respirations in one minute, 16.
                       Dew point of breath, 94°.
     Experiment 1.  Grains of water per minute.................................... 4.378
         "    2.    "      "       " .................................... 4.539
         "    3.    "      "       " .................................... 4.329
         "    4.    "      "       " .................................... 4.418
     Average.................................................................................. 4.416

          Effect of decrease in Rapidity of Movement.
                  Number of respirations per minute, 6.
     Experiment 1.  Grains of water per minute.................................... 3.602
         "    2.    "       "       "  .................................... 3.415
         "    3.    "      "       " .................................... 3.743
     Average................................................................................ 3.586 
»  EXPERDIENTS ON  RESPIRATION.
129
                 Effect of increased Rapidity.
                  Number of respirations per minute, 33.
     Experiment.  Grains per minute................................................. 7.560

   Tabulating these experiments, we obtain:
     No. of respirations,  6. Grains of water per minute......................... 3.58G
                  16.   "      "      "  ......................... 4.416
              "   33.   "-     "      "  ......................... 7.560
   From this we find that the quantity of Avater  exhaled also
 depends on the rapidity of the respiratory act.
   These experiments were all continued for the same period,
 viz., twenty minutes.  They were all made at a temperature of
 56°, and a dew point of 49°.   The same person was the subject
 of each experiment, being a healthy adult weighing 130 lbs.;
 and the results may be summed  up in the  following  general
 conclusions:
   1st. The number of expiratory acts being sixteen per  minute,
 each contains 38-& cubic inches of air.
   2d. The amount of water exhaled in one minute at a  temper-
 ature of 56°, and a dew point of 49°, is 4T40\)60 grains.
   3d. The amount of water and air exhaled from the lungs is
 for the most part dependent on the rapidity of the respiratory
 act, increasing  and diminishing therewith.
   From the facts we have  given regarding  respiration, the
 reader will perceive that it  must perforin  some function of
 great importance to the system, for if the lungs cease to act but
 for a few moments, death is the result;  if we breathe a gas that
 is noxious, or air that contains but a very small proportion of
 carbonic acid, we die.
   Recalling the mechanism of the lungs, and the change im-
 pressed on the air while it remains in them, we can not avoid
 the inevitable  conclusion that the duty of these organs is to in-
 troduce oxygen into the system, and remove carbonic acid.
   In a previous lecture attention was drawn to the fact that
 many  animals not  only maintain a temperature  higher  than
that of the medium in which they live, but  they also  possess
the power of keeping it at a fixed degree.  This can only be
done by means of an oxidation in the system of carbon, hydro-
gen, and other substances, and it is the function of respiration
to introduce the necessary oxygen from the air.
  How does the rate of inspiration affect the quantity inspired ?  AVhat is the amount of
moisture given off by the lungs ?  AVhat is the influence of increased rapidity of respiration ?
What is the function of respiration ?  What facts may  be advanced to prove these state-
ments?
                             I 
130       DISEASES  OF THE RESPIRATORY APPARELS.

   Other gases, with the exception of protoxide of nitrogen, will
not answer, and even the protoxide  can  only be  used for a
short time.  We may, it is true, for a few moments employ hy-
drogen or nitrogen, but they finally cause death by acting -in a
passive manner, and preventing the entrance  of oxygen.   Car-
bonic acid, and the great majority of gases, are not only incapa-
ble of supporting respiration, but also possess  a directly poison-
ous effect.
   Carbonic acid being one of the products of the action of oxy-
gen on the tissues of the system, is,  as we have stated, very
poisonous, and must therefore be removed as fast as it is pro-
duced.  This the lungs accomplish by the act  of expiration, the
carbonic acid being held in solution by the plasma of the blood,
and so conveyed to the lungs as quickly as possible.
   Before closing the consideration of the respiratory organs, it
is necessary to make a few remarks regarding the diseases
Avhich affect them, since in our city a very large proportion of
the mortality  is caused by the diseases of the lungs and their
appendages.
   1st. Croup is an  inflammation of the mucous membrane of
the larynx and upper parts  of the respiratory tract, attended
by the exudation of lymph and formation of a false membrane,
which gradually or suddenly closes the air-tubes, and so causes
death; it  sometimes extends down into the capillary bronchi.
   2d. Bronchitis is an ordinary inflammation of the mucous
membrane of the large bronchial tubes, which  terminates in the
formation of pus.  The cough is loud and ringing; the pain in
the front of the chest; the expectoration at first a white frothy
material, but finally pus.
   3d. Chronic Bronchitis is produced by the previous disease
when it has continued for  a long time, and left the mucous
membrane thickened and irritable.
   4th. Capillary Bronchitis affects the membrane  of the fine
tubes; it is dangerous, and causes great suffering.
   5th. Pneumonia is an inflammation of the air-cells and tissue
of the lung, attended by solidification  and  closure of the cells.
It usually  commences at the base of the right lung, and is at-
tended by a dull soreness, cough, and the expectoration has an
iron-rust color.
   6th. Pleurisy is  an inflammation of the serous  membrane
  How do nitrogen and hydrogen act on the system ? How does carbonic acid act ?  How
is the carbonic acid produced in the system conveyed to the lungs ?  What is croup—bronch-
itis—chronic bronchitis? What is capillary bronchitis? What is pneumonia?  What is
pleurisy ? 
                         ANIMAL HEAT.                     131

covering the lung;  it is attended by acute pain, so that the
sufferer tries to suppress the cough as much as possible.   There
•is no expectoration.   It most frequently terminates by the pul-
monary and costal pleura adhering to each other.
   7th. Consumption, also called Phthisis or Tuberculosis, usual-
ly commences at the apex of the left lung, by the deposition in
the  tissue of the organ of small hard masses, called tubercles;
these gradually undergo disintegration, and are converted into
pus, Avhich is expectorated,leaving a cavity. The great consti-
tutional disturbance which  accompanies  the disease assists in
reducing the patient, and death is hastened by the hectic fever
and terrible night-sweats Avhich often appear in the early peri-
od of the attack.
                     LECTURE XXIV.
                         ANIMAL  HEAT.
Definition of Animal Heat.—Paine's Experiments on the Temperature of
  Plants.— Cold and hot blooded Animals.—Relation of the Nervous Sys-
  tem to the Production of Heat.—Allotropic Condition of Carbon and
  other Elementary Substances.—Blushing explained.— Variations in the
  Temperature of the Body.—Temperatures that can be endured by the
  Body.
  By the  term animal heat it is intended to express the  fact
that plants,  and especially animals, possess a temperature dif-
ferent from that of the medium in Avhich they live.  In the case
of plants it is sometimes higher  and at others lower than that
of the air; this is in part due to the fact  that the woody fibre
of which they are composed conducts heat with greater facility
lengthwise than crosswise.  The interior of the  stem of a plant
therefore follows  the temperature of the soil  in Avhich its roots
are placed more closely than that of the air.
  In his  Medical and Physiological  Commentaries, Professor
Paine gives  the results of experiments on the temperature of
plants, Avhich demonstrate that these organisms  generate a cer-
tain amount of heat within their systems, as is shown by the
following table:
     Temperature of the air in the shade, 38° to 52°.
     Temperature of a dead tree, 12 inches diameter, 45°.
     Temperature of Juglans squamosa, 10 inches diameter, buds enlarging, 48°.
  What is consumption ? AVhat is meant by animal heat?  How may the internal temper-
ature of plants be in part accounted for ?  AVhat was the result of Professor Paine's experi-
ments on the internal temperature of plants? 
132
OF COLD-BLOODED ANIMALS.
Temperature
Temperature
Temperature
Temperature
Temperature
Temperature
Temperature
Temperature
Temperature
of Quercus tinctoria, 7 inches diameter, no budding, 49°.
of Castanea Americana, 12 inches diameter, no budding, 50°.
of Salix Babylonica, 18 inches diameter, buds unfolded, 53°.
of Pinus Canadensis, 18 inches diameter, 54°.
of Juniperus Virginiana, 4 inches diameter, 55°.
of Populus laevigata, 4 inches diameter, in bloom, 62°.
of Populus laevigata, 3 inches diameter, in bloom, 65°.
of Populus laevigata, 2 inches diameter, in bloom, 67°.
of Populus laevigata, If inches diameter, in bloom, 68°.
Fig. 108.
Fig. 107.
Air-sac of Fish.
                                               Passing from the
                                            vegetable  to  the
                                            animal  world,  we
                                            find that the lower
                                            forms  of  animals
                                            have a temperature
                                            but  little  higher
           than the  water  or atmosphere they occupy, and
           with the rise and fall of the temperature of the me-
           dium there is a corresponding  and almost immedi-
           ate  change in their temperature.   All the animals
           that present these peculiarities  appertain to the
           cold-blooded class, which  includes fishes and rep-
           tiles.  In  these creatures  respiration is either ac-
           complished by the  skin, by gills, or by rudimentary
           lungs.
              Cold-blooded animals, as a rule, are far more te-
           nacious  of life than those which  are hot-blooded;
           they breathe  more deliberately,  and their tissues
           waste away far less rapidly, so that they can live
           for  very considerable periods  without  food.   The
           amount  of nutriment consumed by them in a given
           time is much less than that required by a hot-blood-
           ed animal of equal weight.   Cold-blooded creatures
           can  also  sustain with  comparative  ease injuries
           which would almost instantly destroy the life of a
           bird or beast, and they sometimes  reproduce  an en-
           tire  extremity that has been lost.
              Men, beasts, birds, and all hot-blooded creatures,
           possess the power of maintaining their temperature
           at a fixed degree.   The respiratory apparatus reach-
           es perfection  in them; the lungs are  more thor-
oughly divided into  air-cells; the rate  of respiration is more
rapid, and the  pulsations of the heart are more frequent, so
  What is a cold-blooded animal ?  What is a hot-blooded animal ?  How is respiration ac-
complished in cold-blooded animals ? Which class of animals are the most tenacious of life ?
In which class of animals is the respiratory apparatus most perfect?
Lung of Reptile. 
THE ORIGIN  OF ANIMAL HEAT.
133
that the blood is passed in a continuous
copious stream through the capillaries.
  It has been already stated that the or-
igin of the heat in  the  system was the
union of carbon  and hydrogen with oxy-
gen ; to this we must add the  oxidation
of "the  sulphur of the muscular and the
phosphorus of the nervous tissue, though
the proportion derived from their com-
bustion may be disregarded when com-
pared  Avith that  obtained from carbon
and hydrogen.
  The  oxidation  of combustible sub-
stances goes on to a certain extent in the
lungs, but the chief action is in the systemic capillaries, so that
heat is produced in the innermost recesses of every tissue of
the body.   Any one who has ascended a lofty mountain will
recollect the peculiar intensity of the cold, which  seemed to
penetrate to the very marrow of the bones, Avhen the thermom-
eter did not indicate a degree of temperature at all commen-
surate  with the  effect on the system.   This is due to the  fact
that at great altitudes the air is rarefied to such an extent that
each inspiration introduces far  less oxygen than is conveyed
into the system at the  level of the sea, consequently there is
a smaller amount of combustible  oxidized;  less heat is pro-
duced  in the interior parts of the body, and  the sensation of
cold is the more intense, because the actual internal tempera-
ture is lower.
  Animal heat being produced by oxidation, some process is
necessary by means  of which any excess of heat may be con-
veyed  out of the system.  This is accomplished by  the evapo-
ration  of water in the form of insensible perspiration from the
skin and lungs, as was explained in treating of the uses of that
liquid  in the system, water requiring an enormous amount of
latent heat in  order to convert it into the gaseous state.
  It was formerly supposed that the heat of the body was pro-
duced by the  nervous system in some mysterious manner, but
we  now know that, though the nervous system does  not origin-
ate  the heat, it regulates the rate of production.
 AVhat is the origin of the heat in the system?  Where does oxidation take place in the
body ?  Why is such an intense degree of cold experienced in ascending lofty mountains ?
How is the excess of heat produced in the body disposed of? What is the relation of the
nervous system to the production of heat ?
 
134  CAUSES  THAT INFLUENCE TEMPERATURE OF  ANIMALS.

   Chemists have shown that oxygen, as well as carbon, hydro-
gen, sulphur, and  phosphorus, present  themselves under  at
least  two allotropic  forms.   In one they are prone to  unite
with  oxygen, and in the other they are indifferent, and  show
little  or no  tendency to go into union.   To the  first state the
term  active has  been applied, while the second is called the
passive condition.
   Electricity possesses control over the condition of these bod-
ies, and can convert them from one state  into the other.   The
nervous force likewise can influence the allotropic condition, as
it  is called, of these elements.   Whenever, therefore, the atoms
of carbon in any given tissue are changed to the active  form,
the flow of discs to  supply them with oxygen  is immediate,
heat is evolved, and  carbonic acid produced.   In this manner
such sudden congestions of the capillaries as that which occurs
in blushing  are readily and rationally explained.   The true re-
lation of the nervous system to the production of the heat of
the body is similar to that which the engineer bears to his en-
gine ; he does not  produce the heat in  the furnaces, but  regu-
lates the rate of production.
   The temperature of various orders of  animals and birds is
determined  to a great extent by their activity.  As an exam-
ple, the swallow, which spends hours on the wing, catching the
flies and other small insects on Avhich it  feeds, has a tempera-
ture of 110°, Avhile the barn-yard fowl, which scarcely ever soars
higher than its  favorite evening perch, has a  temperature of
about 100°.
   In man the average temperature of the body is 98°; but it
varies in its different parts, decreasing as Ave pass from the cen-
tre of circulation to the  extremities.  In the viscera of the ab-
domen it is 101°, while  in the leg it is 93°, and in the  sole of
the foot only 90°.
   Age also  possesses its influence.   At the moment of birth it
is  about  100°, being the same as that of the uterus; it quickly
falls to 99°, but soon rises to 102°, at which  point it remains
throughout  infancy.
   The variations of temperature to Avhich the  human body can
be subjected  with impunity  are far greater than is generally

 What are  the  two allotropic forms ?  How is the allotropic condition of an elementary
body influenced by electricity?  Can the nervous power influence the allotropic condition ?
How may blushing be explained?  How does the activity of an animal influence its temper-
ature ?  What is the average temperature of man ? What is the effect of distance from the
centre of circulation on the temperature ?  How does age influence the temperature of the
body? 
           DIVISIONS OF  THE URINARY APPARATUS.        135

supposed.  The thermometer in the polar regions often indi-
cates a temperature of 60° Fahrenheit, and yet a  seaman  Avill
in the course of a few weeks pass from regions in wriich mer-
cury freezes  to the equator, Avhere the temperature is 130° in
the shade, Avithout serious injury, though the  change in climate
has amounted to nearly 200°.
  Far greater variations  than these can  for a few moments be
borne,  It is stated that a man may enter and remain for a feAV
seconds in an oven, the temperature of which is 600°, providing
the air is dry.   Under these circumstances, the rapid evapora-
tion from  the  surface of the  body prevents the  temperature
rising; but if the air is moist, evaporation does not go on, and
serious consequences immediately arise.
                     LECTURE  XXV.
                  THE URINARY SYSTEM.
Position and Descriptive Anatomy of the Organs forming the Urinary
  System..—Microscopic Anatomy of the Kidney.—Portal Circulation of
  the Kidney.—Properties, Quantity, and Composition of Urine.— Classes
  of Food represented in  the Urine.—Function of the Malpighian Tufts
  and Convoluted Tubes.—Draper's Theory of the Method  of Action of
  the Kidney.

  The third channel by which effete substances  are eliminated
from the  system is  the urinary apparatus.  It  consists of the
kidneys, ureters, and bladder.   The bladder  is  situated in the
pelvic cavity, and is the receptacle into Avhich the urine passes
as fast as it is secreted, and from which it is voided at the de-
sire of the individual.   It consists of a  muscular bag lined Avith
mucous membrane,  and, Avhen distended, will contain a quart
of liquid, or even more.  When it  is subjected  to  too great a
degree of distention it becomes paralyzed, the muscular coat in
some  instances  never  regaining its proper contractile power;
the sufferer loses all control over the organ, and the urine drib-
bles away sloAvly, causing great annoyance and inconvenience.
  The ureters  are tubes  about the diameter  of a  goose-quill;
they pass from the  bladder to the kidney.  There is one  on
each side of the A^ertebral column.   (See Fig. 81.)
  The kidneys are  tAvo in number, one  on each  side of the

  How great are the variations of temperature the body can endure without injury? What
organs compose the urinary apparatus ? Describe the bladder. Describe the ureters.
t 
136
THE  ANATOMY OF  THE KIDNEY.
Section of Kidney.
      Fig. 109.        spinal  column, in  the lumbar  region or
                   loins.  They extend from the eleventh rib
                   to the upper edge of the ileum, and  are
                   about four inches in length, two in breadth,
                   and one inch thick.  They are shaped like
                   a bean, and in the male  adult weigh from
                   4^ to 6 oz., in the female from 4 to 5^ oz.
                   The  kidney is covered externally by a
                   strong fibrous envelope, called the capsule,
                   over the anterior portion of which the per-
                   itoneum passes, the posterior surface being
                   attached by  cellular tissue to the walls of
                   the abdominal caA7ity.
                     On making a section extending through
                   the greater diameter of the organ, Ave find
that it is  composed of an  external or cortical layer, 1 2, Avhich
is dark red in color, and about two lines in thickness, and an
internal or medullary substance, 3  3, of a light red tint.
  The ureter, 6, enters the kidney at the  notch on its concave
border, and expands  into a  conical-shaped cavity, called the
                      pelvis, 5 5; into this  cavity all the mi-
                      nute tubes which form  the cortical and
                      medullary portion  of the  organ empty.
                      The small tubes of the kidney, or tu-
                      buli uriniferi, as they are called, com-
                      mence  in  the cortical portion in a flask-
                      like body, A, called the Malpighian cap-
                      sule, which contains a tuft of blood -ves-
                      sels,/ g h, and is lined by spheroidal ep-
                      ithelium, a c.  LeaAung  the capsule, the
                      first portion of the tubule  is twisted fre-
                      quently on itself as long as it remains in
                      the cortical portion; it is therefore call-
                      ed the  convoluted tube, B C, and is lined
                      with spheroidal cells, b  d.  As soon as
                      it reaches the medullary portion, the tu-
                      bule pursues  a straight course until it
                      empties into the pelvis of the kidney.
                        In Fig. Ill,a represents the straight
tubes, which originate from the convoluted tubes b b, among
Fig. 110
@
Diagram of Convoluted Tube and
        Tuft.
 Describe the position of the kidneys, their size and weight.  What is meant by the corti-
cal and medullary portions of the kidney?  What is the pelvis of the kidney?  AVhat are
the tubuli uriniferi?  What is the Malpighian capsule ? Describe the convoluted tubes. 
THE  BLOOD-VESSELS OF  THE KIDNEY.         137
Avhich the ramifications of the renal  ar-
tery, c c', are shown, and the Malpighian
tufts, a".
  The circulation  in the kidney presents
peculiarities  of considerable interest in con-
nection Avith the theory of the circulation
of the blood; it is therefore worthy of es-
pecial study.
  The renal  artery, as soon as it enters the
organ, commences  to subdivide until the
Fig. 111.
Fig. 112.
Fig. 113.
      '!   A
Convoluted Tubes and Blood-
Tuft and Convoluted Tube.
Diagram of Malpighian
  •Circulation.
                                            branches, a, Fig.
                                            113, are almost ca-
                                            pillary in  their
                                            character. One of
                                            th e minute branch-
es, a f enters the Malpighian capsule, and, subdividing into
small branches, Avhich are convoluted or tAvisted on each  other,
forms the Malpighian tuft, m.   To the artery, as it enters the
capsule, the name afferent vessel is given.  The branches  Avhich
form the tuft reunite and form a trunk, which takes its exit
from the capsule close  to the  entrance of the afferent vessel.
It is called the efferent vessel, ef.
  As is demonstrated by the figure, the efferent vessels do not
unite immediately to form the renal vein, but pass to the con-
voluted tubes,  and,  subdividing, form a capillary system  or
plexus, j9, Avhich covers  their surface,  and by  Avhich the sphe-
roidal cells of the mucous membrane of the tube are nourished.
These  capillary vessels, reuniting, form the  terminal  twigs  of
the renal \em.
  From the facts giA^en in the preceding paragraph, we see that
the kidney possesses on the small scale a circulation which  re-
  How is the renal artery distributed ?  AVhat is the efferent vessel ?  AVhcre does the renal
vein commence to form ? 
138
COMPOSITION OF  URINE.
sembles that of the liver, for the efferent vein commences and
ends in a capillary system, and  is the  anologue of the portal
vein.
   Before we can intelligently discuss the function of the kid-
ney, we must examine into the nature of its  secretion.
   Urine is a yellowish fluid, with a  specific gravity of about
1025.   When first voided it has an acid reaction, but it  soon
becomes alkaline, owing to the formation of carbonate of am-
monia by the decomposition  of  the  urea it contains.   In the
course  of a day, the amount passed by a healthy man is about
thirty-five ounces, but this varies greatly with the quantity of
liquid that has been taken, and the amount of perspiration.   In
the herbivora the urine is alkaline and turbid, while in  the car-
nivora  it is like that of man, acid and clear.
   The  constituents of the excretion are all substances that are
almost completely oxidized.  The nitrogenized group is repre-
sented  by urea  and uric  acid, derived to a  great extent from
the  nitrogenized elements of the food.   The extractive repre-
sents the respiratory group, and  the  chlorides Avere  taken into
the  system  in  the same  form they present  in the  urine, viz.,
common salt.   The sulphates and phosphates are derived from
the  muscular and  nervous tissues, as is  demonstrated by the
fact that increased action of the muscles and nervous system is
followed by an increase in the sulphates and jxhosphates.

                     Analysis of Urine by Berzelius.
     Water....................................... 933.00
     Urea.........................................  30.10)
     Uric acid..............'.....................  1.00,- Nitrogenized.............. 31 42
     Mucus and epithelium...................    .32)
     Extractive and lactates................. 17.14  Non-nitrogenized......... 17.14
     Sulphate of potash........................  3.71)  gu] h   ..................   6
     Sulphate of soda..........................  3.16)    v
     Phosphate of soda.........................  2.94)
     Bi-phosphate of ammonia...............   1.65 > Phosphates.................   5.59
     Phosphate of lime and magnesia......   1.00)
     Chloride of sodium.......................   4.45) /-,,,  .-,              _ _„
     r,,, ■-,  v                     ■, rr,/- Chlorides..................   5.9o
     Chloride of ammonium..................   1.50)
     Silica.........................................   .03                     .03
                               1000.00  Solids......................  67.00
                                      Water...................... 933.00
1000.00
   With the exception of the extractive, the  substances in the
preceding table are all more or less soluble in water, and pre-
  What analogy exists between the circulation in the kidney and the liver ?  AA'hat is the
color, specific gravity, reaction, and diurnal amount of urine ? What is its reaction in the
herbivora ?  Does human urine retain the acid reaction after it is passed ? What groups of
food do the constituents of the urine represent ? What is the composition of urine ?  Which
constituents pre-exist in the blood? 
              METHOD OF ACTION  OF THE KIDNEY.         139

 exist  in  the blood, as has been satisfactorily  demonstrated.
 The soluble ingredients are easily separated by  a mere act of
 filtration, similar to that conducted in the sudoriparous glands;
 and since Ave can without difficulty find in the sudoriparous se-
 cretion the  chlorides, phosphates, sulphates, and urea of the
 urine, Ave accept the theory that these substances are separated
 by the Malpighian tuft, Avhich is analogous to the sudoripar-
 ous gland in its structure  as well as in its  function.   With the
 extractive of the urine the case is different; the  substances
 composing it do not pre-exist in the same form in  the blood;
 they partake of the fatty nature, Containing a great excess of
 carbon and hydrogen, and are devoid of nitrogen.   Since they
 do not exist in the  blood, they must be formed from it by cell
 action or in  some other way.   It Avill be remembered that the
 \yalls of the convoluted tubes are lined  Avith spheroidal secre-
 ting cells, Avhich are freely nourished by the blood brought from
 the Malpighian capsule through the efferent vessel.  It is the
 function of these cells to separate from the blood certain  sub-
 stances, Avhich  are  appropriated  by them, and  converted  into
 the extractive material of the urine.
   The  convoluted portions of the uriniferous tubes are analo-
 gous, both in  their  structure and function, to  the sebaceous
 glands of the skin, Avhich also separate their oily secretion from
 the blood by cell action.   The method  of action of the skin
 and kidneys, therefore, is identical, except that in the skin the
 two systems of glands are separated, Avhile in the kidney they
 are united, forming the convoluted tube.   The straight  portion
 of the  tube merely conducts the fluid secreted by the Malpigh-
 ian tuft and tube  into the pelvis of the  kidney, and thence
 into the ureter and bladder.
   The  separation of the urinary secretion is continuous, and
 not intermittent, as might be  supposed.   The tufts and cells
 are never at rest from the  day of birth until death.  If any
 thing occurs to  interfere Avith their action, it is immediately
 shown by the blood-poisoning which takes place, the urea  and
 extractive accumulating in  the system,  and producing coma,
 Avhich  rapidly proves fatal unless it is relieved.
   The  action and function of the kidney may be briefly sum-
med up as follows:  The renal  artery delivers to the organ im-
  How and by what mechanism are they separated ?  How and where is the extractive
separated? AVhat glands of the skin are analogous to the convoluted tubes?  Is the secre-
tion of urine continuous or intermittent?  What is the effect of a non-secretion of urine?
Explain the action of the kidney. 
140          METHOD OF  ACTION OF THE KIDNEY.

pure blood, laden with urea and other deleterious ingredients.
It gradually subdivides, until finally small arteries are formed,
called the afferent vessels;  these enter the capsule at the ter-
mination of the uriniferous tube, and, dividing into capillaries,
form the Malpighian tuft, which separates the water, salts, and
nitrogenized constituents  of the secretion.
  From the Malpighian capsule the blood is brought by the ef-
ferent vein, which passes  to the walls of the convoluted tubes
to form a capillary system that nourishes the spheroid cells, by
which the extractive is secreted.  In this capillary system the
twigs of the renal vein originate, and the blood is returned in
a purified condition to the vena cava ascendens.   The aqueous
fluid, with its dissolved salts, that was filtered through the Mal-
pighian tuft, passing into the convoluted tube, washes the ex-
tractive into the pelvis of the kidney, and thence to  the blad-
der, where the urine  is retained, until the distention of the or-
gan and the pain produced induces us to empty it.
                    LECTURE XXVI.
                  THE URINARY SECRETION.

Rapidity of Excretion of deleterious Substances by the Kidneys.—Experi-
  ments on the Origin of Urea. — Effect of Diet and Exercise on the
  Amount of Urea excreted by the Kidneys.

  The rapidity with which deleterious substances are  con-
veyed out of the system is shown by the fact that if a dose of
iodide of potassium is taken, it may be found, by suitable tests,
in the urine passed ten minutes afterward.   Not only are salts
quickly removed from the system by the kidneys, but organic
substances are also rapidly eliminated, for we are all acquaint-
ed with the peculiar disagreeable odor which one  of the  con-
stituents of asparagus gives to the  urine passed immediately
after eating that vegetable.
  Urea is the most important of the constituents  of the urine
as regards quantity, forming nearly one half of the total solid
residue;  it has therefore been the subject  of special examina-
tion, many supposing  that it represents the disintegration of
muscular tissue.

  What is the function of the bladder ? Give some examples illustrative of the rapidity
with which deleterious substances are excreted by the kidneys.   What opinions are held re-
garding the origin of urea ? 
EXPERIMENTS ON UREA.
141
  In my thesis for the degree of Doctor of Medicine, published
in the New York Journal of Medicine for February, 1856, it is
shoAvn that in all probability urea merely represents the excess
of nitrogenized material consumed; I therefore introduce it in
support of that opinion.
  Is the Urea in Urine due to Muscular Motion f—The first
step in  the solution of such an  inquiry as the  above is  the
choice of some reliable process by which analyses determining
the amount of urea in various samples of urine may be made.
  The process employed in the folloAving experiments consists
essentially in  the  decomposition of the urea  by nitroso-nitric
acid, and then determining the carbonic acid  produced by
means of hydrate of baryta.
  Next we have to settle upon some  standard Avith which, the
results obtained in our experiments  may be  compared.  The
one chosen as being the most convenient is the total quantity
of urea passed in twenty-four hours, a Aery small amount of ex-
ercise being taken; the diet being mixed, and  as nearly as pos-
sible the same in amount each day.
  The analyses given in the folloAving table fulfill these condi-
tions, and, with the exception of the eleventh, twelfth, and thir-
teenth, were all obtained from the  same individual.  In addi-
tion to the urea, the solid residue, that is, the solid material left
after the evaporation of the Avater  contained in the excretion,
Avas also determined.
Average daily amount of motion, 3 miles.			
Analysis.	Urine.	Solid Residue.	I'rea.
	In Grammes.	In Grammes.	In Grammes.
1	754-000	44-488	23-649
2	1227-000	52-768	26-030
3	1153000	54-202	26-034
4	1042-000	60-456	31-902
5	1160-000	60-825	31-008
6	990-000	56-493	27-567
7	. 1737-000	66-874	31-062
8	1042-000	53-943	26-551
9	997-000	55-288	27-616
10	1079 000	54-513	23-873
11	871-000	55-598	25-271
12	775-000	51440	27-323
13	743-000	51-023	26-816
14	974-000	52-718	24-476
15	1462-000	59-838	28-424
16	768-000	50-120	24-394
17	1595-000	62 -096	29-232
18	1536-000	57-838	28621
Total for 18 da	ys, 19905-000	1000-521	489-849
Mean for'24he	urs,110G-	55-584	27-213
What is the average amount of urine, solid matter, and urea excreted in a day ? 
142
EXPERIMENTS ON UREA.
  If we compare the urea with the solid residue in the manner
proposed by Dr. Simon, the result of these analyses is the same
as of those given by Berzelius; Lehmann, and others.

              1000 Parts of Solid Residue contain, according to
    Berzelius..................................................................... 451- of Urea.
    Lehmann..................................................................... 490" " "
    Marchand.................................................................... 492- " "
    Above Analyses............................................................. 490* " "

  Our standard, therefore, is as follows, in grammes :
Urine.	Solid Residue.	Urea.	li.OO of s. K. contain of Urea
1106-	55-584	27213	490-
  We may now proceed to determine, 1st. The daily quantity
of urea excreted in absolute rest;  2d. That during violent and
sudden muscular action.
  The Amount in Absolute Pest.—In order to  obtain  this, I
analyzed the urine of the patient whose history is given below.
  C. Marshall, aged 22, a Virginian by birth, had his leg bro-
ken by an accident on the  Panama Railroad as he was return-
ing home; ten days  after the  accident he  entered the New
York Hospital, where he was treated.  Nothing unusual oc-
curred, and  at  the expiration of eight weeks he was dis-
charged, cured.  Diet AAras mixed, being the usual hospital al-
lowance.
  The following samples of urine were obtained after  three
weeks of confinement, and therefore represent the urine of ab-
solute rest.
.Analysis.	Urine.	Solid Residue.	1 rea. |
19 20 21	In Grammes. 871-775-743-	In Grammes. 55-598 51440 51-023	in Grammes. 25-271 27-323 26-816
Total for 3 days, 2389'		158-061	79-410
Mean for ?4 hours, 796"		52-687	26-470
1000 of Solid Residue contain 502 parts of Urea.			
  Comparing these results with our standard, Ave obtain the
following table:
	Total Urine.	Solid Residue.	Urea.	1000 of S. R. contain of Urea
	1106-796-	55-584 52-687	27-213 26470	490-502-
Absolute Rest...				
From this we see that there is a small diminution in the to-
What is the effect of absolute rest on the formation of urea ? 
EXPERIMENTS ON UREA.
143
tal quantity of solid residue and urea excreted in a state of ab-
solute rest, but the solid residue is richer in urea.
  The Amount of Urea excreted in violent Muscular Action.—
For the purpose of determining this, I walked at different times
a distance of thirteen miles on a level causeAvay, the greater
portion  being performed at the rate of four and a half miles an
hour, the pulse in each trial rising to above one hundred. Diet
same as in the standard.
Average daily amount of motion, 13 miles.			
Analysis.	Total Urine.	Solid Residue.	Urea.
22 23	1042-768-	53-943 50-120	26 551 24-394
Total for 2 days, 1810"		104 063	50-945
Mean for 24 hours, 905"		52 031	25-472
1000 of Solid Residue contain 489- parts of Urea.			
  Comparing this with our standard, we obtain the folloAving
table:
	Urine.	Solid Residue.	Urea.	1000 of S. R. contain of Urea
	1106-905-	55-584 52-031	27213 25-472	490-489-
Violent Motion...				
which demonstrates that when  sudden and violent exercise is
taken, the total amounts of solid residue and urea are dimin-
ished, while the proportion of  urea to  solid residue remains
about the same.
  Now if the urea in urine was altogether the product of mus-
cular disintegration, the  conditions Avhich prevailed in experi-
ments 22 and  23 would have  greatly increased its  amount;
but, instead of this, Ave find that in the same individual, and
under otherwise the  same circumstances, violent muscular ac-
tion does not increase the total quantity of urea passed in  a
day.
  Again, in a state of absolute rest, if the urea was owing main-
ly to the disintegration of tissue from exertion, we should ex-
pect to find a comparatively small amount of that  substance
present, and this quantity would represent the  destruction of
the muscular tissue  engaged in carrying on the process of or-
ganic life.  But, instead of this, we find from experiments 19,
20,  and 21, that in rest as perfect as can be obtained there is no
great diminution in the total quantity of urea excreted, and
that the solid residue left after the evaporation of the Avater is
actually richer in urea.
  We therefore conclude that violent and brief muscular action
What is the effect of violent muscular action ? 
144
EXPERIMENTS ON UREA.
does not exercise  any great influence on the urea  in urine.
Nor is it probable that that substance has passed out of the
system through the skin as  an ingredient of the sweat.   It is
also equally improbable that it has escaped by way of the in-
testinal canal, for urea is not a normal ingredient of fsecal mat-
ter, except when the kidneys are exsected, or their function is
in some way disturbed.   But Ave are supposing that an excess
of urea has been formed, and the reason we give for this sup-
position is, that if such violent action  Avere continued for  a
great* length of time, the muscular structures would greatly de-
crease in Aveight.   And as urea contains a large quantity of ni-
trogen, which is also a characteristic component of muscle, Ave
therefore say that urea represents the disintegration of muscle.
But may it not be that the nitrogen contained in the destroyed
tissue has escaped directly through the lungs, without entering
into composition with other substances ?   This is not at all im-
probable, for the experiments of MM. Regnault and Reiset on
respiration have shown that warm-blooded animals, under the
usual circumstances in which they exist, excrete  by means of
their lungs an amount of nitrogen equivalent to from y^j to -^
of the oxygen consumed.
   It has  been supposed, from the  experiments of Dr. Simon,
that violent exercise increased the  amount of urea; but if we
examine his analyses as  they are given  in his " Chemistry of
Man," it will be seen that as the amount  of urine is not given,
Ave have  no means of knoAving whether the  total quantity of
urea was increased or  not.  Indeed, it is more probable that
the apparent increase is owing to the loss of water by evapora-
tion.   The'same objection is to be urged against the analyses
of Dr. Percy.
   Lehmann gives in his Avork two experiments on the influence
of exercise on the quantity of urea.  In these, severe bodily
exercise increased the amount from thirty-two grammes to thir-
ty-six in twenty-four hours on one occasion, and to thirty-seven
on another.  It is true that in this case  wTe  have an increase,
but it  is not more  than analyses made from day to day would
show.
   We therefore conclude, from the experiments thus far made,
that sudden and violent exercise does not increase, to any ex-
tent, the amount of urea in urine.
   As it is evident that exercise does not exert any material in-
fluence on the fluctuations of urea, we must seek  for other
causes, and among these  is diet, which has been shown, by the 
EXPERIMENTS ON UREA.
145
experiments of Lehmann, to exert a most notable influence, as
may be seen in the folloA\Ting table :
	Total I'rine.	Solid Residue.	Urea.
Animal Diet	1202-	87-44	53-198
Mixed "	1057-	67-82	32-489
Vegetable "	909-	59-23 .	22-481
Non-nitrogenized "	---	41-68	15-410
  From this Ave observe that in animal diet there  are nearly
four times as much urea excreted as in a non-nitrogenized one;
and if we compare it with the solid residue, Ave find that in a
non-nitrogenized diet the solid residue contains far less urea
than in an animal  one.
  Comparing these results with those obtained from the exper-
iments given on exercise, we see how great the influence of diet
is, and hence Ave should be led to  suppose that there must be
a considerable difference in the amount of urea excreted during
the day, compared with that  excreted in the  night.  Accord-
ingly, we come to  the second inquiry, viz., What are the semi-
diurnal  variations, and Avhat.is  the influence  of rest  and mo-
tion on them '\
Average daily amount of motion, 13 miles.							
		Night Urine.		Day Urine.			
Anal.	Urine.	Solid Residue.	Urea.	Urine.		Solid Residue.	Urea.
27				678		35 -802	17-448
28	479-	25-023	13-560				
29				4*42		26-406	11-985
30	547-	30-087	15-582				
31				627		31-618	14-112
32	413-	22-325	12-439				
33	...			473		26-022	10-464
34	606-	28-491	13-409				
35				561		33-709	14-216
36	310-	21-889	11-055				
37				413		26-809	14-426
38	362-	24-631,	12-897				
39				443		31-492	16-800
40	300-	19-531	10-016				
41				354		22-000	11-612
42	620-	30-718	12-864				
43				516		30-505	13-371
44	946-	29-333	15 053				
45				502		30-161	13-709
46	266-	19-959	10-685				
47				620		34-774	14-912
48	975-	27-322	14-320				
49				916-		33-000	15-694
50	620-	24-833	12-927				
Total	6444-	304-142	154-807	6545		362-298	168-749
Meat	i 537-	25-345	12-900	545-		30-191	14-062
1000 o	1 Solid Resi	iue contain 50!)- parts of Urea.		1000 of Solid Residue contain 4			66- parts of Urea.
Difference betw*		en the percentage of Urea in th		3 Solid Residue of the day and n			lght, 43- in 1000.
AA7hat is the effect of diet on the amount of urea ?
               K 
146
EXPERIMENTS ON UREA.
  Of the Semi-diurnal Variations.—These have not as yet been
noticed by any one who has experimented with urine.  They
are  very marked and uniform in their  occurrence, and much
more apparent than the fluctuations caused by exercise.  In or-
der to  show them, the preceding analyses of urine Avhich was
passed during the day, compared with those of the urine void-
ed in the subsequent night, are given.  The day was reckoned
from 7 A.M. to  7 P.M., when the night period began.
  Diet in these experiments was mixed, and about the same in
quantity each day.   A moderate amount of exercise was taken.
  These analyses demonstrate that the total amounts of solid
residue and urea passed in the  course  of the day are  much
greater than those voided during the night, while the solid
residue of the urine excreted in the night is richer in urea than
that of the day.
  These results  are doubtless owing to the influence of diet;
for, during the day, food having been ingested, the elimination
of the excess begins to take place almost immediately, thus pro-
ducing  an  increase in the  amount of urea; AA7hile during the
night, though the total quantity  of urea excreted is less, yet it
forms a larger portion of the  solid residue.  This may be at-
tributed to the  fact that in the day a greater amount of phos-
phates and sulphates being formed, these, Avith the  chlorides
and other salts taken in at the same time, diminish the propor-
tion of urea to solid residue.                           f
  If this explanation is the true one, we should expect to find
that in absolute rest the amount of sulphates, etc., being less,
the difference between the percentage of urea in the solid resi-
due of the day, compared with that of the night, would also be
less.  But if violent muscular  action was undergone, these dif-
ferences should become  greater on account  of the increase of
the amount of sulphates, etc.
  In order to demonstrate that this is so, the following analy-
ses  are given.
  The Influence of Pest on Semi-diurnal Variations.—For the
solution of this problem, the urine of the patient  Marshall,
whose history is given above, was used.  Analyses of the urine
of three days were made.
What do the semi-diurnal variations show ? 
EXPERIMENTS ON UREA.                147
		Night Urine.		Day Urine.		
Anal. | trine.		Solid Residue.	Urea.	Urine. I Solid Residue.		Urea.
51				561-	33-709	14-216
52	310-	21-889	11-055			
53				413-	26-809	14-426
54	362-	24-631	12-897			
55				443-	31-492	16-800
56	300-	19-531	10-016			
Total 972-		66-051	33-968	1417-	92-010	45-442
Mean 317-		22-017	11-322	472-	30-670	15-147
1000 of Solid Residue contain 514-			parts of U,jea.	1000 of Solid Residue contain 493- parts of Urea.		
Difference between the percentage of Urea in the Solid Residue of the day and						night, 21- parts
			in 1000.			
  From  this we see, that in absolute  rest the difference be-
tAveen the percentage  of urea in the solid residue of the day
compared with that of the night is only twenty-one parts in
one thousand, while, when a small amount of exercise is taken,
it is forty-three parts in  one thousand;  this is what we should
have expected to find if the  explanation we have given of this
variation was the true one.
  The Influence  of Violent Exercise on the Semi-diurnal Varia-
tions.—On the days on which  these  samples of  urine  were
passed, the same amount of exercise was taken as in the former
experiments on A7iolent muscular action.
Average daily amount of motion, 13 miles.						
Night Urine.				Day Urine.		
Anal.	Urine.	Solid Residue.	Urea.	Urine.	Solid Residue.	Urea.
57 58 59 60	413-266-	22-325 19-959	12-439 10-685	627-502-	31-618 30-161	14-112 13-709
Total 679-		42-284	23-124	112!)-	61-779	27-821
Mean 239-		21-142	11-562	564-	30-889	13-910
1000 of Solid Resi		iue contain 546- parts of Urea.		1000 of Solid Residue contain 4		50- parts of Urea.
Diff	jrence betw	een the percentage of Urea in t in 1		le Solid Residue of the day and MO.		night, 96- parts
  On examining the result of these analyses, we find that the
difference of the percentage of urea in solid residue is as much
as ninety-six  parts in one  thousand, thus giving additional
proof that our supposition concerning the cause of these varia-
tions is the true one;  and by comparing them together, we ob-
tain a table which is almost an index of the amount of exertion
undergone.
Table of apparent Variations of percentage of Urea in Solid Residue of day and night in different degrees of
                            Motion.
     Absolute Rest............................................................ 21 parts in 1000
     Moderate exercise...................................................... 43 "  "
     Violent    "  ...................................................... 96 "  " "
  The onlv other  cause  to Avhich these fluctuations could be
What is the effect of exercise on the semi-diurnal variations ? 
148               EXPERIMENTS  ON UREA.
                                                         V
attributed would be variations in the  amount  of urea itself.
Now, if this was the case, there would be more  urea  excreted
in the night than in the day.  But if we examine the following
table we find the opposite condition holds.
Table of Variations of total Amount of Urea passed in the day and in the night during different degrees of Exercise.		
	Day Urea.	Night Urea.
	15147 14-062 1^910	11-332 12-900 11-562
		
		
  We therefore conclude that the fluctuations of the percent-
age of urea in the solid residue of the day compared with
that of the night are due to the excretion of the phosphatesre-
sulting from mental action, and to the sulphates formed during
muscular activity.
  We have also supposed that the cause of the increase of the
total amount of urea during the day was due to the ingestion
of food.  In support of this, we give the following analyses:
  In these, the tAventy-four  hours are divided into five periods.
The first four consist of four hours each, and extend from 6 30
A.M. to 10 30 P.M.; Avhile the fifth is eight hours long, and ex-
tends from 10 30 P.M. to 6 30 A.M.  As regards  the time at
which meals  were taken—breakfast, a  light meal, at 7 A.M.;
dinner,  constituting the main meal, at  3 P.M.; and tea  at 7
P.M.  A moderate amount  of exercise was taken in the morn-
ing.
First Period, from 6 30 A.M. to 10 30 A.M.			
Analysis.	Total Urine.	Solid Residue.	Urea.
61 62 63 64	221-162-177-177-	11-754 9-270 8-516 10-468	5-963 4-312 3-763 5-000
Total 737-		40-008	19-038
Mean 184-		10-002	4-759
1000 of Solid Residue contain 475 parts of Urea.			
Second Period, from 10 30 A.M to 2 30 P.M.					
Analysis.		Total Urine.	Solid Residue.	Urea.	
65 66 67 68		280-147-236-147-	12-782 7-688 10-882 8-427	6-001 3-338 4-552 4-188	
Total	810-		9-779	18-079	
Mean	202-		9-945	4-519	
	1000 of Solid Residue contain 454 parts of Urea.				
 
EXPERIMENTS ON UREA.               149
Third Period, from 2 30 P.M. to 6 30 P.M.			
Analysis.	Total Urine.	Solid Residue.	Urea.
69 70 71	177-133-214-	11-266 9-448 12-220	5-484 4-335 5-797
Total 524-		32-934	15-616
Mean 175-		10-978	5-205
1000 of Solid Residue contain 473 parts of Urea.			
Fourth Period, from 6 30 P.M. to 10 30 P.M.			
Analysis.	Total Urine.	Solid Residue.	Urea.
72 73	184-192-	10-534 10-571	5-629 5-417
Total 376-		21-105	11-046
Mean 188-		10552	5-523
1000 of Solid Residue contain 523 parts of Urea.			
Fifth Period, from 10 30 P.M. to 6 30 A.M.			
Analysis.	Total Urine.	Solid Residue.	l rea.
74 75 76	295-221-340-	14-489 11-754 13-772	7-931 7-022 8-347
Total	856-	40-015	23-300
Mean	285-	13-338	7-766
1000 of Solid Residue contain 582 parts of Urea.
  If Ave collect together the results furnished by these analyses,
we obtain the following table :
Period.		No. of	Total	Solid	Urea.	1000 Solid Residue
		Hours.	Urine.	Residue.		contain of Urea
1	From 6 30 to 10 30	4	184-	10-002	4-759	475-
2	" 10 30 " 2 30	4	202-	9-945	4-519	454-
3	" 2 30 " 6 30	4	175-	10-978	5-205	473-
4	" 6 30 " 10 30	4	188-	10-552	5523	523-
5	" 10 30 " 6 30	8	285-	13 338	7-766	582-
  From this table we find that the period of the day at which
the greatest amount of urea is  excreted begins about dinner,
and continues for a time after tea.   The period at which the
next greatest amount is  excreted is just after breakfast, while
during the eight night hours far less is excreted than during
the same time in the afternoon.
  We therefore  conclude that, as the ingestion of food can exer-
cise so rapid and marked an influence on the quantity of urea,
it is the cause of the increased excretion of that substance dur-
ing the day.
  Reviewing the results arrived at, we conclude finally:

                        CONCLUSIONS.
  1. Exercise  does not increase to any extent  the  amount of
urea in urine. 
150    DETERMINATION  OF SPECIFIC GRAVITY OF URINE.

  2. The  ingestion  of  food  during the day causes a greater
amount of urea to be  excreted at that time than is excreted
during the night.
                    LECTURE XXVII.
                   EXAMINATION OF URINE.
Methods for determining the Specific Gravity and Reaction of Urine.—
  Tests for an Excess of Urea.— Uric Acid.—Sulphates and Phosphates.
  —Tests for Albumen.— Origin of Albuminous Urine.—Tests for Blood
  in Urine.—Tests for Bile.—Pettenkofer's and Heller's Tests.—Diabetic
  Urine.—Moore's and Trommels Tests for  Sugar.—Mauminr's Test.—
  The Fermentation Test.—Detection of Pus.

  Since urine is one of the chief channels by which effete ma-
terials are voided from the system, it becomes a matter of great
interest, especially to physicians  and invalids, to know the
methods by AArhich we may determine any improper increase in
the ordinary ingredients of the secretion, or detect the appear-
ance of new and abnormal substances.
Fi    The first step in the  examination of a sample of urine is
"*•'  to notice its color and the quantity passed.   The  specific
  :  gravity should then be determined.  This  is done by
    means  of a small instrument  called  the  urinometer, Fig.
    114.  It is  an  ordinary areometer, adapted to the exam-
    ination of urine, and indicating specific gravities from 1000
    to 1060, within which limits the specific gravity  of the
    urine generally falls, that of normal urine being from 1020
    to 1030.
      In using  this instrument, the liquid should be  poured
    into the cylinder without making a foam.   This may be
accomplished by holding the jar in an inclined position, at an
angle of about 45°; the fluid will then  run down the side with-
out making any froth, if it is poured in gently.  If the specific
o-ravity of the sample is above 1040, we may suspect the pres-
ence of sugar; but excess of urea will give a similar result.  If
it is very low, and continues so for many days, the urine prob-
ably contains albumen.
  The reaction is  determined by the use of litmus paper, which
may be bought  at the apothecaries', or  at a chemical furnishing
  How is  the specific gravity determined ?  What is the specific gravity of healthy urine ?
What is the urinometer ?   How is the formation of a foam to be avoided ? How is the re-
action determined? 
TESTS FOR  URIC ACID.
151
store.   Blue and red paper should be provided.  The test is
peiformed by dropping portions of paper of both colors into
the liquid; if they are red, it  is acid; if they are both blue, it
is alkaline; if one is red and the other blue, it is neutral.
   When voided, healthy urine is nearly always acid;  but in a
short time, depending on the temperature, it commences  to de-
compose, ammonia being formed, and the" reaction becoming al-
kaline.  When the  urine is highly alkaline at  the time it is
voided, and especially if it has  a putrid or ammoniacal odor,
there is  some irritation or inflammation in one of the divisions
of the urinary apparatus, generally the bladder, that causes an
increase in the  amount of mucus, which promotes the decom-
position of the urine to such an extent that it commences Avhile
it is yet in the bladder.
   The constituents  of healthy  urine  that are  increased by
disease are, Urea.  The ordinary amount of this ingredient is
about 30 parts in 1000.   As long as it is present in proper pro-
portion, the specific gravity of the secretion is below 1030;  but
if it increases in quantity, the  specific gravity  rises, and  the
urine, on the addition of nitric acid, forms crystals of nitrate of
urea at a temperature of 60°.  A strong solution of oxalic acid
will produce, under the same  conditions, crystals of oxalate of
urea, if the mixture is kept in a  cool place.
   An excess of uric acid is usually accompanied by a high  col-
or.  After a short  time, a crystalline precipitate, commonly
called the  brick-dust deposit, is formed: it is in part produced
by the urine cooling, and  in  part by its decomposition.   The
deposit rarely consists of pure uric acid,but contains in addi-
tion urate  of ammonia and urate of soda,  together with  color-
ing matter.
   Uric acid  may be obtained, for the purpose of examination
and study, by adding to a pint of urine about half an ounce of
hydrochloric acid, and setting the mixture aside for twenty-
four hours or longer.  By this  method large  crystals of uric
acid of a reddish color may be procured in any desired  quan-
tity, by employing a sufficient amount of urine.
   Placing  some of the crystals obtained in the above manner
on a slip of platinum foil, and raising them to a  red heat, they
undergo oxidation, and an odor similar to that produced by
  What is the reaction of freshly-passed urine ? AVhy does it become  alkaline ?  In what
disease does it turn alkaline in the bladder?  What is the ordinary proportion of urea in
urine ?  How may an excess of urea be detected ? What change does an excess of uric acid
impress on the color of urine ?  In what forms may uric acid be present in urinary deposits ?
How may uric acid be prepared from urine ? AVhat is the odor given by burning urie acid ? 
152       TESTS FOR PHOSPHATES AND SULPHATES.

burning hair is evolved.  If the crystals have been produced
in the natural manner, i. e., by the gradual decomposition of
the urine, a  large amount of residue will remain on  the foil,
which is composed chiefly of phosphates of lime and soda, with
a trace of sulphates.
  The most reliable chemical test for the presence of uric  acid
is the murexide test.  It is performed by placing a few crys-
tals in a watch-glass, or other small dish, adding a little strong
colorless nitric acid, and evaporating carefully to dryness.  A
yellow residue remains, to which dilute ammonia is to be add-
ed.   A beautiful reddish-purple color is immediately produced,
to which the name of murexide is given.
  The phosphcttes are often present in such excess as to form a
copious deposit soon after the urine is  passed.  If the  urine is
heated before the  sediment forms, a  cloudy precipitate is  pro-
duced, which is readily dissolved by  the  addition of a  few
drops of nitric acid.   The deposit of phosphate may be distin-
guished from urate of ammonia by the fact that if it is  warmed
with  some of the urine in a test tube, the urate dissolves, while
the phosphate remains undissolved.  It  often happens that
urate and phosphate are both present  in excess; when this is
the case, the murkiness caused by the precipitated urate dis-
solves on the first application of the heat, the liquid becoming
clear, and remaining so for a few seconds;  it then becomes tur-
bid again, owing to the precipitation of the phosphates by the
continued heat.  From  deposits of  uric  acid those  of phos-
phates may be distinguished by the addition of a few drops of
nitric acid, the phosphates or urates  being  immediately  dis-
solved, but uric acid remaining untouched by the dilute acid
that is formed, though it readily  dissolves in pure, strong acid.
  The sulphates are not often made the subject of examination,
but they may be readily determined by acidulating a measured
quantity of urine with an excess of hydrochloric acid, and then
adding from a burette  a graduated solution of chloride of ba-
rium.  When the test ceases to produce a precipitate, the quan-
tity that has been used is read off on  the  scale, and from the
result obtained the amount of sulphates in the sample can be
calculated.   For a more extended explanation of such volu-
metric processes the  reader is referred to chemical works.
  Describe the murexide test.  What is the effect of heat on samples of urine containing an
excess of phosphates ?  How does phosphatic urine act with nitric acid ? How may a de-
posit of phosphates be distinguished from one of urate  of ammonia? How may a deposit of
phosphates be distinguished from one of uric acid? How may an excess of sulphates be de-
tected ? 
TESTS FOR  CHLORIDES  AND  ALBUMEN.         153
   The chlorides  are  said to be  affected in pneumonia.  They
 may be determined by acidifying Avith a considerable excess of
 nitric acid, and then adding a graduated solution of nitrate of
 silver, as in the preceding example.   From the quantity of sil-
 ver solution used, the amount of chlorides present may be esti-
 mated.
   From variations in the normal constituents  of the urine, Ave
 now pass  to  the consideration of  the abnormal  substances
 which from time to time appear in the secretion; among these,
 the chief are albumen, bile, blood,  chyle, and sugar.
    Urine containing albumen usually has a specific gravity be-
 Ioav 1025;  sometimes it falls to 1004.  This  is by no means
 uniform, for I have often  examined specimens  Avhich had  a
 specific gravity higher than 1030, and yet they were  laden with
 albumen.
   Albuminous urine is also usually light colored, but this is by
 no means a reliable distinction.  The tests by which albumen
 may be detected are,
   1st. Heat.  Place in  a test tube  some of the suspected urine,
 and raise its temperature.   Before the boiling point is  reached
 a cloudy precipitate forms, which  might be mistaken for phos-
'phates, but  may  readily be distinguished from it by the addi-
 tion of a few drops of nitric acid,  Avhich dissolves  the phos-
 phates, but leaves the coagulated  albumen untouched.   If the
 urine  is highly alkaline, heat will often fail to give a  precipi-
 tate, if the  quantity of albumen is small;  under these circum-
 stances, the liquid must be acidified before heat is applied.
   2d.  Nitric acid. Add to some  urine in a test tube a few drops
 of nitric acid; the albumen present is immediately precipitated
 in a cloudy form.  Other bodies will also produce a precipitate
 with nitric  acid.  If there  is a large  excess  of uric  acid or
 urates, they will form a precipitate  of minute  crystals  of uric
 acid, or  nitrate of urea, Avhich is easily mistaken for the albu-
 minous  cloud.  If the patient is taking cubebs or copaiba for
 disease of the urinary apparatus, a similar precipitate is formed
 by the addition of nitric acid, which  arises  by its producing an
 insoluble compound with certain principles contained in those
 medicines.
  How may an excess of chlorides be detected ? Mention some of the abnormal substances
 found in  urine.  What is the effect of the presence of albumen on the specific gravity of
 urine? Does albuminous urine always possess a  low specific gravity?  What is the color
 of albuminous urine?  What are the tests for  albumen?  How may the albumen precipi-
 tate by heat be distinguished from the phosphate precipitate ?  Will  heat give a precipitate
 in highly alkaline urine that is albuminous ? Under what circumstances will the nitric acid
 test for albumen lead to error ? 
154
TESTS FOR  BLOOD.
    3d. Bichloride of mercury, tannin, and a  number of other
 substances produce precipitates Avith albumen;  but the tests
 in ordinary use are nitric acid and heat, Avhich answer all re-
 quired purposes, if they are employed with judgment.
    Albumen  sometimes  appears in the urine for a  short time
 Avhen the diet has  contained a superabundance of that  sub-
 stance.   In the exanthemata, especially in scarlet fever, it ap-
 pears for a time.  The urine of pregnant women also at times
 contains  albumen.  With these exceptions,  its presence is al-
 Avays to be regarded as  a symptom of more or less serious dis-
 ease of the kidney, in which the spheroidal cells of the convo-
 luted tubes  and the Malpighian tuft are involved.   It doubt-
 less often commences as an acute disease, and recovery is possi-
 ble ; but in  the great majority of instances the organs men-
 tioned undergo structural change, the spheroidal epithelium of
 many of the tubes being destroyed, and the  kidney finally un-
 dergoing granular or fatty degeneration.  So common is dis-
> ease of the kidney among the lower classes, that out of nearly
 500 post-mortems I witnessed or  made in Bellevue Hospital
 during my term of service in that institution, I  only saw per-
 fectly healthy kidneys in two adult subjects.
    Albumen  may be present because  the urine contains blood,
 bile, or chyle; but we shall treat of such cases when consider-
 ing those abnormal ingredients.
    Blood in urine may be derived from the bladder, ureter, or
 kidney.'  When it has come from the bladder or ureter it usu-
 ally forms clots of greater or less size, depending on the rapid-
 ity with which it has been poured out.  When it is  derived
 from the kidney it rarely forms a clot, but gives to the urine a
 uniform reddish or brown color.  When a sufficient period has
 elapsed it forms a deposit, which, under the microscope, is found
 to be composed of blood discs.
    When urine containing blood is heated in  a test tube, the al-
 bumen of the blood,  as it coagulates, entraps the  discs, which
 give to the precipitate formed a broAvn tint, that distinguishes
 it from the white  cloud produced when the urine  contains albu-
 men  only.   Nitric acid  also gives in bloody urine a dark-col-
 ored coagulum, that produced in albuminous urine being white.

 ' Under what circumstances does urine contain albumen temporarily? What is the state
 of the kidney when the albumen is always present?  With what substances does albumen
 occur ?  From what sources may blood in the urine be derived ?  How may we distinguish
 between blood from the kidney and from other parts of the urinary apparatus ? What is
 found in the deposit formed when it is examined under the microscope ?  How docs urine
 containing blood act when it is heated ?  How does it act with nitric acid ? 
TESTS FOR  BILE.
155
  When the microscope fails to detect blood discs, as  is the
case in purpura, the presence of the dissolved corpuscles in the
urine may be proved by evaporating a portion of the fluid to
dryness, incinerating the residue, dissolving the ash in nitric
acid, and applying the tests for iron..  If it is found in consid-
erable quantity, it is derived from the hsematin of the dissolved
discs.
  In albuminous  and bloody urine a sediment deposits, in
which casts from the tubuli uriniferi may be found by a micro-
scopic power of about 200.   These casts are often almost col-
orless, and not easily seen in the fluid; at other times their
surfaces are covered Avith kidney cells, Avitlt fatty and granular
substances, or even blood discs.  Their presence is  a valuable
indication  of the state of the kidney, for they enable us to de-
termine to what  extent  the  disease of the organ has advanced,
and to give an intelligent prognosis regarding the prospect of
future recovery.   Their absence is a favorable symptom, but
their presence unfavorable, rendering great care on the part of
the sufferer necessary in order to prolong life.
  Urine containing bile usually has a yelloAvish or greenish-
broAvn  color.   The tests by Avhich this substance may  be de-
tected are, Pettenkofer's test, Avhich is conducted in the fol-
lowing  manner.  The albumen is first  separated by boiling the
urine and collecting the coagulum formed on a  filter;  if the
urine is alkaline, enough acid  should be added to change its re-
action, but no more.  The filtered urine is then placed in a test
tube, which should be immersed in a glass of cold water, so as to
keep the mixture to be made in the tube at a low temperature.
An amount of sulphuric acid equivalent to about two  thirds
the bulk of the urine employed should then be poured drop by
drop into the tube ; if it is added too rapidly, the temperature
Avill rise too  high and the test will  fail.   A small piece of
white sugar is then dropped into the mixture, and the arrange-
ment set aside.  After the lapse of a sufficient period of time, de-
pending upon the  quantity of bile in  the  sample, a blood-red
color commences to appear  around the mass of sugar.   If bile
is not present, and the test  is carefully conducted in the man-
ner mentioned, the color is not obtained.
  Heller's test is performed by adding to a portion  of urine in
  How may the presence of blood in the urine be detected when the discs are dissolved, as
in purpura? What are urinary casts?  What indications of disease of the kidney do casts
furnish? AVhat is the color of urine containing bile? Describe Pettenkofer's test for bile.
What precaution regarding temperature is to be observed in the use of Pettenkofer's test ?
Describe Heller's test. 
156
TESTS FOR  CHYLE AND SUGAR.
a test tube a little albumen, mixing it w^ell, and then precipi-
tating the albumen Avith nitric acid.  The  coagulum  formed
presents a series of zones  of different colors, red, blue, green,
yelloAV.   The same test may be applied by  adding a drop of
the acid to a few drops  of the urine, placed on a white plate
or saucer; at the line of meeting of the liquids a similar series
of colors is  seen.  Stains of bile  on clothing may lie  distin
guished from pus stains by touching them with nitric acid:  if
it  is bile, the colors are produced;  if it is pus, they fail to ap-
pear.
   The presence of chyle  in urine gives to the fluid a peculiar
milky color which  is almost characteristic, but as it is some-
times absent  or overcome by a stronger tint, it is often neces-
sary to  resort to  chemical tests  to  detect its presence.  In
chylous urine albumen and fat co-exist; if the first is  found,
we may always  suspect  the presence of the second.   Fat  is
easily detected by  adding to some of the urine in a test tube
about one" half its bulk  of sulphuric ether, and mixing them
gently but thoroughly together. Allowing the mixture  to rest
for a few moments, the urine settles to the bottom of the tube,
while the  ether,  containing in  solution  any fat  that may have
been present, floats on its surface.
   The  etherial solution is  to be  removed by a pipette, or by
careful  pouring into a clean watch-glass,  perfectly free from all
greasiness, and allowed to  evaporate.  If the urine contained
fat, it remains on the watch-glass as a stain, formed of minute
globules of oil, the nature of which may be readily proved by
touching or rubbing them with the finger, when they impart to
the glass a characteristic  greasy mark.
   Urine  containing sugar, or  diabetic urine, is usually light
colored, and possesses a very high specific gravity, often reach-
ing 1050 or even 1060.  The  methods for detecting the pres-
ence of sugar are, 1st. Moore's test, which consists in taking a
portion of the urine in a test tube, adding about half its vol-
ume of liquor potassse,  and boiling  the mixture; if  a dark
brown  color  is produced, the presence  of sugar may  be sus-
pected.
   2d. Trommer's test is performed by adding to some urine in
a test tube two or three drops of solution of sulphate of cop-
  How may the presence of bile in stains on clothing be shown ?  What is the color of
chylous urine ? How is the presence of fat determined ? What other ingredient does chyl-
ous urine contain ?  What is diabetic urine ?  What is its color and specific? gravity ?  How
is Moore's test performed ?  How is Trommer's test conducted ? 
THE  FERMENTATION TEST.
157
per.   An amount of liquor potassse equal to the bulk of urine
used is then poured in, and the mixture boiled.   If diabetic
sugar is present, the red suboxide of copper is precipitated; if
there is no sugar, and a sufficient amount of liquor potassse has
been  used, the black oxide  of copper goes doAAm.   Care should
be taken, in employing this test, not to use too great a propor-
tion of sulphate of copper, for, if the quantity of sugar is small,
it Avill not be detected, owing to the fact that the black oxide
formed will completely obscure the red oxide.
   3d. Maumini's test consists in preparing strips of white me-
rino, by dipping them in a strong solution of bichloride of tin,
and drying them in the Avater bath.  A drop of urine  is then
placed on the strip, and it is warmed over a lamp; if the urine
contains sugar, a black spot is formed.
   4th. The fermentation test is the most reliable, for  all the
preceding tests are  at times apt to fail, especially  if the quan-
tity of sugai is minute.   It is performed by taking a bottle or
flask, b, placing in it a teaspoonful of yeast, or more if the quan-
tity of urine to be  used is large; it is then nearly filled with
the sample under examination, and well shaken, to diffuse the
yeast throughout the mixture.  The bottle is now completely
filled with urine, and placed  mouth downward in a large cup
or other vessel containing sufficient fluid to prevent the liquid
in the bottle floAving out.                             Fig.ns.
   The apparatus is to be set aside for a day or so
in a warm place; fermentation soon commences if
sugar is present; carbonic acid gas being evolved,
accumulates in the upper  part of the bottle  Avhile
alcohol is contained in the liquid.
   The carbonic acid may be examined by decanting  Ferm^tlto
it into a  smaller vessel, and agitating it Avith lime-    Te8t-
water, when a precipitate of carbonate of lime is formed.   The
alcohol is usually detected without difficulty by its peculiar
odor; but if the quantity  of alcohol is small, and the amount
of liquid large, it may be necessary to distill it, in order to be
satisfied of its presence.
   I have devoted some little space to the fermentation  test, for
it is only resorted to in doubtful cases;  it should therefore be
thoroughly understood.
   Pus, when present, soon forms  a sediment of pus corpuscles,
--------------------------------------*---------------------------------------------
  AVhat precautions are to be observed in the use of Trommer's test ? Describe Maumini's
test.  Describe the fermentation test.  How is the presence of carbonic acid tested ?  What
is the peculiarity of the pus deposit?
 
158
FUNCTIONS  OF THE  LIVER.
which are readily detected by the microscope.  The deposit
may be  distinguished  from that of mucus by the fact that
when the bottle containing the urine is shaken, the precipitate
diffuses equally throughout the liquid if it is pus, but forms
rope-like, stringy masses if it is mucus.  Usually the presence
of pus is supposed to indicate inflammation of some portion of
the urinary tract, but it is to be remembered that in females it
may be derived from disease of the mouth or neck  of the uter-
us or upper part of the vagina, attended by leucorrhcea.   When-
ever, therefore, a sample  of urine is found to  contain pus, an
opinion should never be given until the  sex of the patient is
known.
   The opposite tables will be found by students to be of great
value in examining samples of urine in a rapid and  satisfactory
manner,  since they present the  subject in a  condensed form,
and enable them more quickly to appreciate the difference of
action of all the ingredients of urine with a few simple tests.
 LECTURE XXVIII.

THE  LIVER AND SPLEEN.
Functions of the Liver.—Functions of the Spleen.—Relations of the Liver
                    and Spleen to each other.

  The peculiar province of the liver, until quite recent times,
was supposed to be the separation of bile from the blood; but
we now knoAV that it has  other and equally important func-
tions  to perform.   While discussing the blood, it  was  stated
that the fluid of the hepatic  vein contained sugar, which did
not exist in that of the hepatic artery or portal A^ein.  In addi-
tion, therefore, to the separation of bile, this gland is also  en-
gaged in the  conversion of fat into sugar, in which form the
combustible is more readily oxidized.  Another function per-
formed by the liver is the  production of a  peculiar fat called
cholesterine, which is appropriated  by the nervous system as
an exterior non-conducting covering to the nervous fibres, and
is known as the white substance of Schwann.
  The spleen  belongs to the class of ductless glands, of which *

 How may a pus deposit be distinguished from mucus without  a microscope ?   What pre-
cautions are to be taken in forming an opinion of the origin of a pus deposit in the urine of
females ? What was formerly supposed to be the sole function of the liver ? What change
is impressed on fat during its passage through the liver ?  What is cholesterine ? 
Examination of Liquid Urine.
Color.
Reaction.
Specific
Gravity.
Heat.
N05
Carbonate of Ammonia.
Urea, excess of............
Sugar.......................
Phosphates.................
Albumen...................
Bile.........................
Blood.......................
Chvle.......................
Varies.
   u
   u
   ((
   c c
Brown.

White.
Alkaline.
Varies.
Varies.
High.

Varies.
White precipitate.

Often white precipitate.
Dark precipitate.
White    '>
Effervescence.
Crystals of nitrate.
White precipitate.
Colored
Dark
White
Crystals with oxalic acid.
Moore's and Trommer's—Fermentation.
Precipitate with heat; soluble in nitric acid.
Bichloride of mercury, etc.
Pettenkofer's and Heller's.
Microscope  and iron test.
Separation of fat by ether.
Examination of Urinary Deposits.
	Color.	Heat.	(IIC1).	(NO;).	Other Tests and Remarks.
Urate of Ammonia...	AVhite or light red. White. u Red. Yellow. Cloudy. Red. AVhite.	Soluble. Insoluble. k ti u <( «(	Soluble. u << Insoluble. u a a	Soluble in strong acid. Insoluble.	Reprecipitates when solution is cool. Reprecipitates by adding (NII3) ; gelatinous. Repreci])itatcs by adding (NH3); granular. Murexide test. Deposit mixes on shaking the vessel; microscope. Deposit does not mix. Albumen in fluid ; discs; microscope. Soluble in (NH3); deposits hexagonal plates on cooling.
Oxalate of Lime......					
					
					
Blood...................					
					
					
NOi=Nitric Acid.  IICl=Hvdrochloric Acid.  NH3=Ainmonia. 
160
THE FUNCTION OF THE  SPLEEN.
the thyroid gland is another example.   Its function Avas for a
long time unknown, until finally Kolliker advanced the theory
that it assisted in the destruction  of the  dying blood  discs,
forcing them to undergo dissolution, and converting their hse-
matin into the substances which form the  coloring matter of
bile.  In order to throw light on this subject, a series of exper-
iments was  undertaken, and printed by Professor Henry Dra-
per in the New York Journal of Medicine for September, 1858.
The method he employed was to take photographs of the 1 >lood
from the splenic vein, and from vessels in other parts  of the
body, and, counting the proportion of  perfect and imperfect
discs in each, obtain  accurate data from which the action of
the spleen could be determined.
   As the function of the spleen  is of considerable importance,
we quote from the paper in question  freely, regarding it as
proving beyond a doubt the truth of the views of Kolliker.
   " The animal chosen was the frog {Rana esculentd).   He is
readily accessible,  and the various  kinds of blood can be ob-
tained without much trouble  by  a careful  dissection.  His
great advantage is the large size of his blood-cells, rendering it
comparatively easy to see the changes occurring in them.   The
blood was photographed dry; 1st, because, from  the result of
several experiments, it did not seem to make any change either
in the form or arrangement of the  cells; and, 2d, to aAToid the
complications incident on the use of suspensory solutions.
   " The plan of procedure was to take a frog and submit him
to the  operation of water at 150° Fahrenheit.  This produces
a species of tetanus suitable for  the dissector's purpose, for all
visible motion, except that of the heart, ceases.  Then, the ani-
mal being stretched on a board  and secured, a longitudinal in-
cision was made at-one  side of the median line, to avoid the
large vessels Avhich lie in that line.   The incision  being carried
through  the abdominal walls, the  intestines  were carefully
drawn out, and Avith them the spleen.  A piece of white card-
board was then introduced underneath, in order to show  plain-
ly the course of the vessels.
   " Up to this time it was not necessary to lose more than a
single drop  of blood in the dissection.  The vessels being then
plainly seen, the peritoneum was cut away, so that the  spleen
was retained in place only by them.   The artery, being dis-
cerned, was seized by a pair of forceps, and  cut on  the side
nearest the  heart; then immediately after the veins were sev-
What was Kolliker's theory regarding the function of the spleen ? 
THE FUNCTION OF THE  SPLEEN.
161
ered, and the spleen being put on a  slip of glass, a drop  of
blood was allowed to spread itself thereon, the artery having
all the while been retained closed.  These drops were dried in
the open air, and were submitted to a power of about 250  di-
ameters, and photographed on glass.
   " For the investigation of the functions of a gland, there is,
of course, no plan so sure to be successful as an examination of
the change it has induced in the fluid passing through it, and
substantiating  such an examination by an analysis of the pro-
duced secretion or excretion.
   " In this gland, however, where no duct exists, and where the
guidance of the secretion is lost, we are necessitated to examine
the passing blood  with double care,  and, noting  its changes,
draw from them the requisite information.
   " The essential object, then, of these  experiments was to pro-
cure blood-cells from the  splenic  artery or other general sys-
temic source, and also from the splenic vein.  The blood from
the artery or system generally represented, of course, blood as
yet unchanged  by the spleen, and that from the A7ein, blood at
a  maximum of change having just passed through that gland.
A number of photographs of each kind were then taken, and
one set compared Avith the other in various ways, and their dif-
ferences noted.   A  choice was made at random from the tables
of differences thus produced, and the conclusions at the end  of
this paper were drawn.
   " At first, attention had to be directed to the relative anatomy
of the splenic vessels of the frog.   Injections of the arteries  of
his abdominal viscera are very difficult to make, because, as the
vessels are small, a fine injection must  be used, and the capilla-
ries on the intestinal walls are so large, that, before all the  ar-
teries are full, some of the veins will be-pretty well injected,
and a dissection subsequent to the injection would be very de-
ceptive.   The only plan suitable under these circumstances  is,
after having drawn out the intestines  and exposed the spleen
on card-board, to inject and carefully observe how the  vessels
are filled.  Of  course, if in several cases  one  of those going  to
the spleen fills immediately, and the rest, after some time, begin
gradually to be colored from the intestine toward the  spleen,
it is justifiable to say that  the first filled is the artery, and the
others the ATeins.
   " The next point was to secure specimens from various frogs,
and, having dried, to label them.
   " The operation Avhich succeeded, namely, photographing the 
162
THE FUNCTION OF THE SPLEEN.
microscopic image, Avas by far the most difficult to perform suc-
cessfully.   It consisted of managing the microscope, of photo-
graphing the image on glass, and of transferring it by chloride
of silver to paper.  The method of illumination, and the focus-
ing of the microscope, are only to be obtained by experience.
In fact, these and the photography have left me but a small
part of thfee  summers.  The  difficulties of photography can
only be known to those who have attempted it.   A good neg-
ative is for long and long
              ''' Rara avis in terris, nigroque simillima cygno'
to the  amateur^
  " There will be presented in this paper  results from the
blood of the splenic veins of four different frogs, of the splenic
artery of one, of the amputated legs of two, and of the  vena
cava of another batrachian, the toad;  the four last being taken
as general systemic blood.
  " In a printed abstract, it is, of course, well-nigh impossible to
introduce photographs for illustration, as was done in the orig-
inal thesis, now deposited in the  Archives of the University
Medical College; and wood-cuts  executed from those pictures
Avould be worth nothing, for the value of photographs turns on
the fact that they are produced (it might be said) without the
intervention of human art,  and are copies of microscopic im-
ages executed  by the  sun, not  having passed through the
draughtsman's  and the  engraver's hands, each of whom intro-
duces in his work necessarily some inaccuracies, which are fatal
to the  comparative trial that these cuts would have to endure.
  " We must therefore content ourselves with simply producing
and examining the tables deduced from those photographs, re-
ferring any one who takes an interest in the matter to the orig-
inals.
  "In the blood of the splenic vein, of 100 cells, 85 were distort-
ed and broken, while only 14 were perfect. ^Theperfect were
therefore to the imperfect as  1 to 6.   In the blood of the ampu-
tated leg, which is  a fair representative of general systemic
blood,  of 140 cells, 68 were perfect, and  67 distorted and bro-
ken.   The perfect were  to the imperfect asltol.  And Avhat
renders it more striking is, that of all the specimens of general
blood that will be introduced, this one has the largest propor-
tion of imperfect cells.
  " In  the following table,  from  which the  above facts were
  What is the proportion of perfect to imperfect cells in the blood of the splenic vein?  How
does it compare with the proportion in systemic blood ?
/ 
THE  FUNCTION OF THE SPLEEN.
163
drawn, the cells called perfect are those AAThich are of an eclip-
tic shajDe, and whose nucleus is central.
Table I.
	Where from.	Perfect.	Distorted and broken.	Total.	Perfect to Imperfect.
Fig. 4 Fig. 5	Amputated Leg..	14 68	85 67	100 140	1 to 6 1 to 1
   " It will be observed that the column marked Total does not
correspond with the total of the two columns marked Perfect,
aftd Distorted and Broken.   This is owing to the fact that the
three columns are produced by three separate countings from
the photograph, and not by a process of addition and  subtrac-
tion, as tables often are.   The deficit consists of cells so nearly
perfect, that in counting they are passed over as  being neither
perfect  nor imperfect.
   " The photograph corresponding to Fig. 4  contains besides
tAvo other  interesting objects.  The first is one of those bodies
knoAvn as  blood-corpuscle-holding  cells, and consists of a sac
Avhose section is about four times  the size of that of an ordi-
nary  blood-cell, and which  seems to contain  in  its substance
four nuclei, each with a semi-developed  or half disintegrated
cell wall.  It is the only one that has come under my  notice
at any time.
   " The second object of interest is a blood-cell  which appar-
ently incloses a crystal; but, upon  a very careful examination
of the  original preparation at different foci, this was demon-
strated to be merely an optical deception, produced by a wrin-
kle in the cell wall.
   "No note is  taken of chyle corpuscles  and free  nuclei.
There seems to be, as a general rule, from four to ten per cent.
of them in all the kinds  of blood that have been  used for spec-
imens in this thesis.
   " Before going farther, it  is well  to create a standard of the
perfect  and imperfect cells in general systemic blood.  By de-
ductions from the following table, Ave shall show that  of every
5 cells of systemic blood, 2 are imperfect and 3 perfect.
   " This proportion seems extremely high for the  distorted and
broken  cells.   By leaving out Figure 5, Ave could lower it to 4
in 13; but it is better to allow it to remain,'high as it is; for,
although the imperfect may be, and probably are, considerably
less in number, still, if we can establish the  fact that  average
splenic blood (venous) contains a greater number of imperfect 
164            THE FUNCTION OF THE  SPLEEN.

cells than this, such a difference will be all the more striking
when the average systemic proportion is lowered.
  " The results that are now introduced are from pictures of
blood procured from the amputated legs of another frog, from
the splenic artery, and from the vena cava of an analogous
batrachian, the toad.
                          Table II.
	Where from.	Perfect.	Distorted and broken.	Total.	Perfect to Imperfect.
Fig. 5 Fig. 6 Fig. 7 Fig. 8		68 73 86 68	67 56 39 5	140 137 126 73	1 to 1 4 to 3 2 to 1 13 to 1
	Toad's Vena Cava__				
	Total.................	295	167	476	3 to 2
					
  "We shall now examine tables from  several specimens of
splenic venous blood, and from them shall demonstrate that of
every 6 cells from the splenic vein, 5 are imperfect.
  " The reason that so large a number as nine figures are used
is because it is much more important to get a fair average pro-
portion than in the former case; for any one can see systemic
frog  blood;  not so with that from the splenic vein.
Table III.
| Perfect.		Distorted and broken.	Total.	Perfect to Imperfect.
Fig. 4	14	85	100	1 to 6
Fig. 9	15	82	97	1 to h\
Fig. 10	17	101	120	1 to 6
Fig. 11	3	50	53	1 to 16
Fig. 12	10	67	81	1 to' 6i
Fig. 13	13	103	120	1 to 8
Fig. 14	24	102	127	1 to 4
Fig. 15	23	74	97	1 to 3
Fig. 16	30	75	110	1 to 2i 1 to 5
	.....149	739		
  "The photograph corresponding to Fig. 10 shoAvs, as Avell as
can be, all the characteristics of splenic venous blood.  There
are in it perfect cells, swollen  cells, stretched cells, cells with
a piece broken out, cells with a part of their contents removed,
empty cells of a chlorotic appearance, broken cells with the nu-
clei near the edge, relics of cell walls, free nuclei.  Is the spleen
creating or destroying ?
  " Comparing now the results  of Table II. with those of Ta-
ble III., we see that in the former,  of every 5 cells, 2 were im-
perfect,  and in the latter, of every 6 cells, 5 were imperfect.
Reducing to a percentage, we find  of imperfect cells—in the
systemic blood 40 per cent.; in splenic vein blood, 83 per  cent.
  " The  conclusion, then, is  plain.  The number of imperfect 
THE FUNCTION OF THE SPLEEN.
165
cells in splenic vein blood is double the general systemic aver-
age.
  " We may also, by a careful examination, perceiA^e that the
progress of destruction is first a tendency to loss of form, then
a decrease of the poAver of impeding light, caused either by
change  of color or diminution of the contained fluid, then a
rupture of the  cell  wall, either from swelling or from some
chemical change in it; finally, the  escape of the nucleus, and
complete solution of the  cell wall.   Not that this is always the
case, for many cells seem to break down at once.
  " But, let the change be AAmat it may, it can only be partially
accomplished in the  spleen, else how is it that we see so many
coming out distorted and decaying ?
  "The most natural conclusion is, that blood-cells coming
here, after having made the tour of the circulation several times,
have such a change Avrought, either in themselves, directly or
indirectly, by means of the plasma Avhich contains them, that
their walls become  no longer capable of resisting the weak
mechanical forces  to Avhich they are  subjected.  Perhaps  the
fibrinous Avail changes like the fibrin of muscles, and becomes
inosite and creatine; the inosite passing on  to complete oxida-
tion in the lungs with its kindred liver sugar, or becoming liv-
er sugar.   As for the rest of the cell, the fat of the nucleus be-
comes liver fat, or bile fat, or liver sugar, the haBmatin colors
the bile, and the globulin  becomes casein, or some  analogous
body.
  " Some  of those cells  which have  passed apparently safely
through may perhaps carry the elements of change impressed
upon them, and in this Avay Ave might account for the distor-
tions in general blood.
  " That such an action  as I haAe described may take place in
the cell wall in passing  through the  spleen is easy to believe
from a very casual view  of the structure of  that organ.
  "Finally, the great conclusion arrived at  is, that as  it is
proved that the splenic vein blood contains  at least double the
general average of imperfect cells, the spleen must be cm organ
for the disintegration of blood-cells."
  Accepting the statement of  Kolliker, that  the function of the
spleen is to destroy the  old, almost worn-out discs, which can
no longer perform in a proper manner the function of carrying
oxygen, it becomes a matter of interest to examine the relations
of the spleen and liver to each other.
  In bile, the coloring matter  is found to contain the iron that 
166                 THE NERVOUS SYSTEM.
entered into the composition of the haBmatin  of the  discs; in
the spleen, discs are disintegrated and broken up. . The relation
of the organs  to each other, therefore, seems to be, that the
spleen destroys the discs, and  the materials produced are fil-
tered out from the blood by the liver, so that it becomes the
duct of the spleen.
  In review, we  may sum up the functions  of these glands as
follows:
  The spleen destroys discs.
  The liver filters out the materials formed by the disintegra-
tion of discs.
  It also converts  fat into  sugar, and produces cholesterine,
which forms the non-conducting envelope of nerve fibre.
                    LECTURE XXIX.
                  THE NERVOUS  SYSTEM.
Phosphorus the special Ingredient of Nervous Substance.—Production of
  Nervous Force.— Gray and white Nervous Substance.—The Ganglia de-
  scribed.— The Nerves described.—Divisions of the Nervous Mechanism.
  —The Nervous Systems of the Lower Animals.—The Sympathetic Sys-
  tem.—The Cerebro-spincd System.—The Brain.—The Spinal Cord.—
  The Nerves.
  Having completed the examination of the organs of locomo-
tion, nutrition, and excretion, we now pass to the study of the
nervous system, which regulates and controls their action.   The
peculiar element of nervous tissue is  a phosphorized oil or fat,
the amount of uncombined phosphorus in which determines in
part its  intellectual power, as is shown in the following table,
in which the brain of an idiot contained about the same pro-
portion of phosphorus as that  of an  infant, while the greatest
proportion is found in that of the adult.
                         From L'Heretier.
	Brain of Infant.	Of Youth.	Of Adult.	Of Age.	of Idiot.
	8-	165	18-	ro-	8-5
  That nervous force is produced by the oxidation of phos-
phorus is demonstrated beyond discussion by the fact that any

  What relation exists between the liver and the spleen ?  What are the functions of the
liver ? What is the function of the nervous tissue ?  What is the special component of
nervous matter ?  How does the proportion of phosphorus in nervous substance vary with
age ?  How is nervous force produced ? 
A'ARIETIES OF NERVE-CELLS.
16:
Fig. 116.
thing AA'hich implies or requires the deArelopment of nervous
force, as continued muscular or mental action, or any powerful
nervous affection, as grief or joy, is folloAved by an increase in
the amount of the phosphates in the urine.
  Of these facts  any one  may satisfy himself by resorting to
the tests given in a previous lecture;  such experiments, how-
ever, are not needed, for all persons must have  noticed the enor-
mous deposits  of phosphates  in the  urine
passed  after hard study, or any severe men-
tal  excitement.
  In order to favor rapid oxidation, and the
immediate removal of the phosphoric acid
produced, all nervous  tissues, but more es-
pecially those Avhich originate  the force, are
freely supplied Avith arterial blood by an ex-
tensive  and intricate  system  of capillary
vessels.
  Nervous tissues are  composed  of tAvo
kinds of materials: 1st. The gray or origin-
ating substance;  2d. The white or conduct-
ing  substance.   Gray  nervous matter con-
sists chiefly of cells, which may be regarded
as being analogous to the cells of an ordinary
Voltaic battery.
  These  cells  vary in form,  as  is  demon-
strated hj Figs.  116,117, 118.  In the  first
there is only a  single pole to the cell; in the
second  there are two  poles:  such cells  are
therefore  called bipolar  cells; in the third
there are many poles or projecting processes:
such cells are consequently called multipolar.
Though there  is  so great a A^ariation in the
figure and number of poles attached to nerve-
cells, they are all constructed of the same ma-
terials, viz., an exterior envelope, AAmich is filled
with a granular  substance, composed to a
great extent of the phosphorized oil or  fat
previously mentioned.
  In order to  construct  a nervous centre, a
number of nerve-cells unite, their projecting
Nerve-cells, 350 Diameters.

      Fig. 117.
Bipolar Nerve-cell, 350
   Diameters.
  How is it proved that the oxidation of phosphorus originates nervous force ?  AVhat is
the function of gray and white nervous substance ?  AVhat is the composition of the grav
substance ?  To what part of an electrical apparatus arc they analogous ? 
168              STRUCTURE OF A GANGLION.


                            Fig. 118.
Multipolar Nerve-cell, 200 Diameters.
poles or fibres  interlacing and intertAvining to form  a com-
pound cell or ganglion, Avhich is the counterpart of an  electric
battery.   The ganglia are  very numerous, being scattered all
over the body, but the largest are found in the cranial cavity.
Many of them seem to be endowed with special properties, but
the greatest proportion are engaged in originating the nervous
force, and controlling the rate of waste and repair, and in regu-
                                       lating the vigor of ac-
                                       tion   of the   various
                                       glands, organs,  and tis-
                                    c  sues composing the sys-
                                       tem.
                                         In  the  figure, d  e
                                       represents  the  nerve-
                                       cells and fibres which
                                    a  form the ganglion; a b,
                                       nerves communicating
                                       with other ganglia;  c
                                       c c, branches that have
                                       originated  in the gan-
             Ganglion of a Mouse.               „]' _. „
  From  the  ganglia the nerves take  their origin.  They  are
composed of white nervous substance, arranged in the form of
tubes, covered externally Avith a layer of cholesterine, Avhich is
a non-conductor,  so that the nerve  fibres resemble  in their
structure the wires of an electric combination, with their exte-
rior non-conducting covering of silk.
  The nervous mechanism in man and the higher animals con-
sists of two portions, the sympathetic system and the cerebro-
 How is a ganglion formed ?  AAHiat is the duty of a ganglion ?  Describe the structure of
the nerves.  AVhat are the divisions of the nervous mechanism in man ? 
ADAPTATIONS IN THE NERVOUS SYSTEM.
169
spinal axis.   In the very loAvest forms of animated creatures
the sympathetic system alone exists.
Fig. 120.
Fig. 121.
Fig. 122.
Nervous System of Mollusca.
                               NeWOUS System of Radiata.
                           In molluscs the* ganglia
                         are   scattered  irregularly
                         throughout the body of the
                         animal;  in radiates  they
                         are  arranged  in a  circle
                         around the  mouth;  in ar-
                         ticulates they  are  placed
along the  median line, there being often a pair of
ganglia for each ring composing the creature, and a
single ganglion at each extremity of the nervous sys-
tem.
   Vertebrates possess a spinal cord and brain, which N0efr^°ru^[f^ra
are protected  throughout  their Avhole extent by a
covering of bone, and are frequently brought  into communica-
tion with the sympathetic or ganglionic  system, Avhich is scat-
tered throughout the body, its fibres entering into  all the
glands, being freely distributed to  the muscular coats of the
intestine, and forming a network on the  arteries.
   The conducting fibres of the sympathetic system are smaller
than those of the cerebro-spinal axis;  they also contain a num-
ber of nucleated cells.
   In the following figure the distribution of the sympathetic
nerve to the various  organs is shown, together Avith some of
the large ganglia connected Avith it: 1, the eye-ball;  2, branch
of inferior oblique; 3, branches of tri-facial; 4, ophthalmic gan-
glion ; 5, spheno-palatine ;  6,  otic;  7, submaxillary and, 8, sub-
lingual ganglia;  9, ex motor oculi nerve;  10, facial; 11, glosso-
pharyngeal; 12, right pneumogastric; 13, left pneumogastric ;
14, spinal; 15, hypoglossal;  16, cervical plexus; 17, brachial
  What is the lowest form of nervous mechanism ?  How are the ganglia arranged in mol-
luscs—in radiates—in articulates ? AAHiere is the sympathetic ? Does it communicate with
the cerebro-spinal system ?  What are the peculiarities of the fibres of the sympathetic ? 
170
THE  SYMPATHETIC SYSTEM.
                              plexus;  18, intercostal nerves ;
                              19, lumbar plexus ; 20, sacral
                              plexus;  21, superior cervical
                              ganglion; 22, Jacobson's nerve;
                              23, carotid branch of vidian; 24,
                              external motor oculi; 25, oph-
                              thalmic  ganglion; 26, branch
                              to pituitary body; 27, anasto-
                              mosis of cervical ganglion with
                              first  cervical nerves;  28, caro-
                              tid  branches; 29, pharyngeal
                              plexus;  30, laryngeal branch;
                              31,  superior cardiac  branch;
                              32, nerves of  union  of upper
                              cervical with, 33, middle cervi-
                              cal ganglion;  34, anastomotic
                              nerve; 35,recurrent; 36,mid-
                              dle  cardiac;  37, junction  of
                              middle cervical and, 38, inferi-
                              or cervical ganglia; 39, branch-
                              es to great ATessels; 40, branch-
                              es to subclavian and ATertebral
                              arteries; 41,branch to first in-
                              tercostal ; 42,  cardiac ganglion
                              and  its plexus ; 43,44, plexus-
                              es of right  and left  coronary
                              arteries; from 45 to  46, thora-
                              cic  ganglia; 47,  the  splanch-
                              nic;  48, semilunar ganglion;
                              49, lesser splanchnic; 50, solar
                              plexus;  51,pneumogastric; 52,
                              phrenic; 53, gastric  coronary,
                              54, hepatic; 55,  splenic;  56,
                              superior mesenteric ;  57, renal
                              plexus; 58  to 58,lumbar gan-
glia;  59,lumbo-aortic  plexus; 60,61, enlargements  of aortic
plexus; 62, spermatic  plexus;  63, inferior mesenteric plexus;
64, hypogastric plexus ; 65 to 65,^sacral ganglia;  66, coccygeal
ganglion ; A, heart, showing cardiac  plexus ; B, arch  of aorta;
C, innominata; D, subclavian;  E, inferior thyroid; F, external
carotid;  Gr, internal carotid; H,  thoracic aorta;  I, abdominal
aorta; J, primitive iliac;  K, intercostals; L, pulmonary artery;
M, vena cava descendens ;  N, vena cava ascendens;  O, pulmo-
The Sympathetic System. 
THE  CEREBRO-SPINAL  SYSTEM.
171
nary veins; a, lachrymal gland ; b, sublingual;  c, submaxillary-
gland;  d, thyroid gland; e, trachea; f oesophagus; g, stomach;
h, small intestine;  *, colon; j, sigmoid flexure;  h, rectum; I,
bladder;  m, ureter;  n, prostate gland; o, seminal vesicles; p,
vas deferens; q, spermatic cord; r, diaphragm.
  The sympathetic is the nerve of organic life.   It takes charge
of digestion, absorption, and circulation; regulates the rate at
which the secretions of the glands are produced, and attends
to the processes of nutrition, repair, and excretion.  When the
cerebro-spinal axis is at rest, the great sympathetic is busy re-
pairing the Avear and loss which the muscular and other tissues
have undergone in the production of motion or action.  It su-
perintends  the  vegetative  life of the animal, and is never at
rest.
  The cerebro-spinal system consists of the brain and the spi-
nal cord and nerves; through it all the manifestations of ani-
mal life are originated  and conveyed.  It regulates  the move-
ments  of the  voluntary muscles, presides over the  special
senses, and furnishes the thought, ideas, and will, which have
enabled man almost to  annihilate time and space.
   The  brain is placed in  the cranial cavity'; its  weight  is
equal to about  ■£%th of the total Aveight of the  body.  It is di-
vided  into two distinct por-
tions, the cerebrum, or greater
brain, which is aboAre, and  the
cerebellum,  or  lesser  brain,
Avhich lies beneath the poste-
rior part of the  cerebrum, as is
sIioavii in Fig. 124, in which  1 6
is the medulla oblongata; 2, ^
pons varolii;  3,  cerebellum; 4,
pneumogastric lobule;  5, fron-
tal convolutions; 6, parietal
convolutions; 7, occipital con-
volutions; 8,fissure of Sylvius;
9,9, its branches.
   The  cerebrum presents exteriorly a  surface  marked Avith
curved pojections called the convolutions.  On making a sec-
tion of the  organ, Ave find that the interior portion is composed
of Avhite  or conducting nervous tissue, outside of Avhich there
  AVhat is the function of the sympathetic ? Does it rest during sleep?  What is the func-
tion of the cerebro-spinal system ?   What parts compose the cerebro-spinal system ?  What
is the weight  of the brain?  AVhat are the divisions of the brain?  AArhat are the convolu-
tions of the cerebrum ?  Is the gray or the white substance on the exterior in the cerebrum?
 
172           THE BRAIN AND  ITS  MEMBRANES.
Fig. 125.                          Ficr. 126.
The Cerebrum.
is  a layer of gray origina-
ting material.   By throw-
ing the external gray lay-
er into folds and convolu-
, .                     n              Section of the Cerebrum.
tions, an enormous surface
h gained, on Avhich innumerable blood-vessels form a sheet of
interlacing capillaries.
   The membranes of the brain are three in number:  1st. The
blood-vessel layer, mentioned above, which dips down into the
spaces between the convolutions, to supply the gray substance
freely Avith blood:  it  is called  the pia mater; 2d. A  serous
membrane, which passes over the convolutions, but does not
enter the depressions.  Like other serous membranes, it forms a
sac and contains fluid, so that the brain rests  on a Avater cush-
ion, Avhich protects it from violence, and equalizes pressure : it
is called the  arachnoid.  The third membrane nourishes the
bones of the cranial cavity, and is called the dura mater ;  it is,
in reality, the periosteum of the cranial bones.
   The cerebrum is divided laterally into two parts, called the
right and left hemispheres, each of Avhich is subdivided into  an
anterior, middle, and posterior lobe.   From the base of the cer-
ebrum, on each side of the median line, the cranial nerves take
their  origin, and pass  to the various organs with Avhich they
are connected.
  What is gained by the convolutions into which the gray matter is thrown ?  AVhat are the
membranes of the brain?  Describe the pia mater.  What is the arachnoid? Describe the
dura mater.  AVhat are the subdivisions of the cerebrum ? Where do the cranial nerves
take their origin ?
 
THE  DIA'ISIONS OF THE BRAIN.
173
Base of the Brain.
  In  Fig. 127, a is the
anterior  lobe; c,  middle
lobes; g, posterior lobes;
/', longitudinal fissure;  y,
y, fissure of  Sylvius;  t,
the optic chiasm; z, cor-
pora  albicantia;  d, the
pons  A^arolii;  e,  the me-
dulla oblongata; n, spi-
nal cord; 1, the olfactory
bulbs and nerves;  2, the
optic; 3, motor oculi; 4,
pathetic ; 5, tri-facial;  6,
external motor oculi; 7,
portio dura  and mollis;
8, pneumogastric, glosso-
pharyngeal, and spinal ac-
cessory ; 9, hypoglossal.
   Many  of  the  cranial
nerves, as the optic, arise
from distinct ganglia; we
may  therefore regard  the  cerebrum as being composed  of a
number  of ganglia, Avhich possess special functions.
   The cerebellum consists of
parallel  plates, and is  covered
by the membranes of the brain.
From it columns  of  nervous
substance  pass, to  unite  Avith
other similar  columns from the
cerel >rum, to form the  medulla
oblongata, Avhich is connected
Avith all the  great ganglia at
the  base of the  brain, and is
the commencement of the spinal cord.
   The spinal cord is placed m the vertebral column, and term-
inates beloAV in the canal of the sacrum, by dividing into  a
number  of branches, called the  cauda  equina.   The shape of
the cord varies, as is shown in the folloAving figure, Avhich rep-
resents sections of different portions.   On examining such sec-
tions, Ave find that the bulk of the spinal cord is composed of
white nervous substance, arranged in six columns, an anterior,
The Cerebellum.
 AVhat is the composition of the cerebellum?
cerebrum?  AVhat is the medulla oblongata?
white substance of the cord arranged ?
How is the cerebellum connected with the
AVhat is the cauda equina ? How is the 
174
THE SPINAL  CORD AND NERVES.
Fig. 129.
®
sections of Spinal Cord.
                                  middle, and posterior col-
                                  umn on each side.  These
                                  inclose a certain portion
                                  of gray  substance, Avhich
                                  occupies  the  central  re-
                                  gions  of the cord.  The
                                  proportion  of gray mate-
                                  rial  varies, as is shown in
                                  the  sections in Fig. 129.
                                     Exteriorly  the  spinal
                                  cord is covered by a series
                                  of membranes similar to
                                  those of the brain, and of
                                  Avhich they  may  be  re-
                                  garded as  continuations.
                                  The first  membrane is
                                  composed  of the  blood-
                                  Aressels which nourish the
                                  organ; the second affords
                                  protection; and the third
                                  is analogous  to  the  dura
mater.  From the anterior and posterior columns of the cord
the nerves of the body take  their origin; they  are all formed
of white  nervous substance, and convey impressions to  and
from the nervous centres or ganglia.
  The nerves of the head are  derived directly from the base
of the brain.   Many of them are engaged in special functions,
as the optic, olfactory, and auditory, while others are distrib-
uted to the muscles and skin of this region.  The nerve which
supplies the  facial muscles is called the  facial;  it passes over
the masseter  muscle, and is the chief nerve of expression, as is
demonstrated by the blank,  expressionless appearance of one
side of the face when the facial nerve of  that side is injured.
  The nerves of the trunk, upper and lower extremities, are de-
rived from the spinal cord.  They originate in the  anterior
and posterior columns of the  cord, and pass out through foram-
ina between  the vertebrae.   In Fig. 130, a is  the  cervical por-
tion, with its nerves; b, the dorsal portion and nerves; c, the
lumbar portion and nerves;  e, the pons varolii.
  In  the  neck the first four spinal  nerves unite soon  after
emerging from the vertebral column, and form  a  plexus, from
 What are the membranes of the cord?  From what parts of the cord do the nerves take
their origin ?  Describe the facial nerve. Describe the cervical plexus. 
THE  SPINAL CORD AND NERVES.
175
which branches are given to the mus-
cles about the  shoulder.   The  re-
maining four  cervical and first dor-
sal form the  brachial  plexus, from
Avhich the axillary, median, radial,
and ulnar  nerves are derived, and,
passing down the arm in the vicinity
of the arteries, are distributed to the
muscles  of the upper extremity.
   The dorsal spinal nerves pass with
the intercostal arteries in the groove
in the under edge of the rib.  The
sacral nerves unite to form the great
sacral plexus, from which the largest
nerves in the body, called the  sciatic
or ischiatic, are derived.  They pass
down  the  legs,  giving branches  to
the muscles of the lower extremities,
and accompanying  the  arteries  in
their course,  and  bearing the same ,
names.   In addition to the  nerves \l
and plexuses  mentioned there  are
many others, but we must  refer the
reader to the works on anatomy for
their description.
Fig. 130.
         LECTURE XXX.

FUNCTIONS OF THE DIFFERENT PARTS
      OF THE NERVOUS SYSTEM.

Function of the white Substance.—Rapidity
  of the Conveyance of Impressions.—Sim-
  ple Ganglia.—Registering Ganglia.—In-
  fluential Ganglia.—Relations and Func-
  tions of the Nerves, Spinal Cord, Ganglia
  at the Base of the Brain, and of the Cer-*
  ebrum to each other.—Functions  of the'.
  Cerebellum.—Review of the Functions of the Divisions of the Nervous
  Mechanism.
The Spinal Cord.
  Having described, as far as our limited space  permits, the
anatomy of the nervous  system, Ave next pass to the explana-
  Describe the brachial plexus.  How are the ^orsal spinal nerves distributed ?  Where is
the sacral plexus ?  Describe the sciatic nerve. 
176   FUNCTIONS OF THE GRAY AND AVHITE SUBSTANCE.
tion of the functions of the different parts, as far  as they are
understood.
 • It is the province of the AAhite matter to conduct the nervous
force, as is clearly demonstrated by the fact that if we cut  a
nerve all power of motion and sensation are  lost in the parts
supplied by it;  but if to the loAver cut extremity of the nerve
an electric current is properly applied, movements are produced
in the muscles supplied by the nerve, Avhile, if the upper cut
extremity is irritated, pain is felt, Avhich is referred  to the same
muscles  or regions.  The rate of transmission of impressions
along the fibres bears a direct ratio to the temperature of the
animal.   In man it is about 200 feet in a second.
  In a similar manner, we may satisfy ourselATes that the gray
matter originates the force, for if the gray substance of the gan-
glia is destroyed, the power of originating motion is lost, though
the nerves still retain their conducting power unimpaired, as
may be shown by testing them Avith the electric current.
  The ganglia, as has been stated, are composed of gray sub-
stance.   They not only originate the nervous force, but, under
certain circumstances, they also become the repositories of ev-
ery species of nervous manifestation.   In such registering gan-
glia thoughts and impressions are stored away, the previous ex-
istence of Avhich  is  almost forgotten, until by some  incident
they are recalled in all their pristine vigor and clearness.
                  In the  adjoining figure, the relation  of the
                registering ganglion to the  simple ganglion is
                shoAvn;  a and  e are the  poles or  neiwes  con-
                veying impressions to and from the simple gan-
                glion, v, which  is connected by another nerve,
                c, to the registering ganglion, r.   The impres-
                sion brought to the ganglion v by the afferent
                nerve a  is  registered, or in part  retained by
                the ganglion r, which also holds  in reserve  a
part of the force generated in v, and com^eyed along the effer-
ent nerve e to produce  motion in the parts to which a and e
are distributed.
  The fibres  which form a nerve  are  engaged in two distinct
actions: some, like a, are afferent, and convey the impressions
to the  ganglion, while others, like e,  are efferent, and convey
  How is it proved that the nerves convey impressions? AVhat is  the rapidity of convey-
ance of impressions along the nerves in man ?  AVhat determines  the rate of conveyance ?
What is the duty of the gray matter ?  AVhat are registering ganglia ? AAThat is the relation
of the registering to the simple ganglia? Do all the fibres of a nerve convey impressions in
the same direction ?
 
            REGISTERING AND INFLUENTIAL GANGLIA.       177

 the motor force to the muscles.   When Ave irritate the sole of
 the foot of a person who is sleeping, the impression is conveyed
 along the afferent fibres  of the nerve to the  spinal cord, and
 through the efferent fibres the nervous force is sent which is to
 produce movement  in  the muscles  attached  to the irritated
 member.  Such motions  occur without the knowledge of the
 individual, and may be produced in animals in  which the spi-
 nal cord is cut; they are  therefore called reflex  actions.
   It has been stated in a previous paragraph that the spinal
 cord takes its origin in certain ganglia at the base of the brain.
 The relations  of these  to the  cord and nerATes  are similar to
 those shoAvn in Fig. 131.   The nerves are the poles a and e;
 the spinal cord is the simple ganglion v, and the ganglia at the
 base of the brain represent the registering ganglion, r.
    In the diagram, Fig. 132, a more perfect devel-
 opment  is  illustrated.  The registering ganglion
 is divided so that one portion, s, takes charge of
 the sensations, Avhile a second, m, superintends  the
 motions to be  produced.  Another element  has
 also  appeared, the influential ganglion, c c, as it is
 called, Avhich is represented in man by the cere-
 brum.
   Upon the size and development of the cere- rk^^^c
 brum the  position of the individual in the scale InfluentialGangiion.
 of intellect depends, the anterior lobes seeming  to be the  spe-
 cial seat of intellectual power.  Mere bulk is not the only ele-
 ment of size in  the cerebrum, for we must also consider the ex-
 tent of gray matter exposed to the action of blood-vessels.   A
 cerebrum Avhich  has deep fissures betAveen  its convolutions
 possesses more'power than another  which has greater bulk
 but shallow fissures.
  In the Avorks on phrenology the cerebellum is supposed to
 be  the seat of the sexual  passions, but this is  not the case, for
 a large part of the organ  may be destroyed AArithout injury to
 the procreative  power.  The true function of the cerebellum is
 to  co-ordinate the forces Avhich haA^e been created in the gan-
 glia of the brain, and produce regularity in the action of mus-
 cles which are to execute required movements.   That this is
 the true explanation of its function has been  demonstrated in
 Describe the action of the  afferent and the efferent fibres.   What are reflex actions ?
 What is the relation of the spinal cord to the ganglia at the base of the brain ?  What is
 the influential ganglion ?  AA'hat is the relation of the cerebrum to  the ganglia at the base
 of the brain and the cord ? What determines the intellectual power ? Is the cerebellum the
seat of sexual passion ?  What is the  duty of the cerebellum ?
                             M
 
178           REVIEW OF THE  NERATOUS SYSTEM.
the most satisfactory manner by vivisections  on animals, in
which all attempts at motion in a straight line are  destroyed
by injuring certain  parts  of the cerebellum.  An  animal so
treated can only move in a  curved or circular course, and no
longer possesses  the  power  of co-ordinating the action  of its
muscles.
  In order that there may be no obscurity regarding the func-
tions  of the different parts of the nervous system, we restate
them  in a condensed form.
  The  sympathetic  system regulates the processes  of organic
or A^egetative life.
  The cerebro-spinal axis presides over the manifestations of
animal lifa
  The nerves are the channels of communication between the
ganglia, and organs, and tissues, conAreying sensation and action.
  The spinal cord is  a simple ganglion, and can originate mere
reflex actions.
  The ganglia at the base of the brain are the  registering gan-
glia, which also possess the power of originating nervous force.
  The  cerebrum is  the final registering  and influential gan-
glion.
  The cerebellum is the co-ordinating ganglion. It is the bind-
ing-room of the printing-house of the brain, in which the  plates
and pages that have been  formed in the engravers', composi-
tors',  and  press  rooms, or ganglia of the establishment,  are
placed in proper relation to each other, so as to form a book,
Avhich may be boxed up Avith other works taken  from the re-
pository or cerebrum, and sent down the dumb-Avaiter or spi-
nal cord to fill an order received through  the  telegraph  or af-
ferent nerve by the railroad or efferent nerve.
  How is the function of the cerebellum demonstrated ? What is the function of the sym-
pathetic nerve—of the cerebro-spinal system—of the nerves—of the  spinal cord?  What is
the duty of the ganglia at the base of the brain—of the cerebrum—of the cerebellum ? 
DISTRIBUTION  OF NERVES TO THE SKIN.         179
                     LECTURE XXXI.
                   THE SPECIAL  SENSES.
 The  Five  Senses.— The Sense of Touch.—Its Location.—The Skin de-
  scribed.—The Papilla}.—Acuteness of Sensation depends on the number
  of Papilla}.—Sense of Touch corrects that of Vision.—Sense of Touch
  and of Temperature are distinct.—Localization of Touch in Lower Ani-
  mals.

  The  special senses by means of which man is brought in
communication Avith the  external world are five in  number—
Touch, Taste, Smell, Hearing, Vision ;  of these, the  senses of
touch, taste, and smell act by direct contact.  The first is found
in the lowest forms of animals; it is the  simplest in its  con-
struction and method of action; we shall therefore first exam-
ine into the anatomy and physiology of touch.
  This  sense is situated chiefly in the skin, which is composed
of two layers; the exterior is called the cuticle, and is formed
of epithelial cells, which  arise from the lowest portion of the
layer, and gradually become thinner as they are more exterior,
until finally they become  scale-like, and are rubbed off by con-
tact with various substances.
  The function of the  cuticle is to protect the parts lying be-
neath it.  In man and the majority of animals it is protected
against the action of the air, and  kept soft and flexible by a
peculiar oil secreted by special glands;  in  fishes and creatures
Avhich live in the water it is covered by a thick mucilaginous
material Avhich ansAvers the same purpose.
  When  the  cuticle is subjected to continual pressure it be-
comes gradually thickened, as, for example, on the*soles of the
feet, where it  reaches  a  thickness of  an eighth of an  inch.
Sometimes the induration is very small in extent and circum-
scribed, forming corns,  which produce  severe  pain,  not  only
from their own sensitiveness, but by pressing on the nerves of
the cutis  A^era.
  The cutis vera, true skin, or derma, is freely supplied with
  Name the special senses. Which  senses act by direct contact ?  AAHiich is the simplest
sense ?  Describe the external layer of the skin. What is the function of the cuticle ?  How
is the skin enabled to retain its softness and flexibility?  What are corns?  What names
are given to the second layer of the skin ? 
180
SIZE AND  SHAPE OF THE PAPILLAE.
nerves, which terminate in a loop covered by cuticle, forming a
projection called a papilla.   The papillae are scattered all over
the body, but are very numerous in the  fingers, which are in
man the special organs of touch; on them the papillae are ar-
ranged  in rows, which cover the anterior surface of the hand
and fingers.
  The papillae which form the ridges of the tips of the fingers
are about ^th of an inch in diameter, and ^th of an inch in
height.   In form they are conical, as is shoAvn in the following
figures.
        Fig. 133.                          Fig. 134.
Simple Papilla;, 35 Diameters.             Compound Papilla;, 00 Diameters.
  The greater the number of papillae  in any_ part, the greater
is its sensitiveness, as is demonstrated by bringing the points
of a  pair of compasses in contact with the skin of various parts
of the body, when we find that in those parts where the papil-
lae exist in greatest numbers  both the points of the  compass
can be distinguished distinctly when separated by the smallest
interval.  By means of the same device we can readily determ-
ine  the  region of greatest sensitiveness; on the tip  of  the
tongue the points cease to be distinct, and merge into one, when
the interval is reduced to -^jth of an  inch;  on the tip of the
finger the same result is produced when it is TVth; on the lips,
-|th ;  on the tip of the great toe, % an inch;  and the middle of
the thigh, 2| inches.
  By means  of the  papillae two distinct orders of impressions
are  appreciated:  1st. Pressure, which  acts mechanically;  and,
2d. Temperature,  which acts chemically, by producing variation
in the rate of waste and nutrition.
  Through pressure or contact with various  objects the sense
of touch becomes of great importance to the superior sense of
vision, for the latter is to a certain degree educated by the for-
mer  before it reaches perfection.  The eye can of itself determ-
  YVhat are the papillae? What is their size?  How are they arranged on the fingers?
How does the number of papilla? affect the sensitiveness of any part ?  Name the order of
sensitiveness of various parts of the body.  How do pressure and temperature affect the pa-
pillae ? 
             DECEPTION OF THE SENSE OF TOUCH.          181

ine the crude outline of an object, but it can not appreciate so-
lidity  until it has first been  educated by the  sense  of touch.
This fact was demonstrated satisfactorily by the case of Franz,
in Avhich an operation for congenital cataract was performed on
the patient after he  had received  the information usually im-
parted to the blind.   The operation was successful, and the pa-
tient obtained a very fair degree of vision.   On presenting to
him a cube, he  thought it Avas a square; a sphere and a disc-
both appeared to be  circles.  When the objects Avere placed in
his hands he immediately recognized their true figure, and was
surprised at his stupidity in committing  such errors.
   Under certain conditions the sense of touch  is singularly de-
ceived, as, for example, in the experiment of Aristotle, in which
a pea or other small  sphere is rolled under the  tip of the index
and middle fingers.   So long as the fingers are  in their natural
position, the individual has no difficulty in stating  under which
finger-tip the pea is, but when the  fingers are crossed over each
other,  there is often the greatest uncertainty in  the mind of the
experimenter regarding the position of the pea.
   If we pass the tip of one finger over any  surface, Ave can
readily discover Avhether it is flat, convex, or concave; but if
another person  takes hold  of the finger, and passes it  over the
surface, he may deceive us completely regarding its nature.  If
the surface is flat, and he presses the finger more when passing
over the centre  than at the circumference, he will  induce  us to
think  that it is  concave; by pressing less at the centre, it will
be made to appear convex.
   Sometimes sensations which originate in the brain are  refer-
red to the skin of various parts of the body;  these  are  often
very disagreeable and annoying, being likened by the sufferer
to the crawling of ants, or some  such uncomfortable impres-
sion.
   The sense of temperature is distinct from that of contact, or
true touch, as is demonstrated by the fact that  in paralysis the
first is often destroyed, while the second remains;  and the un-
fortunate individual, having lost the appreciation of the vicinity
of hot substances, is  sooner or later severely burnt.
   In appreciating temperature, the skin  acts more like a calo-
rimeter than a thermometer, measuring rather the quantity than
  How does the sense of touch correct that of vision ?  Relate the case  of Franz.  Under
what circumstances may the sense of touch be deceived ? Can sensations affecting the or-
gan of touch originate  in the brain ?  How is it demonstrated that the sense of touch and
that of temperature are distinct ?  Does the skin measure the intensity of the temperature
only? 
182
THE  TONGUE DESCRIBED.
the intensity of the heat to AArhich it is exposed.   Of this any
one may satisfy himself by placing his finger in a vessel of hot
water, and then immersing the whole hand.  The intensity of
the heat seems in the latter instance to be far greater, yet we
know that it is the same in both cases.   Appreciation of tem-
perature by the skin is therefore very uncertain, unless we take
into account the extent of surface exposed.
  In many animals the sense of touch is specially developed in
some part of the body.  In the hog it is in the snout;  in the
elephant, in the trunk; in  insects it is usually  in the palpi,
near the antennae, or feelers.
                     LECTURE XXXII.

                       TASTE AND SMELL.

 Tissues composing the Tongue.—Sensations appreciated by it.— The Pa-
  pillce described.—Distribidion of the Senses of Touch and Taste on the Or-
  gan.—Action of the Papillce under the Influence of strong Flavors.—
  Deception of the Organ of Taste.—Location of the Sense of Smell.—Di-
  visions of the Nasal Cavity.—Distribidion of the Olfactory Nerve.—
  Conditions essential to the proper Action of the Sense of Smell.—Inverse
  or subjective Sensations.

   The sense of taste is placed in the buccal cavity, and is situ-
 ated in the tongue, and not  in the palate.
   The tongue is  composed  of muscles, which are covered by
 mucous membrane, and freely supplied with blood-vessels  and
 nerves; it is consequently capable of a great variety of move-
 ments, assisting in the production of certain  sounds called Un-
 guals, and by its sensitiveness enabling us  to select those arti-
 cles of food which are suited to the wants of the system.
   The tongue is capable of three distinct classes of sensation,
 viz., touch, temperature, and taste.   The first and second are
.most  acute  at the tip, and gradually fade aAvay toward the
 base, while the sense of taste is dull at the tip, and acute at the
 base of the organ.
   The papillae of the  tongue are of two classes, some being
 small and others large.  The first are most numerous at the tip,
 and are the papillae  of touch, while the large papillae, in which

  Mention the special location of the sense of touch in some of the lower animals. Where
 is the sense of taste located?  What tissues compose the tongue? What are the three sen-
 sations appreciated by the tongue ? How are the senses of touch and taste distributed on the
 tongue ? Describe the papillae of the tongue.
4 
ACTION OF THE PAPILLAE OF THE TONGUE.      183
the gustatory nerve, or neiwe of taste, com-
mences, are found at the base of the organ
in the greatest numbers.
   In order that any substance should affect
the sense of taste, it must be soluble in sal-
iva ; all bodies  insoluble in that fluid are
tasteless.   Salt, by increasing the solubility
of various  materials,  renders  them more
gratifying to the  palate;  it is therefore
highly prized as a condiment, together with
many other articles, as pepper, mustard, etc.
   Under the influence of strong flavors like
vinegar, the papillae change their figure, be-
coming elongated and pointed; it is there-
fore probable  that the  sensation  of taste
may be produced by the tension to which the nerves are sub-
jected.
   The sense of taste is intimately connected with that of smell,
as is demonstrated by the fact that many substances lose their
taste when the nostrils are closed; but this is by no means
the case always, for there are many articles, like quinine, Avhich
affect the sense of taste powerfully, but are without any action
on that of smell.
   As the sense of touch may at times be subjected to decep-
tion, so that of taste may also be easily deceived.  A smart,
quick blow delivered on the tongue gives the impression of a
strong flavor; an  electric  current produces  a metallic  taste;
and a jet of air throAvn on the tongue gives a sensation similar
to that produced by saltpetre.   Impressions which originate in
a disordered condition of  the brain will also produce impres-
sions similar to those caused by flavors, being sometimes pleas-
ant, but usually disagreeable.
   Temperature possesses considerable influence over taste.  A
very hot  or a very cold liquid taken into the mouth seems to
affect the papillae  so profoundly that some few seconds must
elapse before they regain their power.

                            SMELL.
   The sense  of smell is situated in the nasal cavity, which is
  What condition is essential in order that a substance should affect the organ of taste?
How does salt affect the flavor of articles of food?  How do strong flavors like vinegar af-
fect the papillae ?  Does the same  substance always affect the organ of taste and that of
smell?  What impressions may deceive the sense of taste?  How does temperature affect
the sense of taste ?  AVhere is the sense of smell situated ?
 
184
THE  SENSE OF SMELL.
Fig. 136.
Distribution of Olfactory
  on Septum of Nose.
Distribution of Olfactory
 on outer Wall of Nasal
 Cavity.
                         divided by the vomer into two lateral
                         portions, each of which is subdivided
                         by the turbinated bones into a  supe-
                         rior, middle, and inferior meatus.   The
                         sides of the cavity, and the thin, scroll-
                         like plates of the turbinated bones, are
                         covered by mucous membrane,  called
                         the  Schneiderian  membrane.   To  it
                         the nerve of smell, or olfactory, is dis-
                         tributed,  the greatest portion of the
                                nerve  passing  to  the  upper
                                meatus, so that when the odor
                                is feeble or delicate, the air is
                                drawn in strongly, to carry the
                                odoriferous particles  into the
                                upper part of the cavity.
                                  In  order  that  substances
                                should  affect the organ  of
                                smell, they must be capable of
assuming either the vaporous condition, or such a fine degree
of subdivision as to be readily draAvti in by the currents of air
introduced during respiration.   The conveyance of odoriferous
particles by currents of air precludes the necessity of mobility
in the organ  of smell;  it is therefore stationary in nearly all
animals.
  The senses  of taste and  smell are confined in  their action
Avhen compared with those of hearing and vision.   The  eye
can at a glance perceive a host  of objects; the ear can detect
many sounds; but the  sense  of smell can appreciate but one
odor at once, failing to discover those which are  feeble, if at
the same time one Avhich is powerful is present.
  The special function  of the sense of smell  is to enable  ani-
mals to discover the presence of substances suitable for food.
The carnivora, in  whom the turbinated bones are wonderfully
extended and  intricate, affording  a very large surface for the
distribution of the olfactory nerve, can discover the presence
of food which is  hidden from sight.   The herbivora will in
pasturing,  select out the tender  blades of grass, and  avoid all
offensive weeds, by the aid of this sense.
  In reptiles it is developed to  a  very slight extent; in birds
  What are the divisions of the nasal cavity?  Give the name of the mucous membrane of
the nasal cavity. What is the name of the nerve of smell ? To which meatus is it chiefly
distributed ? What condition is essential in order that substances should affect the organ of
smell ? What is the object of the sense of smell ? 
             INVERSE OR SUBJECTIVE IMPRESSIONS.         185

it is more perfect; but even the carnivorous birds do not depend
upon it to discover their food, as was shoAvn by Audubon, Avho
stuffed the skin of a donkey with straAA*, and hid the carcass of
the animal under leaves in a ditch in the ATicinity, Avhen he
found that the  buzzards quickly discovered the stuffed skin,
but failed to find the highly-odoriferous carcass.
  The sense of smell is developed to the highest degree in the
carnivora, but yet there  are  peculiarities connected with  it
which are very singular.   A dog, that can without difficulty
discover his master in a dense crowd, or follow him for a great
distance by the odor of his footsteps, seems to take no notice
of the perfume  evolved by a rose, Avhile any of the herbivora
Avould perceive it instantly.
  Among the numerous substances AAmich the fashionable peo-
ple of all nations  have adopted as luxuries, none are more ex-
traordinary than those employed as perfumes.  Ladies are dis-
gusted by the man who indulges in chewing tobacco;  but
what is to be said of the apparently delicate, refined woman,
who renders her presence insufferable by the use on her person
of fashionable perfumes, derived from intestinal or other secre-
tions  of certain animals ?
  As was the case Avith the  senses of touch and taste, so the
sense of smell may annoy an individual with odors which have
no  real existence, but are imaginary^ being the product of his
own disordered nervous system.   To these phenomena the des-
ignation of inverse or subjective sensations are given, and Ave
shall find that they exist in connection with the senses of hear-
ing and vision as well as Avith touch, taste, and smell.
                    LECTURE XXXIII.

                  PROPERTIES  OF  SOUND.

 General Properties of Waves.—Reflection and Interference of Waves.—
  Nature of Sound.—Analogy of Sound Waves  to Water Waves.—Ac-
  tion of the Ear Trumpet.— Velocity of the Passage of Sound in various
  Media.—Effect of Variation of Density of Air on Velocity of Sound,
  —Non-conducting Poicer of Inelastic  Bodies.—The Pitch and Quality
  of Notes.

  The  ear is the organ of time, and determines the rapidity
Avith which sounds succeed each other.   It is very complex in
  Do the carnivorous birds hunt by sight or smell ?  In what class of animals is the sense
of smell developed to the highest degree ? What are inverse or subjective sensations ? 
186
PROPERTIES of avaves.
its construction, and, in order to appreciate the functions of its
different parts, Ave must first devote some space to the consid-
eration of the nature and properties of sound.
  If a stone is cast into perfectly calm Avater, a ripple  origin-
ates from the point at which it strikes the fluid, and is  propa-
gated in a series of concentric waves to the edges of the vessel
containing the liquid.
  The waves thus produced on Avater are measured in two
ways:  first, from the crest of one wave to the crest of the next,
the distance being called the  wave length; second, from  the
bottom of the depression to a horizontal line connecting  the
crests: this measurement is called the waA^e height.
  When the waves reach the walls of the vessel containing the
liquid they are not lost, but, being reflected backward, produce
a return system of waves, which, if their crests  correspond to
the crests of the original system, produce a higher wave; but
if the crests of the second system correspond to the depressions
of the first system, they neutralize or interfere Avith each other,
and smooth Avater is the result.
  As, in the  foregoing instance, the vibration caused by  the
impact of the stone on the water is propagated through it in
the form of waves, so the rapid vibrations of a sonorous body
are propagated through the air as waves, which, falling  on  the
ear, produce the impression of sound.  They may be subjected
to measurement just as waves on Avater are measured, and their
length and height accurately determined.  The phenomena of
reflection and interference  of Avater waves are also shown by
Avaves of sound.  If two systems  of  waves of sound are ar-
ranged so that the crests of one correspond to the depressions
of the other, they completely neutralize  each other  if their in-
tensity is equal, silence being produced.       ,
  Though waves of sound are analogous to  water waves, they
are by no means identical; for while the latter pass along  a
single plane, and produce concentric circles  of compression or
elevation, the waATes of sound are propagated along every con-
ceivable plane, passing through the vibrating body as  a  centre,
forming concentric spheres of compression.
  Since waves of sound radiate from a central point of origin,
they gradually diminish in intensity as they occupy a greater
space; but when they fall  on a concave surface, they are re-
  How may waves be measured? What is wave  height? What is  wave length?  Can
waves be reflected ? What is meant by the interference of waves ?  What is sound ?  Can
the waves of sound be measured ? What is the result of the interference of two systems of
sound waves ? What is the difference between waves of sound and waves on water ? 
properties  of sound.                187
fleeted to its central point or focus.   This fact is taken advan-
tage of in the construction of A^arious instruments, such as the
ear trumpet, by Avhich a great number of waves are collected
and conveyed into the ear, and the intensity increased, thereby
enabling  a  person who Avould  otherwise be perfectly deaf to
hear with comparative ease.
  When Avaves of sound fall on dense media they are not lost,
but a portion are reflected, Avhile the remainder are transmit-
ted along the medium.  Air, therefore, is not absolutely neces-
sary to the existence of sound; but, since sounds almost ahvays
come to us  through it, the various phenomena connected with
them are always referred to air as the medium, unless it is oth-
erwise specified.
  The rate  of transmission, or velocity of sound, depends in a
great measure upon the density of the medium through which
it is passing; the other element of velocity is the elasticity of
the medium.  If we notice a bricklayer  working at a suitable
distance, we remark that in cutting a brick the sound seems to
be produced when the trowel is in the air, and not at the mo-
ment of striking the brick: this is  due to the fact that a cer-
tain amount of time is required for the sound to reach the po-
sition in which we  are standing.  Another peculiarity which
we can not  avoid remarking is, that instead of the sound being
single, it is  double.  This is explained by the fact that in pass-
ing to the  observers the  sound has  in part come through the
air, and in part along the wall and earth; in the  latter medium
it moves Avith greater  rapidity than in the former.  The  sound
Avhich was  originally  single has therefore become doubled by
passing through two media with different rates  of velocity.
  The most recent experiments have shown that the velocity
of sound in the air is 1123 feet per second; in water, 4700;
and in  rock from 7000 to 12,000, depending upon  its density,
being the highest in the densest rocks.
  By producing variation in the density  of any given medium,
we can cause the rate of velocity of sound in it to vary.   For
example, atmospheric  air, if subjected to compression, transmits
sounds  with greater velocity, and the intensity is reduced in a
less degree; while if it is submitted to a process of exhaustion,
 What is the effect of concave surfaces on waves of sound?  How does the ear trumpet
act? Is air the only medium in which waves of sound may be conveyed?  What determ-
ines the velocity of the movement of sound ? Give an illustration of the difference of veloc-
ity  of movement of sound in air and a denser medium. What is the velocity of sound in
air—water—rock ?  Does sound move with equal velocity in all rocks ?  What is the effect
of increasing and diminishing the density of air on its power to convey sound ? 
188              INTENSITY, PITCH, QUALITY.
 so as to reduce its density, the conducting power is steadily di-
 minished, until finally it is entirely lost, and we fail to hear a
 bell Avhich is ringing violently in the air-pump jar when the
 density of the air is sufficiently reduced.
   Substances devoid  of elasticity almost  destroy sounds, for
 they neither transmit nor reflect them readily, as any one may
 satisfy  himself by attempting to speak in a room covered with
 tapestry.   While the sides are bare they reflect sounds so that
 the  voice can be heard without any difficulty, but as soon as
 the walls are draped with cloth, the waves, falling on the soft,
 inelastic surface, are destroyed, and it becomes almost  impossi-
 ble  to  hear the  voice in the distant parts of the room, even
 when it is exerted to its utmost power.
   In addition to the properties already mentioned, sound pos-
 sesses three distinct characteristics ;  they  are, 1st.  Intensity or
 loudness; 2d. Pitch or note; and, 3d. Quality.
   The  intensity of a sound is determined by the wave height.
 Tavo sounds may have the same wave length, but that which
 has the greatest wave  height has the greatest intensity.
   The pitch  is regulated by the Avave length, or time of vibra-
 tion. The more rapid the vibrations, the shorter  is the wave
 length,  and the higher the pitch of the note.
   By the quality of a  note we mean to  express the differences
 that exist in a note of any given pitch when it is produced by
 various instruments.   Any one can tell Avhether a given note
 is produced by a piano or a violin;  in both instances the note
 is the same, and yet there is some difference by which we  rec-
 ognize the instrument  which produced it.
  It is  not known on what peculiarity of the sound wave the
 quality of a note depends; but in the ear, both in man and the
 lower animals, there is, as we shall find, a special mechanism
 set aside  for the determination of the quality, as  well as  the
 pitch and intensity of notes.
  In addition to the pitch, intensity, and  quality  of a sound
 the ear also determines its direction.  It is to be remembered
 that the course  of a  sound is  represented by  the radii of a
 sphere,  of which  the point of origin is the  centre;  but it must
 not be  forgotten that sounds  are reflected by  opposing  sur-
 faces, so that when a number of such surfaces are in proper re-
  What other element besides density influences the rate of conduction of sound ?  Give an
 example of the failure of inelastic substances to conduct sound.  What are the three prop-
 erties  of sound ?  How is the intensity of sound regulated ?   How is the pitch of a note
regulated ? What is meant by the quality of a note ?  What is the course of waves of
sound ? 
EXTERNAL, MIDDLE, AND INTERNAL  EAR.
189
lation to each other, the sound can be made to double around
the first surface, and be readily heard behind it.
                    LECTURE XXXIV.
                  ANATOMY  OF  THE EAR.
Divisions  of the Ear.—External Ear described.—Formation of Wax —
  The Tympanic  Cavity and Membrane.— The Bones of the Ear.— The
  Eustachian  Tube.— Openings in the  Walls of the Tympanic Cavity.—
  Muscles  of  the  Tympanic Cavity.— The Parts  of the  Internal Ear.—
  The Vestibule described.— The Membranous Labyrinth.— The Perilymph
  and Endolymph.— Tlie Otoliths.— The Saccule and Utricle.— The Semi-
  circular  Canals.— The Cochlea.— The  Lamina  Spiralis, Modiolus, and
  Spiral Canal.— Tlie Helicotrema.—Distribidion of the Auditory Nerve
  to the Internal Ear.
  The  ear is divided into three parts for convenience of de-
scription.  They are  called the external, middle, and internal
ear.  The external ear consists of the pinna and    Fig. 139.
auditory  canal.   The pinna is composed of carti-
lage, which  is covered by skin, and thrown into
curved  folds, which direct the waves of  sound
into the auditory canal.
  The auditory canal conveys the waves  to the
middle ear;  it is about one inch in length, and is
terminated below by the tympanic membrane, or
drum of the ear.   It is slightly curved, with the
concavity downward, and  is lined
Avith hairs and glands that secrete
an  acrid,  oily material, which pre-
Arents insects entering the organ.
The secretion of these glands, when
dried, forms  the wax found in the
ear.
  Fig. 140,  a a, pinna and audi-
tory canal;  b, middle  ear  or tym-
panic c-vvity; c, hammer  and its
muscles;  d, internal muscle; e, an-
terior muscle ; /, external muscle ;
g, interior half  of membrana tympani;  h, Eustachian tube; i,
internal ear  or labyrinth.
  AVhat are the divisions of the ear?   AVhat parts compose the external ear?  What is the
action of the pinna? What is the length and shape of the auditory canal?  Where does it
terminate ? How is the wax of the ear formed ?
Fig. 140.
External, Middle, and Internal Ear. 
190        THE OSSICLES OF THE TYMPANIC  CAVITY.
   The middle ear or tympanic caA7ity is situated in the petrous
part of the temporal bone; it  is closed exteriorly by the tym-
panic membrane.   It contains three small bones, and commu-
nicates with the back part of the buccal cavity, or pharynx, by
means of the Eustachian tube.  It is very irregular  in its form,
and is filled with air;  in its bony walls there are a  number of
openings, viz., 1st. Meatus externus, or auditory canal, closed by
tympanic membrane; 2d. The opening  of the Eustachian tube ;
3d. The fenestra ovale, and, 4th. The  fenestra  rotunda, both
of which communicate with the internal ear, and are closed by
membranes; 5th. The opening to the mastoid cells, which are
lined by a continuation of the mucous .membrane of the tym-
panic cavity;  6th. The  openings for the muscles and their ten-
dons.
  The small bones contained in the tympanic cavity are  called
the malleus or hammer, the stapes or stirrup, and the incus or
anvil, on account of the resemblance they bear to those imple-
ments.  They are connected together,  forming a chain which
                 extends  across the tympanic cavity  from the
                 membrana tympani to the fenestra ovale, the
                 malleus, a, being attached to  the tympanic
                 membrane, and the stapes, g, to the fenestra
                 ovale.  To the handle of the malleus, near its
                 root, the tensor  tympani, b, the chief muscle
                 of the ear, is  attached; the two laxator tym-
                 pani  muscles, c, d, are also attached to the
                 same bone, while the  stapedius, h, is inserted
into the stapes.   By means of these  muscles  the  membrana
tympani can be relaxed or stretched, and pressure produced on
the contents of the internal ear by the insertion of the stapes
into the membrane of the fenestra ovale.
  The mucous membrane of the tympanic cavity ih very thin
and highly  vascular; it is continuous with the  mucous  mem-
brane of the pharynx by  the Eustachian tube, and covers the
ossicles, tendons, and muscles contained in the cavity.
  The internal ear is called the labyrinth  on account  of the ir-
regularity of the parts  composing it.   It consists of the vesti-
bule (a, b, t, Fig. 142), semicircular canals (o, g, c, Fig. 142), and
  Where is the middle ear ? What name is given to it ? How does the tympanic cavitv
communicate with the pharynx?  What openings are found in the walls of  the tympanic
cavity ?  What are the names of the bones of the tympanic cavity ? To what membrane is
the malleus attached?  To what membrane is the stapes attached? What muscles are
found in the tympanic cavity ? To what part of the malleus is the tensor tympani attached ?
What is the action of these muscles ?  Describe the tympanic mucous membrane. What
name is given to the internal ear ? Name the parts composing the labyrinth.
 
THE VESTIBULE AND  SEMICIRCULAR  CANALS.      191
Fig. 142.
Fig. 143.
Labyrinth magnified two Diameters.
Exterior of the three Semicircular Canals and
             the Cochlea.
Membranous Labyrinth of the Canal.
cochlea  (??, d, e, Fig. 142), which are
hollowed out  in the petrous  part of
the  temporal bone,  and  communicate
externally with the  middle  ear,  and
internally with the  meatus  internus,
through  Avhich  the  auditory  nerve
passes.
  The vestibule is ovoid  in figure, and
the centre of communication of the other divisions of the inter-
nal ear; it is lined interiorly by a membrane that contains a
fluid called the perilymph.  In this fluid a sac-like body, called
the membranous labyrinth, is placed, which is not attached to
the bony walls of the cavities, but is separated from them by
the perilymph.
  The  membranous  labyrinth contains  the  terminal filaments
of the  auditory nerve, and is filled  with fluid.   The portion
that occupies the vestibule is divided by a central constriction,
and caused to assume a dumb-bell shape.  To one of the divi-
sions the name of the saccule is given;  the  other is called  the
utricle;  from it tube-like  processes are given off, which occupy
the cavity of the semicircular  canals o,p,q.  The saccule and
utricle each contain an otolith, or minute stone-like body.
  The semicircular canals are  three in number.   They  are so
arranged as to occupy three planes at right  angles to each oth-
er, represented by the faces of a cube.  They are lined by a
membrane which contains the perilymph, and in this liquid the
tube-like portions of the membranous labyrinth are suspended
by the  vessels which pass to them to convey the required  nu-
trition.   The fluid contained in the  membranous labyrinth is
almost identical in composition Avith  the perilymph;  it is call-
ed the endolymph.
  Describe the vestibule.  AVhat is the perilymph ? Describe the membranous labyrinth.
What names are given to the divisions of the vestibular portion of the membranous laby-
rinth ? What are the otoliths, and where are they found ?  Is the membranous labyrinth at-
tached to the walls of the cavities in which it is placed? Describe the semicircular canals.
What is the endolymph ? 
192          THE  COCHLEA AND LAMINA SPIRALIS.
Fig. 145.
  The cochlea resembles in its shape a common snail-shell.  It
is composed  of a central conical  axis, called the  modiolus,
around Avhich a conical tube, called the spiral canal, is wound
                             for two and a half turns.   In the
                             spiral canal there is a thin sep-
                             tum, called  the  lamina spiralis,
                             Avhich is  composed of bone, mus-
                             cle, and tendon, and extends near-
                             ly the whole length of the canal,
                             dividing  it  into two tubes, the
                             scala  vestibuli, which  communi-
                             cates with the vestibule, and the
                             scala tympani.  At  the apex  of
                             the spiral canal the scalae commu-
                             nicate with  each other by  an
                             opening called the helicotrema.
                                The fibro - serous  membrane
                             AAmich lines the cochlea is contin-
                             uous with that of the vestibules
and semicircular canals;  it  secretes the  perilymph, which is
found in all parts of the internal ear.
  The portion of the auditory nerve  which is distributed to
the cochlea passes up the modiolus, and the filaments cross the
                             Fig. 146.
Section of Cochlea.
                      Distribution of Cochlear Nerve.

lamina spiralis, which is about one tenth of an inch wide at its
base, and terminates almost in a point at the helicotrema.  The
filaments of the nerve are consequently shorter and shorter to-

  What is the shape of the cochlea ?  What is the name of the central axis of the cochlea?
What is the spiral canal ?  What is the lamina spiralis, and of what is it composed ?  What
are the two  scalae, and what names are given to them ? What is the helicotrema?  What
is the nature of the membrane that secretes the perilymph ?  How is the auditory nerve dis-
tributed to the cochlea ?  Are the filaments of the nerve all of the same length ? 
FUNCTION OF THE PINNA.
193
ward the apex of the cochlea, and may be regarded as resem-
bling the strings of a harp or piano.
  The internal, middle, and a part of the canal of the external
ear are contained in the petrous portion of the temporal bone,
which, in the articulated skull, lies at its base, so that they are
perfectly protected.  The dense, compact structure of this bone
is very favorable to the conveyance  of sounds, and they are
retained until they have been analyzed by the mechanism of
the ear, when they are destroyed in the ear by a special appa-
ratus.
  The  auditory nerve gains access to the internal ear by an
opening near the apex, of the petrous bone, called the meatus
auditorius internus, in contradistinction to the opening at its
base by Avhich the waves of sound are admitted.
  LECTURE XXXV.

HEARING AND VOICE.
The Elements of Sound dealt with by the Ear.—Function of the' Pinna
  and Auditory Canal.—Function of the Membrana Tympani.—Func-
  tions of the Ossicles.— Of the Eustachian Tube.—Function of the Vesti-
  bule.— Of the Semicircular Canals.— Of the Cochlea.—The Destruction
  of Sounds in the External Ear.—Development of the Ear.—The Ear in
  the Lower Animals. — Voice  exists in Air-breathing Animals. — The
  Larynx described. — Vocal Cords.— Character of Song.— Of Whispers.
  — Of Voice or Speech.

  The ear deals Avith four elements of sound, viz., Direction, In-
tensity, Pitch, and Quality.   The first is found by determining
the relative intensity of the  impressions produced on both ears,
the advantage of a  duplication of the  organs being that  Ave
may be advised of the existence of sounds on all sides, and  ap-
preciate their true  nature without being obliged to turn the
head.
  The  waves of sound which  fall on  the pinna  are by  its
curved surfaces directed into the auditory canal; the object of
the pinna, therefore, is to increase the  number  of Avaves  of
sound Avhich  enter the canal by  acting as a reflector.
  At the bottom of the auditory canal sound waves come in
contact with the drum or tympanic membrane, the tension of
  In what bone are the internal and middle ear placed ?  How does the auditory nerve
reach the internal ear ?  With what elements of sound does the ear deal ?  How is the di-
rection of a sound determined ?  AVhat advantage is gained by the possession of two ears ?
What is the function of the pinna ?
                             N 
194        FUNCTION OF THE MEMBRANA TYMPANI.
which can be varied by the action of the small muscles insert-
ed into the bones of the tympanic cavity.
  If the tension  on  the membrana tympani  is increased by
compressing the air in the tympanic cavity through the Eusta-
chian tube, sounds become dull and obscured.   When the op-
erations of the muscles attached to the membrane are interfered
Avith, sounds often become almost unendurable from their in-
tensity.   It is therefore supposed that it is the function of the
tympanic membrane, or rather of the tensor tympani muscle, to
measure the intensity of the sound conveyed to the interior of
the organ by determining  the force required to produce  the
right amount of tension in the tympanic  membrane.  At  the
same time, the volume of sound allowed to enter the ear is also
regulated.
  It was formerly supposed that the object of the chain of
bones was to convey the sounds with greater perfection to  the
internal ear; but the jointed nature of the apparatus entirely
precludes this idea, for such a structure is highly  injurious to
the conduction of sound.  The true function of the bones is to
vary the tension of the membrana tympani by applying  in an
advantageous manner the force produced in the  contractions
of the tensor tympani and laxator muscles.
  The precision and small amount  of contraction  of the mus-
cles of the ear in their action on the drum is rivaled by  those
of the larynx, the muscles of the vocal cords being able to pro-
duce a variation  of one semitone by a contraction of y To Troth
of an inch.                                              .
  The object of the Eustachian tube is to giA^e perfectly free
communication with the external air, an  equality of pressure
on  both  sides of  the membrana tympani seeming to be  essen-
tial to its proper action.   Whenever the Eustachian tube is
closed from any cause, as in sore throat, by the accumulation
of mucus in the inflammations of the mucous membrane of the
pharynx, the sounds  become muffled and indistinct, and regain
their clearness when the tube is again  freed from all obstruc-
tions.
   From the above facts, we conclude that it is the function of
the membrana tympani to determine  the intensity  or  wave
height of sounds.
   There still remain two elements of sound to be ascertained
  AVhat is the effect of increasing the pressure on the tympanic membrane ?  What is the
function of the membrana tympani ? What is the function of the chain of bones in the tvm-
panic cavity ? What is the function of the Eustachian tube ?  What is the effect of tempo-
rary closure of the Eustachian tube ? 
           DETERMINATION OF PITCH AND QUALITY.        195

by the internal ear, ATiz., Pitch and Quality.  It is to be recol-
lected that  the vestibule  is the entrance to the cochlea  and
semicircular canals, but it probably has no special function be-
yond the conveyance of the sound to those organs, the presence
of the otoliths in the sacculus and utricle being accounted for
by supposing that they are rudimentary relics, like the mam-
mae in males.
  The function of the cochlea is to determine the pitch of the
sound, as Ave shall endeavor to show by the consideration of its
construction.
  It is a well-known fact in acoustics, that if in the Adcinity of
any stringed instrument, as a piano, a note is sounded on some
other instrument, the corresponding string in the piano will be
thrown into vibration, and produce the same note.   On the
lamina spiralis of the cochlea the auditory nerve is distributed,
so that the filaments are of different lengths, like the strings of
a piano.  WheneArer there is similarity of structure, Ave may
argue similarity of action.   It is therefore probable, that as the
proper string of the piano vibrates in unison Avith the note pro-
duced in its vicinity, so the proper fibrilla on the lamina spi-
ralis is affected by the note falling upon it, and the impression
is conveyed to the brain.
  When a note has produced its proper effect in the cochlea it
becomes necessary that it should be destroyed, or the ear would
be filled with the dying echoes of notes that are passing away.
The final destruction of the note is accomplished by taking ad-
vantage of the principle of interference.  It has been stated, in
describing the cochlea, that the lamina spiralis divided the spi-
ral canal, so that two tubes, the scala vestibuli and scala tym-
pani, were formed, which are of unequal lengths, and communi-
cate above through the helicotrema.  In order to reach the fil-
aments of the auditory nerve, the waves of sound must pass up
the two scalae, and finally meet at the helicotrema  in such a
manner that the crest of one  system of waves corresponds to
the depression of the other, and they  mutually destroy  each
other after they have produced their proper impression.
  In  addition  to its formation, there are facts in the compara-
tive, history of the organ of hearing in the lower animals which
confirm the opinion that the function of the cochlea is to de-
termine the pitch or wave length of sound.
  What is the function of the vestibule? How is the presence of the otoliths accounted
for? AVhat is the function of the cochlea? Upon what principle does the action of the
cochlea depend ?  How is the formation of echoes in the cochlea avoided ? Are the two
scalae of equal lengths ? 
196          THE EAR IN THE LOWER ANIMALS.
  The semicircular canals were formerly supposed to determ-
ine the direction in which a  sound came to the ear, because
they were placed in three different planes at right angles, but
it is now thought that they detect the quality.   This conclu-
sion is drawn from facts in comparative anatomy, which show
that the canals often exist in creatures which can determine the
quality of a sound, but do not possess a cochlea.
  The simplest form of ear merely appreciates the existence of
sound; it consists of a small  sac, containing fluid, and an oto-
lith.  When the waves of sound fall on the apparatus, the oto-
lith is caused to vibrate, and, striking the walls of the sac, irri-
tates the nerve fibres distributed to them, and produces the
impression of sound.  By means of two  such organs its direc-
tion is determined.  The next step in advance  is the addition
of a tympanum, for measuring the intensity; the semicircular
canals,to detect the quality;  and,finally,the cochlea,to ascer-
tain the pitch.
   In its various stages of development, the ear  of  the foetus
shows  a gradual  advancement toward perfection, similar  to
that we have detailed above, being at  first like that of a fish,
consisting of a sac and otolith, but finally reaching its  perfect
state.
   There are some singular and interesting evidences among the
lower animals  of adaptation of means to an end in the auditory
apparatus.   In the predaceous  creature, the pinna and meatus,
or auditory canal, are directed forward, so as to  enable it to fol-
low its prey, while in timid animals they are directed back-
ward, so as to favor escape during pursuit.  BurroAving quad-
rupeds are  provided with membranous valves, to prevent dirt
entering the canal during their subterranean operations.   Many
other interesting  instances might be detailed, but we must re-
fer the reader to the works on Natural History, and pass to the
consideration of

                         THE VOICE.
   Language is the direct means of communication with our fel-
loAv-men.  By it  we make known to each other  our pleasures
and sufferings, and express the thoughts, ideas, and  commands
which control the destinies of men  and nations; yet without

  What was formerly supposed to be the function of the semicircular canals ? What is the
 present theory regarding the function of the semicircular canals?  What is the  simplest
 form of ear ? Through what stages does the human ear pass in its development ?  Describe
 some of the peculiarities of the auditory apparatus in the lower animals. 
PRODUCTION OF SOUNDS.                197
Fiff. 147.
 the sense of hearing it is useless; Ave may therefore regard it
 as being auxiliary to that sense.
   The poAver of producing a noise appertains to air-breathing
 animals, creatures Avhich are aquatic not being able to produce
 sounds  by which they may hold communication with other
 members of their own species.   The voiceless state  of aquatic
 creatures is  due to the fact that, since they do not possess
 lungs, there is no expired air to employ for the purpose of pro-
 ducing sounds.
  ^ In insects sounds  are sometimes formed by the rapid rub-
 bing of  horny surfaces  against
 each other; sometimes by the vi-
 bration  of the wings, as in mus-
 quitoes;  in others by forcing the
 air from the trachea or air-tubes
 through the A7alves of the spira
 cles which  close the  orifices of
 those organs: a rapid vibration
 of the valves is the consequence,
 and sounds are produced in  the
 same manner as in  the  accor-
 deon.
   In birds there is a double  lar-
 ynx, one being placed  at  the
 back part of the mouth, and  the
 other at the bifurcation of the trachea.  The first is  employed
 in the ordinary act of respiration, and the second in the pro-
 duction of song.
   In man there is but one  larynx, commonly known as the
 Adam's apple.  The vocal cords, r, s, are extend-
 ed across its opening, o, which is protected above
 by the epiglottis, i.
   To the cords muscles  are  attached, by which
 they may be subjected to various degrees of ten-
 sion, and the nature of the opening altered.  By
 varying  the  tension of the cords, and the force
 Avith Avhich the air is driven  through the chink-
 like opening they inclose, various notes are pro-
 duced.
   Song is the result of the Aubration of the column of air  in
  What class of animals possess the power of uttering sounds ?  What are the methods re-
sorted to for the production of sounds ?  AVhat is the peculiarity in the larynx of birds ?
 Describe the larynx in man.  What are the vocal cords?  How are the notes produced in
singing ?
Spiracle of Insect.
Fig. 143.
The Vocal Cords. 
198
NATURE OF  ARTICULATE SPEECH.
the larynx and trachea, but  speech is caused by the action of
the tongue, lips, and muscles of the mouth.   The simplest form
of speech is the whisper;  it is produced by forcing a current
of air through the buccal cavity, while its parts are thrown
into the  proper  position  for  producing different words.  In
speaking the same movements are employed, but, in addition, a
note is at the same  time formed in the larynx, which  is modi-
fied as it passes through the mouth, and speech is  the result.
  An ingenious  experiment, first advanced by M. Deleau, has
demonstrated the above explanation of the nature of speech in
the most satisfactory manner.  It consists in passing an elastic
tube through  the  nostrils to the  back part  of  the  mouth;
through this another  person blows gently, while the  experi-
menter throws the parts of the buccal cavity into the positions
for producing any given word.  The result is  a whisper.  If,
at the  same time, the experimenter causes a sound to be pro-
duced in his own larynx, there is a double articulation, one as
a whisper, the  other as audible speech, demonstrating that ar-
ticulate speech is produced by the mouth.
  Speech and language are  of great interest to the historian,
for by tracing  the roots of Avords of different tongues he can
often discoA^er  the influence of a conquering on a conquered
race, and determine the  track through which a  nation has
passed in its career of conquest or of flight.
                    LECTURE XXXVI.

             NATURE AND PROPERTIES OF LIGHT.

Theories regarding Light.—Existence, Nature, and Properties of the Ether.
  —Effect of Temperature on the Intensity of Light.— Compound Nature
  of Light.—Action of Prisms.—Action of Surf aces and Media on Light.
  —Reflection, and the Law which Governs it. — Causes influencing the
  Intensity of the reflected Ray.— Transmission.—Absorption.—Interfer-
  ence.—Interference and Prismatic Spectra compared.—Refraction de-
  scribed.— Order of Refrangibility of Colors.— Theory of Coloration of
  Surfaces.

  Until quite recent times, the doctrine of Newton regarding
light was almost universally adopted.  He taught  that  it was
produced by the emission of exceedingly minute particles from

  What is the difference between song and speech ?  AAThat is the difference between whis-
pering and speech? Describe the experiment of Deleau.  What was Newton's theory of
light? 
THE  WAVE THEORY,
199
the luminous body, which, falling  on the retina, or sensitive
nervous coat of the eye, produced the sensation of light.
  The emission theory of Newton has been finally set aside by
the wave theory,  which was perfected by the researches of
Young and Fresnel.  It supposes that the particles of the lu-
minous body are in a state of rapid vibration, and produce in
the ether waves, which, falling on  the retina, give rise to the
sensation of light.
  The ether, the  existence of Avhich is necessary to the waAre
theory, is supposed to be  an exceedingly attenuated medium
Avhich pervades all space,  exists  in the interior of transparent
substances,  extends among the planets, and fills the interstel-
lar spaces.   The presence of such a  medium is demonstrated by
the fact that comets and like cosmical bodies are subject to va-
riations and retardations in their times of passage through their
orbits, which can only be explained by the resistance afforded
by some ethereal medium.
  The marvelous rapidity (195,000 miles in a second) with
Avhich light traverses space, as well as the manner of the move-
ment, is admirably illustrated in the following quotation: " Mo-
tion may be  propagated  and matter affected to a great dis-
tance  without the transmission  of matter itself.  Imagine a
straight  tube filled with peas reaching from London to York
in a horizontal position.   If I force an additional pea in at one
end of the  tube, a pea will drop  out of the tube almost simul-
taneously.   Noav if the means by which this was effected Avere
as imperceptible as the propagation of light, or of electricity
transmitted through good  conductors, Ave should be astonished
at the rapidity of the transit, and imagine that the identical
pea put into the tube in London had arrived at York in an in-
credibly short space of time; but, knowing the condition of
the proposition, we perceive that motion may  be propagated
throughout a very long line  almost instantaneously, without
moving each particle of matter far from its original position, or
communicating to those particles much momentum."
  In 1846, Professor J. W. Draper  demonstrated that all solid
bodies become luminous at the  same temperature..  The point
at which such substances  first become visibly red-hot  is 977°
Fahrenheit, and their brilliancy steadily increases Avith  the ele-
vation of temperature, so that at  2600° the light emitted is for-

  What is the wave theory? What is the ether?  Why is such a medium supposed to ex-
ist?  At what temperature do solids become luminous? How does increase of temperature
affect the intensity of the light emitted  ? 
200
COMPOUND NATURE  OF LIGHT.
ty times as intense as at 1900°.  Gases, on the  contrary, re-
quire a far higher temperature than solids to render them vis-
ibly red-hot, as any one may satisfy himself by holding a coil
of platinum wire over the flame of a spirit lamp.  The ascend-
ing gas from the flame is not luminous, but the  moment the
wire is placed in it the temperature is so high  as  to cause the
platinum to  emit light, thereby  demonstrating that solids re-
quire a far lower temperature than gases  to cause them to be-
come luminous.
   Contrary to what we should naturally expect, white or col-
orless light is not simple, but compound, consisting of no less
than  seA^en different varieties of colored  lights.   There are a
number of experiments which show this fact, for which we are
indebted to Newton, who found that  if a ray of colorless sun-
light is caused to fall on a prism  (or column of glass whose sec-
tion is triangular), it is immediately decomposed into seven col-
ors, viz., red, orange, yellow, green, blue, indigo,  violet.
  Not only may white light be  demonstrated by analysis to
consist of seven colors, but we can by synthesis show the same
fact; for if the beam of light, as it leaves the first prism, is caught
on a second prism, equal to the first in all respects, and placed
with its base parallel to the edge of the first prism, so  that it
may act in the opposite manner, it will recombine the colored
rays, and produce Avhite light.
  The compound nature of white light  may  be  shown in a
less perfect manner by mixing together  in  proper proportion
poAvders of the colors of the  spectrum, when a white powder,
of a slight grayish tint, is obtained.   Another method of illus-
trating the same fact is to paint the spectrum on a circular disc
of pasteboard to which a rapid movement of  rotation  can be
imparted;  when the motion  reaches  a certain rate the  colors
become blended, and a light grayish tint is produced.
  The action of surfaces  and media on light is to cause it to
undergo reflection, transmission, absorption, interference, or re-
fraction.
  1st. Reflection.—When a ray of light falls on a polished
surface, it is. reflected or thrown back  on the opposite side of a
perpendicular drawn to the  surface at the point of impact of

 Do gases become luminous at the same temperature  as solids ? Is light simple or com-
pound ?  How many colors are found in white light ?  What is a prism ?  Name the colors
produced by the action of a prism on white light.  How may the compound nature of light
be shown by synthesis? How may the compound nature of light be illustrated by powders?
How may the composition of light be shown by the revolving card ?  AA7hat is the action of
surfaces and media on light? What is reflection? 
DISPOSAL OF  RAYS BY SURFACES.
201
the ray.   The first is called the incident, and the second the re-
flected ray.  The angle between the incident ray and the per-
pendicular is  called the angle of incidence, while that betAveen
the perpendicular and the reflected ray is called the angle of re-
flection.   The laAv of reflection may be briefly stated as follows:
  When a ray falls on any polished swface it is reflected, and
the angle of reflection is equal to the angle of incidence.
  The amount  of light reflected depends on the intensity of
the incident ray, the angle of incidence, and the nature of the
surface, a polished surface of pure silver possessing far greater
reflecting power than a similar surface  of iron or other metals.
  Transmission.—If a ray falls on a transparent medium, such
as glass, a small proportion  is reflected by the  surface, Avhile
the remaining part  is transmitted, or allowed to pass through
the medium.
  Absorption.—When light falls on rough, dark surfaces, it is
absorbed, but not destroyed, for the surface converts  it into
some other force, as, for example, heat.  During the transmis-
sion of a ray through  a transparent medium a portion of the
light is absorbed, so that, in  addition to the loss by reflection
from the surface, there  is also loss by absorption.
  Interference.—A ray of light may be  reflected in  such a
manner that the waves composing it interfere with each other,
the crests of one system corresponding to the depressions of an-
other, and producing darkness.   The phenomenon of interfer-
ence may be illustrated by causing a beam  of light to fall on a
very narroAV slit, and then receiving the rays that pass through
the slit on a screen  in a dark room.   The image formed is not
a uniform spot of light, but consists of alternate light and dark
lines; the first being produced by the coincidence of crests of
waves, the second by the coincidence of crests and depressions.
  If a ray is allowed to fall on a ruled  surface of steel, glass, or
any other suitable substance, the reflected light is decomposed
by interference, and a number of spectra produced.   The spec-
trum of interference contains the  same colors as the prismatic
spectrum, but there is a slight difference in their position; the
order of the colors is the same in both, but in the interference
spectrum the yellow is in the middle, while in the prismatic

  What are the incident and reflected rays ? What are the angles of incidence and reflec-
tion ? What is, the law of reflection ?  AVhat conditions influence the quantity and intensity
of the reflected ray?  AAliat is transmission?  What is absorption?  Is the absorbed ray
destroyed?  AVhat  is interference? How may interference be illustrated? What change
is produced in light reflected by ruled surfaces ?   How does the interference differ from the
prismatic spectrum ? 
202
THEORY OF  COLORATION.
spectrum it is in the lower part, the orange and red being com-
pressed, and the violet and blue dilated.
  The colors  shown by thin transparent substances, as soap-
bubbles, and the beautiful tints of certain shells, and such fine-
ly-ruled surfaces, are all phenomena of interference.
  Refraction.—If a ray falls perpendicularly on a transparent
medium  with parallel  surfaces, it passes directly through it,
and continues its course in a straight line; but if it falls on the
first surface at any other angle  than a right angle, it is bent or
refracted from its original track during its passage through the
medium, and on emerging from it into the air is  again bent, so
that the course of the emergent ray is parallel to the  track of
the incident ray.
  If the surfaces of the medium are not parallel  to each other,
the emergent  ray will not be parallel to the incident ray, even
though it is perpendicular to the first surface.  Advantage is
taken of this fact in the construction of prisms, the surfaces of
which are arranged at an angle to each other,  so as to produce
the greatest amount of refraction in a ray.
  When a beam of light falls on the first surface of a prism at
the proper angle, it is decomposed during its  passage  through
the instrument; and if the emergent beam is caused to fall on
a screen placed in the proper position, a spectrum is produced.
If Ave examine the colors in the prismatic spectrum as regards
the amount of refraction, we find that the red has been bent
from its original course less than the others; it is  therefore
called the least refrangible ray.  The next in order of refrangi-
bility is the orange; then the yelloAv, green, blue, indigo, violet.
   Coloration.—Reflection and transmission may both produce
colors by the decomposition of white  light;  absorption, also,
may decompose light.   When the absorption is perfect the sur-
face seems to be black; but when certain colors only are  ab-
sorbed, and the remainder reflected, the surface has the color of
the reflected fays.   A red surface, therefore, owes its tint to the
fact that it has absorbed all the  other colors of which light is
composed, except the red, which is reflected; the same is the
case with the yelloAv, violet, and other colors.  When tAvo or
more colors are reflected, the  surface possesses  the compound
tint formed by their union.
  What is refraction, and how is it produced?  What condition is necessary in order that
the emergent ray should be parallel to the incident ray ?  What is the order of refraction of
the  different colors of the spectrum, commencing with the least refrangible ?  Does absorp-
tion produce decomposition of light?  What is the color of a surface that absorbs light com-
pletely ? What is the theory of coloration of surfaces ? 
COMPOUND  CHARACTER  OF THE  SPECTRUM.       203
                    LECTURE XXXVII.
                   THE PROPERTIES .OF LIGHT.
 The three Forces in the Spectrum.—Presence of Heat and its Point  of
   Maximum Intensity demonstrated.—Region of Maximmh Intensity  of
   Light.—Action of Yellow Ray on Compounds of Carbon.—Presence
   of Chemical Rays demonstrated.—Positive and negative Chemical Rays,
   their Points of Maximum Intensity.—Lenses classified.—Action of con-
   vex Lenses.— Of concave Lenses.— Causes of Variation in focal Distance
   of convex Lenses.—Spherical Aberration described.— Correction of Spher-
   ical Aberration.— Chromatic Aberration  described, and the Methods  of
   Correction.—Achromatic Lenses.—Penetrating Power of a Lens.—Rela-
   tion of penetrating Power to the Diameter of a Lens.
   We  have demonstrated that white light is composed of sev-
 en distinct colors;  we are now to find that it also contains heat,
 and chemical or electrical rays, in addition to the illuminating
 or light rays.
   If the  spectrum is  caused to fall on a blackened surface
 which has been moistened with alcohol, or some other vaporiz-
 able fluid, it is found that the fluid evaporates  Avith the great-
 est rapidity in the red ray, less in the orange, and least in the
 violet; we therefore  conclude that in the spectrum  there are
 rays of heat as well as of light, and the point of maximum in-
 tensity of the heat rays is in the red.
   If the spectrum is caused to fall on paper covered with very
 fine print, Ave find that  the finest print  can be  read with the
 greatest facility and at the greatest distance in  the yelloAv ray.
 The point of maximum  intensity of light, therefore, does not
 correspond to that of heat, but is found in the yelloAv ray, from
 Avhich it steadily diminishes to the  upper ancTloAver part  of
 the spectrum.
   When a spectrum is caused to fall  on  a toav  of tubes Avhich
 haATe been filled  Avith Avater, and  a  portion of grass  or some
 other vegetable  substance placed in  each of them, it is found
 that oxygen is evolved Avith the greatest rapidity in the  tube
 in the yelloAv ray.  The  oxygen, under these circumstances,  is
produced  by the  decomposition of the carbonic  acid dissolved
  AVhat are the three forces found in the spectrum?  How may the presence of heat be
>hown ?  In what part of the spectrum do we find the maximum intensity of heat ?  How
may the maximum intensity of light be shown ?  AVhere is it found? 
204
THE  CHEMICAL  RAYS.
in the water, the vegetable material appropriating the carbon,
and setting the oxygen free.   Since the action goes on Avith
the greatest rapidity in the yellow ray, it follows that, since the
yellow is the region of maximum intensity of light, it is the
light, and not the other constituents of the sunbeam, that is en-
gaged in the decomposition of the compounds of carbon; and
since that element is the chief constituent of the sensitive coat
of the eye, the yellow ray  is the most unendurable, and affects
that organ Avith the greatest power.
  The presence of chemical rays in the sunbeam may be illus-
trated by causing the spectrum to fall on a sensitive surface of
iodide or bromide of silver, such as is employed in making pho-
tographic pictures.  When the image is developed in the prop-
er manner, it is found that the deepest stain is produced in the
portion which corresponds to the violet ray.  The region  of
maximum intensity  of the chemical rays, therefore, differs from
those of heat and light, being  in the violet.
  Not only are chemical rays contained in the spectrum, but,
as Professor Draper has shown, there are two classes  of chemi-
cal rays, the positive and the negative.  This fact may be illus-
trated by  causing the spectrum to fall on a  sensitive plate
which has been previously exposed to a light of moderate in-
tensity.  On  developing the image, we  find that  it is longer
than when the plate has been  carefully protected from  the
light.  The portion of the stain that corresponds to the colors
from the yellow to  the violet of the spectrum, and beyond, is
deeply stained, while that  which corresponds to the yellow, or-
ange, red, and the region  beyond, is stained to  a less degree
than the remainder  of the plate.
  The foregoing experiment demonstrates that  in the region
of the orange and yellow  the  action has been  the opposite of
that in the violet and blue, the first undoing the work of the
feeble light to which the sensitive plate Avas exposed, Avhile the
second increases it.   In the first the action is  negative, in the
second it is positive.
  Since there are two classes of chemical rays in the spectrum
there are also two  points of maximum intensity:  that of the
positive  rays is in the violet,  that of the negative rays in the
  In which color of the spectrum is carbonic acid decomposed by vegetables with the great-
est rapidity ?  Which force is engaged in the decomposition of carbon compounds ? AA'hich
ray has the greatest intensity of action on the sensitive coat of the eye ?  How may the pres-
ence of chemical rays in the spectrum be demonstrated?  In which color of the spectrum i6
the chemical force most intense ?  How may the existence of positive and negative chemical
rays in the spectrum be demonstrated ?  Where are the regions of positive and negative
maximum intensity ? 
           CHARACTERS AND PROPERTIES  OF LENSES.       205

red, Avhile in the yellow  they both  gradually meet, and, de-
stroying each other, produce a region  void of action.

                           LENSES.
  There is a great variety in  the  forms  of lenses, but Ave  may
reduce them to tAvo classes:  1st. Those which are thickest at
the centre; 2d. Those which are thickest at the circumference.
The first Ave shall speak of as  convex  lenses, the second as con-
cave.
  When parallel rays of light fall on a convex  lens, they are
converged, and, passing from  the  opposite surface, meet  and
cross each other at a certain distance from it, forming the focus,
from which point they pass on, unless they are intercepted, and
become divergent.   When parallel rays  fall on a concave  lens,
they diverge on leaving the opposite surface;  they never meet,
and consequently the  lens has no true focus.
  The action of a  lens may be readily understood by examin-
ing the action  of prisms on parallel rays.  When the ray  falls
on  the first surface at a suitable  angle, it is  refracted toward
the base of the prism  without being decomposed;  but the an-
gle Avhich the ray forms Avith the first surface may be so regu-
lated that the ray is  both refracted  and decomposed, and a
spectrum formed.
  The first condition is that Avhich exists in a lens, for we  may
regard a convex lens as being composed  of a great numbei* of
sections of prisms, so arranged that their bases all meet at the
centre of the lens.   The action of a prism is to refract the  rays
toward its base; all the prisms of which the lens is composed
therefore refract the rays toward the line passing through the
centre of the lens, and, causing them to cross each other  at a
short distance from it, produce the focus. t
  In the concave lens, on  the contrary, the sections of prisms
are arranged so that the bases are at the circumference of the
lens;  consequently the rays are refracted, so  that they recede
from its axis and become divergent.
  The focus, or point of crossing of the refracted rays that have
passed through a convex  lens, A'aries in its distance from the
surface.   The conditions which govern the distance of the focus
  What is the condition of the chemical rays in the yellow? To what two classes may
lenses be reduced?  AVhat change does a convex lens impress on rays of light?  What is
the focus of a lens ? AArhat is the action of a concave lens on parallel rays ?  How may the
action of concave and convex lenses be explained ?  AVhat are the conditions which cause
the distance of the focus from the lens to vary ? 
206        SPHERICAL AND CHROMATIC ABERRATION.

are, first, the curvature of its surface, and, second, the distance
of the object.
   In  lenses of the same diameter, that which has its surfaces
described by the shortest radius, or, in other words, that which
is  thickest in  the centre (providing  the circumference in all is
equal in thickness), will have the shortest focus;  and the less
the convexity, the greater is the focal distance of the lens.
   The variation of focal  distance, caused by variation  in the
distance of the object, is due to the fact that Avhen the object is
close  to the lens, the rays emitted from its surface are diverg-
ent, while as it recedes from the lens the divergence is less, un-
til finally, at  great distances, they  virtually become  parallel.
When the sun's rays are  employed  to determine the focal dis-
tance of a lens, we are dealing with parallel rays; but when an
artificial light is used, unless the distance is very great, we em-
ploy  divergent rays, and the lens has increased work to accom-
plish in order to bring the rays to a focus;  it consequently re-
quires increased focal distance.
   In  lenses of the same focal distance, those with the greatest
diameter give an  image  which is very indistinct when com-
pared with those of small diameter.  This is due to the fact
that  the different parts of the lens  do not bring the rays fall-
ing on them to the same focus.   It is called spherical aberra-
tion,  and may be relieved by reducing the diameter of the lens
by the use of a diaphragm.   But it can be corrected by a sys-
tem of local correction, in which zone after zone of the lens is
polished down  until all parts haA^e  the same focal distance  as
the central region.
   The image produced by an ordinary lens is  not  only indis-
tinct, but also colored on its edges.  This is called chromatic
aberration;  it  is  corrected by the use of compound lenses,
formed of crown and flint glass, ground to fit each other accu-
rately.   Though each of these glasses give a chromatic image
Avhen used alone, that formed by the compound arrangement is
entirely free from color, the  error of one lens completely neu-
tralizing that of the other.  It is called an achromatic lens.
   In lenses of the same focal length, that  of the greatest diam-
eter has the greatest penetrating power, by Avhich is meant the
  Does the lens of the least or the greatest curvature have the shortest focus' ?  How does
variation in the distance of the object cause variation in the focal distance of the lens ?  In
lenses  of the same focal distance, which will give the sharpest image ?  What is spherical
aberration?  How is it produced?  How may spherical aberration be relieved ?  How may
it be corrected ? What is chromatic aberration, and how is it produced ?  How is spherical
aberration corrected?  AVhat is an achromatic lens? What is meant by the penetrating
power of a lens ?  What determines the penetrating power of a lens ? 
THE STRUCTURE OF  THE  EYE.
207
power  to  define  fine  lines  and  discover  minute  markings.
Whenever, therefore, Ave  attempt  to  correct spherical or chro-
matic  aberration by reducing the diameter of the lens, Ave re-
duce its penetrating power.  In the correction of chromatic ab-
erration, the  same  system of polishing concentric zones is fol-
loAved as was described when treating of spherical aberration,
but the difficulties  are greater, since there are four surfaces to
operate on instead  of tAvo.
                   LECTURE XXXVIII.
                  ANATOMY OF THE  EYE.
The Orbits.—Shape and Diameter of the Eyeball.—Its Tunics or Coats.
  — The Sclerotic.— The Choroid.— The Black Pigment and the Retina
  described.— The Cornea and the three Humors.—Their relative Density.
  — The Lens described.— The Hyaloid Membrane and its Function.—The
  Iris, its Composition and Function.— The Retina and Optic Chiasm.—
  The Appendages. — Position of the Muscles.—Tlie Conjunctiva.— The
  Lachrymal Gland and Nasal Duct.— The Eyelids, Glands, and Lashes.
  The eyeball is placed in the  orbital cavity, so that it is pro-
tected from violence and injury on all
sides  except anteriorly, and  even there    /•**>
is shielded as much as possible by the
overhanging brow and hard ring of
bone  Avhich surrounds  the  bases of
these cavities.   The axes of the orbits
are in the  lower animals very  diverg-
ent, so as to give them poAver of seeing
laterally to a considerable extent; but   Position of Eyeball ta 0rbital Cavity.
in man they are  nearly parallel, and di-
rected forward, lateral vision being obtained by the movement
of the head on the vertebral column.
  The globe of the ball  is over one inch in diameter, and near-
ly spheroidal in  figure, the lateral diameter being the  shortest.
It is  composed of three coats or tunics, the  sclerotic, choroid,
and retina.  The sclerotic is formed of dense Avhite fibrous tis-
sue, and giA^es" to the ball its figure and white color; to it the
muscles are attached.  The  choroid is the vascular coat, con-
sisting  of arteries and veins, and lined interiorly  with black
  How does a reduction of the diameter influence the penetrating power ?  How is the eye-
ball protected ?  What  is the relation of the axes of the orbits to each other? How is later-
al vision obtained in man ?  What is the shape and diameter of the eyeball in man ?  Name
the three tunics of the ball.  Describe the sclerotic.  Describe the choroid.
« 
208          THE THREE HUMORS OF  THE EYE.
Fig. 150.                         Fig. 151.
Blood-vessels of the Choroid Coat.
pigment.   The retina is the nervous coat, and is formed by the
             Fig 152       <•     expansion of the optic nerve.
                                  Fig. 152, a a, the cornea; r,
                               retina; i, iris; e, lens;  m, ante-
                               rior chamber  of  aqueous  hu-
                               mor ; p, posterior chamber;  d
                               r' r, ciliary  body;  v, vitreous
                               humor; o, optic nerve.
                                  The organ of vision  may
                               with advantage be studied un-
                               der three distinct  divisions:
                               1st. The optical  mechanism;
                               2d. The nervous  mechanism;
and, 3d. The appendages.
  The optical mechanism  consists of the cornea, three humors,
the iris, and the screen, or black pigment.  The cornea is shaped
and fitted into the sclerotic like a watch-glass into its case.   It
is composed of a transparent fibrous tissue, and serves to give
a convex figure to the humor which lies behind it.
  The three humors are the aqueous,  crystalline, and vitreous.
The vitreous is largest in quantity, occupying about four fifths
of the bulk of the  eyeball;  the aqueous is the most fluid, and
lies immediately behind the cornea; while the crystalline hu-
mor is the densest, and is situated between the aqueous  and
vitreous humors.
  The aqueous humor is divided into two portions by the iris;
that Avhich lies between the iris and cornea  is called the ante-
rior chamber, and that between the iris and crystalline lens is
called the posterior chamber.
  Where is the black pigment ? Describe the retina. Under what divisions is the eye de-
scribed ? What parts compose the optical mechanism ?   Describe the cornea.  What is its
function?  Name the three humors.  Which is greatest in bulk? Which is most fluid?
Which is most dense?  What is the relative position of each humor? What are the ante-
rior and posterior chambers ?
• 
            THE IRIS, BLACK PIGMENT, AND RETINA.        209

   The^ crystalline humor or lens is double convex in figure, the
posterior surface being the most convex;  it is held in position
by the ciliary ligament and muscle.  The lens is perfectly trans-
Fig. 153.        Fig. 154.       Fig. 155. ■      Fig. 156.
Crystalline Lens.                 Fibres of Lens.
parent, and composed of fibres, the edges of which are dentate
or serrated, like the toothed edge of a saw; the teeth of adjoin-
ing fibres, interlocking with each other, give greater firmness to
the lens.
   The vitreous humor has a density intermediate between that
of the aqueous and crystalline
humors ;  it is held in position,
and the formation of currents
avoided, by the presence of a
delicate  membrane,  Avhich
traA^erses it in every direction,
called the hyaloid membrane.
   The iris  is  placed in  the
aqueous humor, separating it
into the anterior and posterior
chambers.  It is composed of
muscular fibres, some of Avhich  vitreous Humor'showing the Hyalold Meml>raDe.
pass circularly  around the central opening or pupil, Avhile the
others are arranged as radii, extending from the margin of the
pupil to the insertion of the circumference of the iris into the
sclerotic.   When  a strong light falls on the iris the  circular
fibres contract, and diminish the opening of the pupil.
   The black pigment is the inner layer of the choroid or mid-
dle coat; it is the  screen of the eye, on Avhich the humors bring
the images of objects to a focus.
   The retina is formed by the  expansion of the optic nerve, the
portion next the black pigment being the most sensitive.  The
optic nerves do not pass directly from each eye  to the same

  What is the figure of the lens ?  How is it held in position ? What is the composition of
the lens ?  AVhat is the relative density of the vitreous humor ?  What is the hyaloid mem-
brane ? What is the position of the iris ?   Of what tissue is it composed ?  How are the
fibres of the iris arranged? What is the pupil?  Where is the black pigment? What is
the retina ? Which part is the most sensitive ?
                              o
 
210
THE  APPENDAGES OF THE EYE.
side of the brain, but they meet at a short distance behind the
orbits to form the optic chiasm, in AAmich there is a crossing and
interchange of nerve fibres, so that a portion of those from the
right eye pass to  the  same side of the brain, some to the left
hemisphere, and others to the left eye.   Those from the left eye
pass to the left and right hemispheres, and to the right  eye.
There is, consequently, a perfect and free  communication be-
tAveen the eyes, and any cause which affects one eye is almost
certain to produce disturbance in the condition of the other.
   The appendages of  the eyeball are muscles, an exterior mu-
cous membrane, the lachrymal  apparatus,  the lids,  eyelashes,
and eyebrows.
   The muscles of the  ball are six in number; four  pass from
the  apex of the  orbital cavity to be inserted into the upper,
lower, inner, and  outer parts  of the ball: they are called the
                        recti  muscles,  and are designated re-
                        spectively  as the internal,/i external,
                        e,  superior, b, and inferior, c, rectus.
                        The other muscles pass obliquely from
                        the sides of the  orbit, and are known
                        as the obliquus  superior  and inferior,
                        g, while the muscle which  raises the
                  ^y   upper eyelid is called the leA^ator pal-
          ,       ,       pebrse, a.
     Muscle of the Eyeball. •      A  /T77 '             -.      „ ,       .
                          I he mucous membrane of the eye is
called the conjunctiva.   It coA^ers  the cornea, the anterior por-
tion of the sclerotic, the inner surface of the lids, and is contin-
uous with the mucous membrane of the nasal cavity.   The por-
tion of the conjunctiva that passes over the cornea is perfectly
transparent and invisible, except when the vessels are  injected
by inflammation.
   The lachrymal apparatus consists of the lachrymal gland, its
ducts, and the nasal duct.  The gland is placed in the upper
and  outer  part of the  orbit,  and furnished with a number of
small ducts, by which  the secretion is delivered  on the con-
junctival membrane of the ball.  The nasal duct commences at
the  inner angle  of the eye,  and terminates in the nasal cav-
ity_____________________
  What is the optic chiasm ?  AVhat disposition is made of the nerve fibres from the retina
of the right eye—from the left eye?  AVhat are the appendages of the eye?  How many
muscles are attached to each eyeball ? Give the position of each of the recti muscles. What
are the oblique muscles ? What is the name of the mucous membrane of the eye ? What
parts does the conjunctiva cover ? What is the effect of inflammation on the transparency
of the conjunctiva ?  What parts compose the lachrymal apparatus ? Where is the lachry-
mal gland? How is its secretion delivered on the conjunctiva ?  Where is the nasal duct ?
 
THE ACTION OF THE  HUMORS AND IRIS.         211
   The lids are composed of skin externally, and mucous mem-
brane internally.  The upper lid  is provided with a disc of
cartilage, Avhich gives to the lid its figure.   On the edge of
both  lids there is a row of glands, which are placed between
the hairs or lashes of the lids; inflammation of these glands is
very common, and is generally known as sty.
   The eyebrows are formed  of short hairs, which are arranged
in such a manner as to direct the perspiration as it Aoavs doAvn
the forehead on each side, and prevent its passing into the eyes
and interfering with vision.
                     LECTURE  XXXIX.
                   THE ACTION OF THE EYE.
 The Function of the three Humors.— The Action of the Iris.—Adjustment
  for Difference of Distance of different Objects.—Method of Correction
  of Spherical Aberration. — Correction  of Chromatic Aberration.—^-Ac-
  tion of black Surfaces on Light.—Action of the Ocellus.—Action of the
  Compound Eye of a Fly.—Action of the Eye in the Higher Animals.—
  Action of the Muscles of the Eye.— Of the Lachrymal Apparatus.— Of
  the Lids, Lashes, and Eyebrows.—Longsightedness  and Shortsightedness
  described. — Method for relieving them. — Cataract described. — Opera-
  tions for its Relief.—Strabismus.—Peculiarities of the Optical Apptaratui*.
  in the Lower Animals.— Constitution of Areolar Tissue.—Adipose Tis-
  sue, its Formation, and Tenacity of certain Positions.—Description of
  the Skin.
  The action of the eye may be studied under  three divisions:
 1st. That of the optical portion; 2d. Of the  nervous portion ;
 and, 3d. Of the appendages.
  The  humors of  the eye, taken together, form an achromatic
 combination, Avhich brings the rays falling  on the cornea  to a
 sharp focus on the black pigment.
  The  iris regulates the quantity of light passing into the in-
 terior  of the ball.   When the light is intense the pupil con-
 tracts, and when it  is feeble it expands, so allowing  a greater
 or lesser number of rays to enter the organ.
  The  adjustment for variation in  the distance of various ob-
 jects is accomplished by the ciliary muscle and ligament, Avhich
alter the distance  of the lens from the black pigment, and also
change its curvature by compressing it at the circumference.
  What is the composition of the eyelids ?  Where are the glands of the lids ?  What is sty ?
What is the function of the humors of the eye? What is the  action of the iris ? How is
the adjustment for variation in the distance of objects obtained? 
212             ACTION  OF DARK SURFACES.
  The correction for spherical aberration  is accomplished by
the varying density of the different parts of the lens, and the
contraction of the iris, which reduces the diameter of the beam
of light entering the eye.
  In order to understand the function of the nervous  mechan-
ism, we must first examine the action of black surfaces on light.
Franklin found that if small pieces of cloth, of various shades
of color from white to black, were placed on snow on a clear
winter's day, they absorbed the sunlight, and melted their way
to different depths in the  snow.  The  colors  he used were
black, dark blue, pale blue, green, purple, red, yellow, and other
shades, up to a  pure white.  In a short time  the black had
passed out of reach of the sunlight; the dark blue was almost
as deep in the snow, and the others had sunk to a less extent
as their color was lighter, the white cloth remaining on the sur-
face.   Sir Humphrey Davy made a  similar series of experi-
ments  with pieces of colored copper, each one inch square, and
of the  same weight and density; one was black, one blue, one
green,  one red, one yellow, and one white.   On  the middle of
the under surface a small portion of a wax cement, that melted
at 76°, was placed.  The strips were then placed on a piece of
board painted white, and exposed equally to the direct rays of
the sun.   After a short time the wax on the black plate com-
menced to melt, and the others followed in the order in which
they have been  mentioned; but the white  strip showed no
tendency to melt its wax until that on the black one was en-
tirely fluid.
  In the lowest grades of animal life, we find that the ocellus,
or minute eyes of animalcules, consist of a nerve  which term-
inates  in  a  loop covered with black  pigment.   In such crea-
tures, the light, falling on the ocellus, is converted into heat, and
the animal feels its way to the side of the vessel which is most
perfectly illuminated, or hides in some dark recess to rest, its
movements being guided by the  variation  in the  temperature
of the  ocellus.
  Passing a  little higher in the scale, we reach  the compound
eyes of insects, such as the fly, in which the cornea is composed
of a vast number of small hexagonal cornese, which are  the
bases of an equal number of cones, the apices of which meet at
the optic nerve.   A filament of the nerve passes into the apex

  How is spherical aberration corrected ? Describe Franklin's experiment. Why did the
black pieces of cloth sink to the greatest depth ? What is the simplest form of eye ?  How
does the ocellus act? Describe the compound eye of the fly. How does it act ? 
ACTION OF THE APPENDAGES.
213
 of  each cone, and is covered AAuth black pigment, so that the
 creature can not only feel the presence of the light, but can also
 determine its direction, and the outline of the luminous object.
   In the perfect eye of the highest grades of animals the princi-
 ple of action is the same.   The optical mechanism brings the
 rays  to a focus on the  black pigment, Avhere the image of light
 is converted into a heat picture, and, as such, felt by the term-
 inal tubes of the optic nerve, which abut in infinite numbers
 against the black pigment, and, passing to the brain, convey to
 it the impressions they have received in the pigment.
   The  appendages may be  divided into the  motive and pro-
 tective.  The first give to  'the ball its movements, the recti di-
 recting it respectively  upward, downward, to the right, and to
 the left.  The oblique muscles rotate it on its axis, and aid in
 giving to the eye the variable expression of which it is capable.
   The lachrymal gland furnishes the moisture A\Thich preserves
 the conjunctiva in a transparent state.   The secretion is equal-
 ly diffused over the anterior surface of the eye by the lids first
 touching at the outer angle, so as to sweep the fluid furnished
 by the  gland OA7er the  surface of the ball, and Avash all dust or
 other foreign substances to the inner angle, where they are con-
 Areyed by the nasal duct to the nasal cavity.
   The eyelashes aid in protecting the eye by causing the sud-
 den closure of the lids when  any object touches them; the
 eyebroAvs, as we have previously stated, direct the perspiration
 as it flows down the forehead, and prevents its passing into the
 eyes.
   Of the diseases Avhich affect the eye, none are of greater in-
 terest than long and shortsightedness.   The first exists in old,
 and the second in young people.  In the earlier period of life,
 the humors of the  eye, as Avell as all the tissues of the body,
 are distended Avith moisture, consequently the ball is bulged
 forward, the convexity  of the cornea increased, and the focus of
 the eye shortened, so that  the image falls  in front of the black
 pigment; the object must therefore  be approached close to the
 organ in  order to  throAV the focus backward, and produce a
 sharply-defined image on the pigment.   In old age, on the con-
 trary, the humors are deficient in quantity, the ball is less dis-
  What is the method of action of the eye in man and the highest grades of animals ?
 What is the function of the  recti muscles? How do the oblique act?  What is the use of
 the lachrymal secretion?  Where do the eyelids touch first?  How is the lachrymal secre-
tion finally disposed of? AVhat is the function of the eyelashes? What is the object of the
eyebrows?  At what period  of life does longsightedness appear?  When does shortsighted-
ness occur? AVhat is the cause of shortsightedness—of longsightedness?  Where does the
focus fall in shortsightedness? 
214       LONGSIGHTEDNESS AND  SHORTSIGHTEDNESS.

tended, the cornea flatter, and the focus falls beyond or behind
the black pigment;  the object must consequently he placed at
a greater  distance from the eye, in order to bring it to a sharp
focus on the pigment.  This condition is therefore  called long-
sightedness.
  Shortsightedness  may be relieved  by  the  use  of concave
lenses, which  cause  the rays to diverge as they enter the or-
gan, and  so throw the focus farther back; longsightedness, on
the contrary, requires the use of convex lenses, which  converge
the rays,  and, bringing  the focus  forward, cause it to fall on
the pigment.   In the selection  of glasses, the lens for  each eye
should be chosen separately, for there  is usually a difference in
the foci of the eyes; and if lenses of the  same focus  are used
under such conditions,  one  eye  is  apt to be strained, and more
or less injury of the organ produced.
  The various tissues of the eye are liable to  rheumatic, ordi-
nary, and specific inflammations, Avhich should be immediately
placed in the care of an experienced physician; for it is to be
remembered that the eye is very delicate, and inflammation, es-
pecially when produced by some specific cause, is apt to result
in its sudden destruction.
  In certain families there  is a predisposition to the formation
of an opacity of the lens, called cataract,  in which it becomes
perfectly  opaque, and the passage of light to the interior of the
eye being cut off.   As long as the disease exists in one eye
only, it is best to let it alone; but when it exists in both lenses,
and useful vision is lost, an  operation may be performed, which,
in the majority of cases, results in affording the patient a very
fair degree of vision.
   The operations for cataract consist in either passing a suita-
ble instrument through the cornea, and depressing the  opaque
lens out  of the axis of vision,  or in making an incision in the
cornea, through which  the  lens is  extracted.   Inflammation is,
of course, produced, and loss of both eyes may follow  an opera-
tion  on  one.  Such treatment ought, therefore, never to be
adopted until all useful vision  is lost.
   Squinting, or  strabismus, is  caused by an undue contraction
of the external  or internal rectus muscle; it  may be relieved
by catching the  muscle on  a suitable hook, drawing it forward,
  Where does the focus fall in longsightedness ?  What class of lenses are required in short-
sightedness ? How do they act ?  What lenses relieve longsightedness ?  How do they act ?
Why should  the lenses be chosen separately  for each eye ?  What is cataract ?   How does
it produce blindness ?  Under what circumstances should an  operation be performed ?  De-
scribe the operations for cataract. AArhat is  strabismus?  How may it be relieved? 
               COMPOSITION OF  AREOLAR TISSUE.            215

and  severing it Avith a pair of scissors.  The operation is not
ahvays successful, for the eye is sometimes turned in the oppo-
site direction.
  The lower  animals present various peculiarities as regards
the  eyes, among which  Ave  may mention the  chameleon, in
Avhich the eyes are placed on stems or stalks, and are capable
of independent motion.   In the carnivora the  eyes are very
large compared with the size  of the animal, and the exterior
Avail  of the orbit  is composed of ligament, which allows the
eyeballs to be pressed outAvard, giving to the creature a pecul-
iarly ferocious look. In the herbivora, on the  contrary, they
are small, as  in the elephant.   In the burroAving  animals, as
the mole, they are very minute, and in fishes which inhabit the
Avaters of caA^es they are reduced to a rudimentary condition.
In birds there is a third eyelid, Avhich passes transversely across
the eye, to Avhich the name of membrana nictitans is given.
  In enumerating  the  organs of
the body, the areolar or connectiAre
tissue, and the skin, were mention-
ed.  The  areolar tissue is composed
of yellow elastic and white inelas-
tic fibres, which interlace with each
other in every direction, to form a
tissue filled with areolae  or spaces.
  When  the  areolar tissue is  em-
ployed for the purpose of connect-
ing muscles or retaining organs in
their proper position, it  is loosely
Avoven, so that the areolae, or cells
formed by the fibres, are of consid-
erable size; but when it is employed to form membranes, it is
then closely woven, and  the cells or spaces disappear.
  The connective, or, as it is often called, cellular tissue, lies be-
tween all the muscles  and organs of the body, and there is a
perfect communication among  the spaces or cells, as is demon-
strated by the fact that  when the ribs are fractured, and the
lung wounded so that  the air passes into the cellular tissue, it
quickly finds its way betAveen all the organs of the body, and

  What is the peculiarity in the eyes of the chameleon ?  How do the eyes of the carnivora
compare in size with the herbivora? What  gives to the carnivora their ferocious appear-
ance?  AVhat is the peculiarity in the eyes of burrowing animals like the mole?  AVhat is
the membrana nictitans ?  AVhat is  the composition of areolar tissue ?  Under what circum-
stances does the texture of connective tissue vary?  How is the communication of the cells
of areolar tissue demonstrated ?
 
216
THE  AREOLAR TISSUE AND SKIN.
Fig. 160.
the areolae or spaces become filled -with the gas, and the body
distended to an unnatural and dangerous degree, so that incis-
ions in the skin have to be made in order to relieve the sufferer
                  In the cells of the areolar tissue fat globules
                are deposited, forming the fatty or adipose tis-
                sue.  By this device provision is made for  a
                very considerable deposit of fat, without inter-
                fering with the action of any organ.   There
                are, however, certain localities in AAmich fat re-
                mains in considerable  quantity, even to the
                last point of starvation;  among these we may
                mention the orbits as most prominent, a cer-
                tain proportion being required to form a cush-
                ion for the  eyeball, in order to give it proper
                support.
                  The skin we have already described in part
when speaking of the organ of touch.   It consists of two lay-
ers, the external epidermis or cuticle, formed of epithelial cells,
which are worn away by  contact with  hard  external sub-
stances : it is reproduced from the inner layer, called the cutis
vera (true skin), or derma.
  The derma  is  composed of areolar  tissue, blood-vessels,
nerves, glands, and  hair follicles, all of  which have been  de-
scribed in previous  lectures.  The  function of the  skin is to
form -an external covering to the  tissues of the body, and pro-
tect them from the  action of air, water, and external violence,
while the areolar  or connective tissue holds each organ in its
proper place, and retains the skin in contact with the tissues it
protects.
Adipose Tissue.
 How is fatty or adipose tissue formed ? Of what part of the body is the fatty deposit most
tenacious ? Of what parts is the skin composed ?  Describe the derma. What is the func-
tion of the skin ? 
  SECOND  DIVISION.
DYNAMIC  PHYSIOLOGY.
                       LECTURE XL.
                        REPRODUCTION.
 Reproduction of Plants. — Conditions  requisite for Germination and
   Growth.—Reproduction of Animals.— Organs of Reproduction in Ovi-
   parous and Viviparous Animals.—Menstruation.— Corpus Luteum.—
   Semen, its Composition  and Properties.—Impregnation.—Nourishment
   of Foetus.—The Placenta.— Quicken ing.—Miscarriage.—Parturition —
   Change in Respiratory Function at Birth.

   Having completed  the study of man as an  individual, Ave
 now pass to the second division of Physiology, Avhich Professor
 Draper has specified as Dynamic Physiology.   In  this branch
 the phenomena of reproduction  are of special importance;  we
 shall, therefore, first devote  as much  space  as possible to their
 consideration.
   Plants are reproduced either  by the ordinary reproduction
 of cells, or by inflorescence and the formation of seeds.   Flow-
 ers are of two kinds, male and female.   The first forms a fine,
 dust-like powder called pollen,  which  is brought in  contact
 with the seed vesicles of the female flowers either by the winds
 or through the agency of insects.  Without  the access of the
 pollen the female floAvers are sterile, and  neither fruits nor
 seeds are produced.
   During the inflorescence of plants a considerable amount of
 heat is evolved, and carbonic acid at the same time produced,
 so that there  are periods in the life of a plant AA'hen it takes on
 an action similar to that in animals, becoming an oxidizing in-
 stead of a deoxidizing  agent.
   When the perfect seed is produced, its vitality  is dormant
 until it is placed under proper conditions for development into
 a plant.   These are moisture, air, Avarmth, and  darkness; but
  How are plants reproduced ?  What is the pollen ? AArhat is its function ? What is the
effect of inflorescence on the temperature? What gas is produced during inflorescence?
What conditions are required for the development of a seed? What are the conditions re-
quired for healthy growth in a plant ? 
218         OVIPAROUS AND VIVIPAROUS ANIMALS.
the moment that it has fairly sprouted it requires a free expo-
sure to light in order to develop in a proper manner, and pro-
duce green leaves, and the gum, and other  materials  out of
Avhich  the tissues of plants are constructed.
                  Among animals, many of the lowest forms,
                such as the hydra, are reproduced by germina-
                tion, or budding, a  neAV creature  sprouting
                from the side of the parent, and being detached
                as soon as it has reached a sufficient degree of
                perfection to take care of itself.
                  The great majority of animals, like plants,
                originate in the conjunction of male and female
   Hydra budding.       »   .in   in   ' 1,"       'u. \ 1
                germs, the female furnishing a  suitable ovum
or egg, Avhich  must be vivified by the  male, in order that it
may develop into a perfect form resembling one of the parents.
  If the female retains the ovum within her body until  it is
perfectly developed into a living representative of its  species,
and then brings it into the world alive, it is  said to be vivipa-
rous.   If, on the contrary, the embryo is  ejected in an imper-
fect form, as an egg, which has to be subjected to the influence
of elevation of temperature for a given period before a living
creature is produced, it is called oviparous.
  In the oviparous class the testes of the male  are usually in-
closed  Avithin the body, and the female is provided Avith an
ovary  and  an ovipositor, in which the egg receives its external
hard coating or shell.
  In the viviparous animals the testes of the male are exterior
to the  body, and placed in a suitable envelope of skin called the
scrotum, while the female  is furnished with  a pair  of ovaries,
and a  uterus or Avomb, in which the embryo is retained until
it is perfectly developed, and able to live and move about  free-
ly.   For the proper nutrition of its young the female is farther
provided with mammae or teats, which furnish milk suitable
for the wants of its offspring.
  In both oviparous and  viviparous animals, the  appearance
of the  power of reproduction marks the end of the period of
growth, very few animals  commencing to reproduce their spe-
cies until they have themselves reached a perfect state of de-
velopment.  In the lower  animals the appearance of the repro-
  Describe the methods of reproduction of animals by germination. How are animals gen-
erally reproduced ?  What is meant by viviparous and oviparous animals?   AVhat is the po-
sition of  the testes in the oviparous creatures? Where does the  egg receive its shell in the
oviparous female ? What organs form the reproductive apparatus in the viviparous female ?
At what period of life does the power of reproduction appear?
 
              THE UTERUS AND  ITS APPENDAGES.          219

ductive period is marked by the condition called heat, Avhich
comes on, in the majority of the higher animals, once or twice
in the course of the year; but in small animals, Avhich are not
provided with any effectual means of defense, it occurs more
frequently.
   In  the human female this condition is called menstruation,
and it occurs in healthy women regularly every four weeks.
It is marked by congestion of all the organs connected with re-
production, including the mammae, and the discharge  from the
uterus of a sanguineous fluid.
   At each menstrual period an ovum is discharged from the
ovary, a a, which is, in the human female, attached to the later-
al ligaments c c, that holds the uterus, u, in its proper position
in the pelvic  cavity.  The uterus is provided Avith a singular
                            Fig. 162.
Uterus and Appendages.
apparatus  on each side, called the Fallopian tube,/ o', which
terminates in a free fimbriated extremity, e, that curves over to-
Avard the ovary, and, grasping it at the time the ovum is dis-
charged, conveys it into the cavity of the womb.  In Fig. 162,
d d, d d, g g, are other ligaments of the womb; h is its neck;
n, the opening or os uteri, the letter being  placed on the  up-
per part of the vagina.
  The  escape of an ovum from  the ovary causes  a wound,
Avhich gradually heals and leaves a scar, which remains during
life if the  ovum  is impregnated, and is  called the corpus lute-
um*   If the ovum is not impregnated  the scar  gradually dis-
appears, and Avhile it exists is called  a false corpus luteum.
  When it has reached the uterus the unimpregnated ovum is
discharged, together with blood, epithelial cells, and  the secre-
                * See Dr. J. C. Dalton on Corpus Luteum.
 What is meant by heat in animals ? How often does it occur ? What is  menstruation ?
AVhere is the ovary in the human female ?  AA7hat is the Fallopian tube ? AVhat is the cor-
pus luteum ? 
220           THE TESTES AND THEIR SECRETION.
Fig. 163.
                          Corpora Lutea.
tions  of the parts.   The menstrual fluid differs from ordinary
blood in that it does not form a coagulum or clot, unless there
is a great excess of blood in the secretion.
                                  In the  male the germs are
                                prepared by the testes.  The
                                fluid formed is  called  semen,
                                and consists of an albuminous
                                liquid, in  which minute cells,
                                called spermatozoa, are in act-
                                ive movement.   The  sperma-
                                tozoon is a caudate cell, shaped
                                like  a  tadpole with a  long
                                tail; it is  about 10 o o o^n of an
                                inch in width, and siroth of an
                                inch in length,  and continues
                                to move about vigorously as
                                long as it retains life.
                                  From the fact that  the cor-
                                pus luteum  produced by an
                                impregnated ovum is different
                                from an ordinary false corpus
                                luteum, it is probable that the
                                vivification  of the  ovum  oc-
                                curs before it leaves the ovary,
                                so that the spermatozoa must
find their way through the uterus and Fallopian tube in order
to accomplish that result.
  Leaving the ovary, the  impregnated ovum  passes  slowly
down the Fallopian tube  to the uterus, and is  attached to its
 How  does the menstrual fluid differ from ordinary blood ?  What is semen ? Describe
the spermatozoa.  Where is the ovum impregnated?  What facts show that impregnation
occurs in the ovary?  Describe the course of an ovum after it is impregnated.  How is the
ovum disposed of on reaching the uterus ?
The Testis. 
             LNTRA-UTERINE GROWTH AND BIRTH.         221

Avails near the  opening of the tube.  It steadily increases in
size until a sac  filled Avith fluid is formed, on one side of Avhich
the embryo commences to assume its proper figure.
  In  the earliest stage  of development, the materials for the
nutrition of the  embryo are obtained from the yolk of the
ovum, but soon after it  reaches the cavity of the uterus it de-
rives  its nutriment from tuft-like  vessels which attach them-
selves to the wall of the womb.   These finally become consol-
idated, forming a distinct organ  called the placenta, by means
of which the foetus (as the child in utero is called) is nourished
until  the time of birth.
  With the increase in  the bulk of the foetus, the uterus grad-
ually rises out of the pelvic caAdty, and toward  the close of the
period of gestation occupies the  abdominal cavity, interfering
seriously with all the functions of the system.
  Quickening, or the first movements of the child, are noticed
in the eighteenth week, and  delivery occurs about 280 days
from  the time of impregnation.   This is, however, liable to va-
riation, children being often born in an imperfect condition by
a miscarriage.   If the child is in the eighth month it Avill live,
and seven months' children have been often successfully reared.
Some women carry their children longer than forty Aveeks, and,
according to the French laws, a child is legitimate if born Avith-
in 300 days.
  The act of parturition commences with slight contractions of
the fibres at the base of the uterus, Avhile those at the mouth
and neck are  relaxed.   After  a  short time, the membranes
Avhich form the water-cushion on Avhich the  foetus rested are
ruptured, the waters escape, and the child is  born, the head
being usually the first part to come in contact with the exter-
nal air.
  The contact of the body of the child Avith the air seems to
cause pain, for it gives utterance to a cry, which marks the first
entrance of air  into its  lungs.  At the same  time, the Aoav of
blood is directed from  the placental vessels to  those organs,
and respiration is in a moment changed from the aquatic to the
aerial form.
  How  is the embryo nourished in its earliest stages ? What is the placenta ? What is the
position of the uterus at the close of the period of gestation ? What is quickening, and
when does it occur ?  What is a miscarriage ?  What is the French law regarding legiti-
macy ?  What is parturition, and how is it conducted ?  What part  of the child is usually
born first?  What is the effect of the contact of air with the body of the child ? How is
the function of respiration changed at birth ? 
222                   THE FIVE PERIODS.
                      LECTURE XLI.
                 THE  COURSE  OF HUMAN LIFE.
The five Periods in the Life of an Individual.—Size of the new-born In-
  fant.—Rate  of Growth.—Average Height of Adults.—Maxima and
  Minima of Height.— Weight at Birth.—Average Weight of Adults.—
  Period  of maximum Weight. — First Attempts at articulate Speech. —
  Relation of the vegetative and intellectual Powers to each other.—Evi-
  dences of their Influence  on  each other. — Decline of Intellectuality. —
  Average Duration of Life.—Mortality at different Periods.—Influence
  of Sex and Stature on Mortality.—Instances of great Longevity.—Ap>-
  proach of Death.—The Fades Hippocratica. — Interstitial Death.—
  Period of Repair.—Sleep.—Amount of Sleep required at different Peri-
  ods of Life.— Order in which Sleep subverts the Senses.
  The life of man may be divided into five periods:  1st, the
foetal; 2d, the  infantile;  3d, the adolescent;  4th, the  adult;
and, 5th, that of old age.  The first period we have examined
in the previous lecture as far as our space would admit; we
therefore now pass to the consideration of the infantile  period.
  The average length  of the newly-born  male  infant  is 18^
inches, while that of the female is 18|-  During the first five
years the annual rate of growth is rapid; but it  gradually be-
comes less and less, until a uniform annual  rate is established
of about 2^  inches, which continues  from the fifth to the six-
teenth year;  in the seventeenth year it is about 1| inches, and
during the. eighteenth and nineteenth about one inch.
  The full growth is  usually attained at  about the  age  of
twenty-one, but many persons continue to grow to the twenty-
fifth year.  The average height of an adult, according  to  Que-
telet, is  5 feet 8 inches.  He also states that the maximum is
8 feet  3  inches, and the minimum 1 foot 5 inches.
  At birth boys are heavier than girls; the  average weight be-
ing 6| lbs., the maximum  121, and the minimum  2^ lbs.   Dur-
ing the first week of infantile life the weight diminishes slight-
ly, owing to  the change to  the aerial form of respiration; it
then increases rapidly,  tripling in the first year, doubling that
  What are the five periods in the life of an individual?  What is the length of a new-born
infant ?  At what period is the rate of growth most rapid ?  What is the rate from the fifth
to the sixteenth year ?  At what age is  the full growth attained ?  What is the average
height ?  What are the maxima  and minima of height ? What is the average weight at
birth?  What are the maxima and minima of weight at birth?   What change occurs dur-
ing the first week of infantile life ? 
           THE VEGETATIATE  AND  INTELLECTUAL LIFE.       223

 in  the folloAving six years, after Avhich the rate becomes less
 and less, the maximum being reached at the  fortieth year;  it
 then remains nearly stationary until the sixtieth year, when it
 commences to diminish until death.
   The average Aveight of men betAveen 25 and 40 is about 140
 lbs., and of Avomen 120 lbs.: the healthy maxima and minima
 in  men are  216 lbs. and 108 lbs.; in Avomen, 206  lbs. and 87
 lbs.
   As the human being develops in stature and Aveight, the in-
 tellectual poAvers also increase in perfection.  At its entrance
 into the world, there is no other mammal so utterly dependent,
 so  weak, and void of intellectual power as an infant.  The or-
 gans of special sense  seem to be perfectly developed, but they
 are not employed, and the future hero lies in his  cradle a help-
 less mass of imbecility, scarcely shoAving his existence save by
 cries of pain, and spending his days in eating  and sleeping.
   Gradually, as  it increases in size and weight, the infant be-
 gins to obtain the use of its special senses, and, overcoming the
 state of stupefaction produced by the numberless  objects it met
 on its entrance into the world, it commences to recognize those
 by whom it is surrounded, and rewards  the anxious care of its
 mother with sunny smiles.
   During this early period life is absolutely vegetative, but at
 about the twelfth or eighteenth month the infant  commences
 to gain the power of articulate speech, which seems to mark the
 epoch at which the mind obtains the ability to concentrate it-
 self on one object or sensation.  As the age  advances the in-
 tellectual power rapidly increases, until at the period of puber-
 ty  it predominates over the vegetative life, Avhich  up to that
 time is in the ascendant.
   The mental and intellectual powers reach their zenith at
 about the fiftieth  year.  They are most intimately connected
 Avith the physical  condition  of the body, and the reaction of
 the mental and  animal individualities on each other are de-
 monstrated by the facility Avith Avhich we select the intelligent
 from the imbecile by  the expression of their faces, or read the
 thoughts and ideas Avhich illuminate the countenance before
 they assume the  form of speech.
  AVhen is the maximum of weight attained? When does the period of decline commence?
 What is the average weight of adults?  What are the maxima and  mimima? What is the
condition of the new-born infant ? At what period is the power of articulate speech gained ?
What change in the mind occurs at the same time ?  What is the relation of the vegetative
to the intellectual powers at the different periods of life?  At what age does the intellect
reach its maximum ? What are the evidences of the influences of the physical and intel-
lectual powers on each other? 
224
DURATION OF  HUMAN LIFE.
  As soon as the intellect has reached its maximum the period
of decline commences, and not only the special senses, but also
ideality and reason, begin to fail, the passions lose their intens-
ity, ambition its sway, and as old age gradually steals upon the
great statesman  or humble laborer, they  fall alike into  the
same condition of mental imbecility which they presented on
their entrance into the Avorld, every species of exertion becom-
ing irksome, memory more and more obtuse, the last acts of an
eventful life being the first to fade away, until at last only the
recollections of the associates and joys of childhood are retain-
ed, and the child of a hundred years dozes  quietly and dreams
away his life, waiting for the death-sleep to close his eyes  for-
ever.
  The average duration of life  is about 33  years, the mortality
being greatest in its earlier  period.  About 22 per cent, of the
births are lost before they r*each the close of the first year, and
37 per cent, before they reach the sixth,  and  at twenty-five
half the births are lost.
  The ratio of mortality is  greater in cities than in the  coun-
try; it also increases among females between 14 and 18, and
during the period of child-bearing, and among men between 21
and 26.  Stature also possesses an influence, tall men generally
being short-lived.
  Geographical position  causes a Awiation  in the ratio of mor-
tality, being 1 to 41 in Northern Europe, 1 to 40^% in Central
Europe, and 1 to 33^  in  Southern  Europe.   The  greatest
number of old people is found in the temperate zone, which
furnishes also the largest proportion of recorded instances of
longevity, of which the following may be mentioned as being
well authenticated: Margaret Patten, 137 years;  Thomas Parr,
152; John  Room, 172 ; Peter Torton, 185.
  The following tables  show the proportion of persons in  dif-
ferent communities that reach the age of  100 years, and also
the average mortality in  some of the great  cities :
  Number who are 100 and upward in a population of 20,000:
         England...............................................................   0-34
         Wales..................................................................   0-50
         United States, freemen.............................................  1-02
            "   "   slaves...............................................  14-10
  When does the intellectual power begin to decay?  Do the  impressions of the earlier or
later period of life fade first ? What is the average duration of human life ? At what peri-
od is the mortality greatest?  What proportion of births are lost at the close of the first
year ? What at the sixth—the fifteenth—twenty-fifth ? What differences exist in the ratio
of mortality in the different sexes ?  What is the influence of stature on the rate of mortal-
ity ?  What is the influence of geographical position ?  Mention some of the instances of the
greatest longevity. 
THE  APPROACH OF DEATH.
225
                 Mortality one in
England.................................. 51
Wales..................................... 69
Philadelphia............................. 4G
Manchester.............................. 44
London................................... 40
New York*............................... 38
                 Mortality one in
Charleston...............................  37
Berlin.....................................  34
Paris......................................  32
Naples....................................  28
Rome......................................  25
Vienna....................................  23
   The longest life must at last terminate, and every one must
sooner or later pass  over  the bridge of death to join his fore-
fathers  in the unknoAvn land.   We instinctively shrink from
the final act,  and speak of it as the agony, dreading it  not so
much on  account of the pain suffered  as of the gloom and so-
lemnity of the grave, and the uncertainty attending our  fate in
the night of eternity.
  ^ Death rarely comes to us by the slow approaches of old age;
his onslaught is sometimes sudden, and life is overAvhelmed be-
fore the approach of danger is even suspected.  In such a vio-
lent, sudden physical annihilation there can be but little pain,
for the face of the soldier who has been cut doAvn in a moment
bears the expression that  Avas flitting across  it at the time the
fatal bullet touched the vital spot, and retains even in death
the impress of the exultation of victory or  the despair of de-
feat.
   Excepting  the  comparatively small  number of instances of
death by  accident and old age, Ave may regard it as usually oc-
curring from  disease, which is more or less prolonged, so that
the powers of life are wasted, and sensations and senses dimmed
before dissolution commences.   The approaching termination
of the sufferings of the dying man have been so Avell portrayed
by the pen of Hippocrates that even  modern science accepts
his description as being unsurpassed, and gives to the peculiar
physiognomy  of death the designation of the " Facies Hippo-
cratica."   It is ushered in " by the patient shoAving a disposi-
tion to lie on  his back, his arms stretched out, his legs hanging
down, and a tendency to slide down in the bed.  The motions
of the hands are  sometimes uncertain, and the patient picks at
the bedclothes as though  he Avas  attempting to remove small
objects from them ; the countenance is  changed; the lips hang
relaxed and cold; light becomes  unbearable; the brightness
of the  eyes is lost, and they become overspread Avith a  misty
cloud; the balls shrink into  their sockets;  the nose is  sharp-
  * One cause of the greater mortality of New York is the enormous number of emigrants
arriving at that port.
  How does death usually make its approach ?  What is the Facies Hippocratica ?  De-
scribe the symptoms and movements that attend the approach of death. 
226         TISSUES  ARE REPAIRED DURING SLEEP.

ened; temples hollow; ears cold and Avhite; and the features
pinched, and of a greenish or lead-colored hue."
  Though death is generally regarded Avith such intense feel-
ings of repugnance, it is nevertheless essential to the well-be-
ing of all living creatures, for the processes of life can not be
accomplished without the continual  destruction of the tissues
composing the body.  To these phenomena the designation of
interstitial death has been  given ■ it commences Avith the first
breath and continues throughout life, but is repaired  as fast as
it occurs by the organs of nutrition.  During the early periods
of life repair is more rapid than waste; the body consequently
increases  in  size and weight, until  finally  an equilibrium is
reached, Avhich lasts_for  a few  years,  Avhen the Aveight com-
mences  to decline, the waste being more rapid than the  repair
in the systems of old people.
  Reparation of tissues take place chiefly during sleep.  In in-
fancy and adolescence, when the body  is growing rapidly, the
greatest portion of our time is spent in sleeping, so  that the
construction  and increase of tissues may advance Avith as little
interruption  as possible.   When the adult period is  reached,
the average  amount of sleep is about eight hours  in  eATery
tAventy-four,  though many people need  only four or five, or
even less.  As old age approaches, and the recuperative pow-
ers  of the system decline, a far greater amount of sleep is  re-
quired.
  The approach of sleep is marked by the gradual loss  of vis-
ion, then  the sense of smell is blunted, hearing becomes more
and more  obtuse, the sense of touch is obscured, the muscles
are relaxed, and the pulsations of the heart and the respiratory
movements become less rapid and more regular.   The deepest
sleep is in the earliest  part of  the night, and it gradually be-
comes lighter on the approach of day, Avhen the mind regains
its consciousness in the reverse order to that in Avhich it was
lost.
  When  the system does  not  obtain  a  sufficient  amount  of
sleep, either  on account of care, anxiety, or overwork, the great
nervous ganglia become irregular in  their action, the  functions
of the body  are disordered, digestion is imperfect, and the tone
of all the  organs and tissues steadily declines.  But  an over-
indulgence in sleep is almost equally injurious, for the nervous
 What is interstitial death? At what time does repair take place most rapidly in the sys-
tem ?  At what period do we sleep most? What is  the average amount of sleep required
by adults? Why  do old people sleep so much? What is the order in which  the senses are
subverted by the approach of sleep ? At what time is  sleep the most profound ? 
THE  DISTRIBUTION OF PLANTS.
227
system becomes less sensitive, the moral and intellectual facul-
ties are blunted, and all the functions  of the  system are con-
ducted in an imperfect manner, and some eA^en think that con-
tinued OA^er-sleeping aatII produce such serious  diseases as luna-
cy and idiotcy; but it is probable that in such cases the tend-
ency to oversleep is merely a symptom of the approach of the
disease.
                      LECTURE XLII.
INFLUENCE OF EXTERNAL AGENTS ON THE PHYSICAL AND INTEL-
                 LECTUAL CONDITION OF MAN.
Distribution of Plants.— Conditions which Control their geographical Po-
  sition.—Nature of the Boundary-lines formed.—Influence of Ocean Cur-
  rents on Climate. — Distribution of Animals. — Influence of Physical
  Agents on Man.— Theories regarding the Origin of the Human Race.—
  Explanation of the Production of Races.—Variation in the Color of Men.
  —Measurements of the Skull.— The Facial Angle.

   It is  a well-knoAvn fact that different  A^egetable products
are found on different parts of the earth's surface.  The condi-
tions which  control the distribution of plants are chiefly heat
and moisture;  and, by examining into the causes which influ-
ence these conditions, Ave find that there is not a single physical
agent that does not possess more or less poAver in determining
the geographical distribution of every species of plant.
   If Ave  trace on the globe the lines which mark the limits of
groAvth  of any plant, Ave find that they do not follow the par-
allels of latitude, but  pass above and below them to an extent
equal to ten or even tAventy degrees.  These curves are partly
due to the influence  of variation in  elevation of the surface
above the level of the sea, but  chiefly to Avinds and  the  cur-
rents in  the  oceans, Avhich  convey enormous masses of warm
water from tropical to northern regions, and modify the temper-
ature to  such an extent as to produce a climate milder than that
of other countries  Avhich  are  much farther south, but do not
enjoy the same advantages.
  The conditions which influence the  distribution of plants
also determine that of animals, confining them to certain local-
ities, beyond the boundaries of A\Thich they can not pass but at

  What are the conditions that control the distribution of plants ?  What is the nature of
the lines that bound the distribution of various plants? What are the agents that produce
these curvatures ?  How do the ocean currents modify climate ? 
228       INFLUENCE OF  PHYSICAL AGENTS ON  MAN.

the risk of destruction  from various physical agents.  Certain
species  are  more Avidely scattered than others; but they  are
few in number, and are almost all included in the list of crea-
tures which are  domesticated by man, either for purposes of
pleasure or profit.
  As physical agents determine the characteristics and distri-
bution  of plants  and animals, so also they influence the pecul-
iarities  and distribution of man, changing the  tint of his skin,
altering the shape of his skull and features, and influencing his
habits and mental qualities to such an extent  as to produce  a
number of races that differ so widely  in their characteristics as
to have given origin to the doctrine that all men have not been
produced from one original pair, but that there have been  a
number of different points of origination  corresponding to the
different races or types of men.
  The  two theories of the Unity and the Diversity of Origin
have numerous and influential supporters  among the highest in-
tellects, but the majority of savants accept the doctrine of the
unity of the race, which is by far the most natural and proba-
ble, explaining the differences that exist by demonstrating that
they are produced by the action of external physical agents.
   One  of the  most striking differences is the  variation in the
color of the skin, that of the inhabitants of tropical regions be-
ing  olive-colored or black, Avhile, as Ave pass northAvard, it be-
comes lighter, until finally, in the temperate regions, it is white,
or of a pale pink tint.   The best illustration  of the influence
of temperature on color is afforded by the Jews, A\ho, though
scattered among all the nations of the earth, have preserved
their national type intact by continuing  to intermarry  among
themselves; yet their color varies with the locality they inhab-
it, some being as Avhite  as the pure-blooded  Caucasian, while
others, who lived in tropical  climates for many centuries, are
black, but preserve the Jewish features unaltered.
   The  change in color of a race requires  many generations for
its accomplishment, but  there are other  characteristics  of the
different types Avhich  are  more profound in their nature, and
therefore necessitate the lapse of a  far longer period of time
to affect them; among these are the  peculiarities in the figure
of the skull, and variations in the size of the cranial cavity and
  What species of animals are most widely distributed ?  Is man subject to the influence of
physical agents ? What are the two theories regarding the origin of the human  race ?
Which is  most generally received? How does the theory of the unity explain the produc-
tion of races?  Give an illustration of change in color due to external physical agents.
What other characteristics of race exist besides color ? 
MEASUREMENT OF  SKULLS.               229
brain, which  determined, to  a certain extent, the intellectual
poAver.
  Skulls are  measured by two methods, one of which consists
in filling the  cranial cavity with shot or peas, and pouring the
contents into  a measuring glass, while the other is the determ-
ination of the facial angle.  This is performed by drawing two
lines, one from the  meatus auditorius externus to the base of
the nasal cavity, where it meets another drawn along the me-
dian  line from the forehead to the  same point;  the angle in-
cluded  between these two  straight  lines is called  the facial
angle.
  The variations in this angle are shown in the  adjoining fig-
ures  of skulls.   In the highest types it is  over 90°, Avhile in
the negro it falls sometimes as low as 70°, approaching to that
of the monkey, in which the  facial angle measures 50° in  some
of the higher  species.
Fig. 165.                           Fig. 166.
European.                         Negro.
Fig. 167.                          Fig. 16S.
Chimpanzee.                         Orang.
  How are skulls measured?  AVhat is the facial angle? How does it differ in measure-
ment in different races ? AAThat is the facial angle in the monkey ? 
230             DIVISIONS OF NATIONAL  LIFE.
  Though a very considerable period of time is required in or-
der to influence the configuration of the skull, we find that
when the highest race is  subjected for ages to debasing influ-
ences the type of the skull gradually changes, the chin becomes
more prognathous, the intellect is lower, and  all the energies
are spent in obtaining food and in the gratification of the ani-
mal propensities.
  As the life  of an individual is marked by periods of devel-
opment and decline, so also the lives  of nations or other collec-
tions of men show the same phenomena of gradual growth  in
power and intellectuality until they reach a maximum, which
is maintained for a certain period, after which a decline sets in,
and  sooner or  later the nation dies of old age.
  Professor J. W. Draper  has divided national  life into five pe-
riods, analogous to the five periods in the life of an individual.
They are the Age of Credulity, the  Age of Inquiry, the Age
of Faith, the Age of Reason, the Age of Decrepitude; and  in
his work on the Intellectual Development of Europe he has
demonstrated  the existence of these periods, and the influence
of physical agents on the course and duration of national life,
in the  most interesting and satisfactory manner.
 What conditions change the facial angle ?  What is the course of life of a nation ? What
are the five ages of the life of a nation ? Do they show the same subjection to physical
agents as individuals ? 
THIRD  DIVISION.
       HYGIENE.
                     LECTURE XLIII.
                             FOOD.
Divisions of Hygiene.— Conditions essential to a healthy State of the Di-
  gestive Apparatus.—Number of Meals per Diem, and the Times at which
  they should be taken.—Adaptation of Food to the Age of the Individual.
  — Varieties of Milk.—Food of Infants.—Influence of the Diet of tlie
  Mother on the Character of her Milk.—Selection of a Nurse.—Frongi-
  pane.—Butter.— Cheese.—Age at which solid Food should be given to a
  Child.

   Hygiene may be studied in regard to its applications to the
functions of, 1st. Digestion; 2d. Respiration; 3d. The skin; 4th.
Muscular, nervous, and osseous tissues;  and, 5th. Prophylactics
and quarantine.
   The first  and most  important  condition to be observed in
keeping the digestive organs in a healthy state is regularity in
all the acts  connected Avith them.  The  time at  Avhich the
meals are taken should be as nearly as possible  at the same
hour each day.  Three meals a day are sufficient for the  ordi-
nary Avants of adults; the first, called breakfast, should, as its
name signifies, be small in quantity, Avhile the chief meal of the
day should be taken in the  afternoon, to supply the materials
out of which the tissues of the body may be renovated during
the night.
   In his excellent work, Erasmus Wilson draAVS particular at-
tention to the influence of diet.   He maintains that  the proper
regulation of the meals is, breakfast at 8 or  9; lunch  at 1  or
2, Avith a cup of tea or coffee; and  dinner at 6 or 7.  This ar-
rangement alloAvs an interval of five hours between  each meal;
and, since the stomach requires on  an average three hours for
the digestion of an ordinary meal, it is alloAved tAvo  hours rest,
  AVhat are the divisions of hygiene? What is the  essential condition for perfect health of
the digestive apparatus?  How  many meals a day should adults take?  At what time
should the meals be taken ?  AAThat is the advantage of the arrangement suggested by Wil-
son ? 
232            ARRANGEMENT  OF THE MEALS.
which is necessary in order that it should perform its Avork in
a satisfactory manner.  The  habit of eating betAveen  meals is
most reprehensible, its certain result being a loss of natural ap-
petite, dyspepsia, and a numerous train of accompanying evils.
In regard to this habit Wilson says:  " The stomach is a patient
drudge, but tease it not, fret it not, if you would keep it in a
good humor, and Avithout its good humor, alas for yours." The
great  argument  in favor of seA^en o'clock as the dinner-hour is,
that nearly all men have finished their  daily occupations at
that time, and are ready  to dismiss  the " shop," together with
the cares and annoyances of business, and, donning their " de-
cent black," assume the human condition again, in Avhich they
can enjoy the pleasures of the table and fireside without the
fear of some  summons to business, which, by diverting the
blood from the  stomach to other organs, is apt to cause dys-
pepsia.
  The above  may be regarded as the most philosophical ar-
rangement of the meals, and the majority of men follow it more
or less closely, though the occupations of some, as physicians,
often  interfere with the rigorous adoption of any system.  In
the savage state there is  perhaps the greatest irregularity, for
the food is to be obtained by hunting, which is always uncer-
tain in  its fortune, and a savage is proverbially improvident,
consequently he may often pass days without procuring a suf-
ficient supply, and then gorge himself to repletion when oppor-
tunity offers.  The result of such a system is the reduction of
man to  the level of a mere animal, for savages, as they are just-
ly called, make the obtaining of food the chief object of their
lives.
  A proper adaptation of the food to the  age and occupation is
also of very great importance.  Articles which agree perfectly
with an adult are almost poisonous to an infant, while a con-
tinuous diet of milk would try the powers of an adult severely.
  During early  infancy the safest article of food is milk.  If
the natural supply is interfered with in  any way, the proper
substitute is cows' milk,  diluted with two or three times its
bulk  of water, sweetened with  sugar, and  administered luke-
warm.  After a while, pap, formed by  adding a little flour to
the milk, is the most suitable article of diet until the teeth com-
mence to appear.

  Should food be eaten between meals ?  What is the a'dvantage of a late dinner-hour ?
May all articles of food be used indiscriminately at all times ?  What is the best substitute
for human milk in the diet of infants ? How should it be prepared ? 
INFLUENCE OF  DIET ON THE MILK.
233
  The time that a  child should be allowed to  nurse at the
breast differs in different countries.   The  majority of Avomen
habitually nurse their children for two years, and even longer,
to avoid the rapid succession of births, since it is  exceptional
for a woman to be impregnated while she  is yet nursing; the
menstrual  Aoav also  does not generally reappear until the se-
cretion of  milk has been greatly reduced or entirely stopped.
The  proportions  of  butter, casein, and sugar in the milk of
Avoman,  compared with that of domestic animals, is shoAvn in
the folioAving table :
               Butter.           Casein.          Sugar.
              Sheep,          Goat,          Woman,
              Cow,          Sheep,         Ass,
              Goat,          Cow,          Mare,
              Woman,         Ass,          Cow,
              Ass,           Woman        Goat,
              Mare.          Mare.         Sheep.
  The character of the milk exerts an important influence on
the health of the  child, extraordinary articles of food, and med-
icines Avhich haATe been taken by the mother or nurse, changing
the  secretion of the mammary gland in such a  manner  as to
render  it highly  deleterious to the  child.   Familiar  illustra-
tions of this fact  are often furnished by, cows' milk, AAmen the
animal has fed on turnips, wild onions, or other vegetables that
possess a marked flavor.
  Special attention should be paid to the condition of the milk
of the nurse or mother Avhen children are sick, as  the malady is
often due to the changed state  of the secretion.   Advantage is
frequently taken of this channel in the administration  of medi-
cines to  children, and it is, as a rule, best to introduce the med-
icine into the system of the child by giving it to the nurse, and
so impregnating the  milk Avith the desired  properties.
^  The choice of a nurse is a matter Avhich  parents often disre-
gard or  pass OA'er lightly, yet  it is most important as regards
the future welfare of the child, for it is well knoAvn that certain
specific diseases may be in this  manner communicated to the
child, and  there is but little doubt that some hereditary dis-
eases, as consumption, may likewise be transmitted from the
nurse to the child.   Some Avriters even consider  that traits of
character, such as temper, may also be communicated  through,
this channel, but it is a statement to be received Avith consider-
  How long should a child be allowed to nurse at the breast ?  How does nursing influence
impregnation?  AVhat are the relative proportions of butter, casein, and sugar  in the milk
of woman and the domestic animals ?  Does the diet of the mother or animal influence the
character of the milk ?  How may medicines be administered to young infants ? AVhat dis-
eases may be communicated through the milk of the nurse ? 
234
PREPARATIONS OF  MILK.
able allowance; yet, as prevention is ahvays better than cure,
it is wise, in making a choice of a nurse, not only to take into
consideration her OAvn physical health, but also to pay some at-
tention to, any hereditary taint that may exist, and also to ex-
amine into her mental  peculiarities.  As illustrations  of the
prevalence  of these  opinions  even in remote times, we  may
quote the Roman fable  that the ferocity  of Romulus Avas due
to his having been suckled by a  she wolf, Avhile the amorous-
ness of Jupiter was  caused by his having been fed chiefly on
goats' milk.
  Milk, though well adapted  to  the wants  of children, often
disagrees Avith adults, producing severe dyspepsia.   When it is
desired to employ it  in spite of this objection, Ave may take ad-
A7antage of the tendency of the fluid to separate spontaneously
into three  constituents, auz., cream, card, whey, and by adminis-
tering the  cream and Avhey, avoid the disagreeable symptoms
Avhich are  nearly ahvays produced by the curd, which  coagu-
lates in the stomach, and either passes through the intestine
unchanged, or is ejected by vomiting.  It  is often the case that
when milk is boiled it will  agree perfectly; the addition of a
little salt produces the same result.
  An excellent preparation of milk, called frangipa?ie, is form-
ed by evaporating it to dryness, and adding pulverized al-
monds and  sugar; it is highly nutritious, and is given with ad-
vantage  to patients  suffering with phthisis  or  consumption.
Butter is of itself very digestible, but when melted it  under-
goes change, and is often highly indigestible.  Cheese is very
indigestible, and  this property is increased by  cooking, the
Welsh rarebit being  one of the most unmanageable and rebel-
lious substances that can be introduced into the stomach.  Some
varieties of cheese  prepared in Germany, and that made  in
Cheshire, in England, occasionally produce symptoms of pois-
oning.
  The appearance of the teeth indicates the necessity of modi-
fying the diet; more substantial articles may now be gradual-
ly added, such  as  well-cooked bread Avhich  is at least  a day
old, portions of beef  and other digestible meats, and a moder-
ate supply of fresh fruit.   The quantity taken at each meal by

  What points should be attended to in the choice of a wet-nurse? AAThen milk does not
agree with an adult, which constituents may be used with impunity, and how may thev be
obtained?  AVhat is the effect of boiling on  milk ?  AVhat is frangipane ? What is the ef-
fect of cooking on the digestibility of butter ?  What is its effect on cheese ? What varieties
of cheese are apt to produce symptoms of poisoning?  At what time should a child com-
mence to take solid food ? What substances should be selected ? 
        EFFECT OF DIET  ON THE RATE  OF MORTALITY.     235

a child should be small, and the meals  should be administered
more frequently than to  an adult, for the Avants of the system
at this period of life  are very urgent, and four moderate  meals
a day will give better health than three.
   In cities, the great mortality Avhich exists among children in
the  summer season  is chiefly  due to  the  careless manner in
which they are allowed to devour all kinds of unripe and half-
decayed fruit and vegetables.   Among the children of those in
affluent circumstances an immense amount of eATil is produced
by their absurd and criminal indulgence at the tables of their
parents in such articles  as pork, lobster salad, new potatoes,
stale fruits from the city stalls, cake,  and  pickles, being indi-
vidually capable of giving any child a diarrhoea, and yet we
often see them all administered at one meal by an indulgent
parent, when the child should be in the nursery partaking of
pap, Avith  a little meat  and bread, if it is desired to have  it
grow up into a healthy adult.
                     LECTURE  XLIV.

                       OF ANIMAL FOOD.

Conditions that produce Scurvy.—Prevention of Scurvy.—Extraordinary
  Articles employed as Food by the Ancients and Moderns.—Peculiarities
  of the Flesh of young Animals.—Effect of the Food on the Flesh of an
  Animcd.—Efect  of Season.—The Fumet.—Age at which the Ox and
  Sheep reach Perfection.—Effect of Castration on the Flesh of Animals.—
  Nutritive Properties of lean and fed Meat.—Proper Time and Method of
  Slaughtering.—Nutritive Qualities  of the Flesh of Birds.— Castration
  and Cramm ing of Birds.—Effect of Cooking on the Digestibility of Eggs.
  —Poisoning by unwholesome Flesh.—Fish and Reptiles used as Food.
  — Caviare.— The Oyster and other Shellfish.

  Though the teeth of man shoAV that he is omnivorous, there
are many tribes  that live in  northern regions that subsist en
tirely on animal food, all vegetable  supplies failing in extreme
northern climates.   In the torrid zone, on the contrary, animal
food is not employed, and it is only in the temperate parts of
the earth  that  man  can be  strictly said  to be  omnivorous.
When the  system has once  been accustomed to the  use of a
mixed diet of both animal and  vegetable  substances, a total
abstinence from  either is very apt to produce a diseased  condi
  How many meals a day should be given to a child ?  AA7hat is the chief cause of the mor-
tality among children during the summer season?  In what region  is man truly omnivo-
rous ? 
236       EXTRAORDINARY ARTICLES USED AS  FOOD.
tion of the system, to which the name of scurvy is given.  It is a
very common error to suppose that scurvy is ahvays due to the
continued absence of vegetable food, but the long-continued ab-
stinence from animal food will produce the same result. _ The
vast majority of cases, however, occur on ships and in armies in
which there is  a  want of a sufficient supply  of vegetable sub-
stances.  The proper method for avoiding  the  disease is to
furnish the missing ingredient, or to allow a  regular ration of
lemons or some vegetable acid, such as vinegar.  The modern
system of preserving Aregetables by hermetically sealing them
has obviated all necessity for the existence of this disease, and
it Avill doubtless, in future, be almost unknoAvn in navies, Avhen
it is so much  to the interest of governments to preserve the
health and efficiency of their sailors.
  All parts of  animals, excepting some of the secretions, are or
have been employed as food.  Among the ancient Romans, the
brains of the ostrich and peacock, and tongues of nightingales
and other singing-birds, were much sought  after.  The vulva
of the sow Avas also highly valued as a dish; and the gravid
uterus and  foetal pigs of one of these animals  that had 1 >een
trampled to death  was considered Avorthy of the table of an
emperor.  They  were also very fond of the flesh of the young
ass; and young fat puppies were a  great dainty in Corsica, and
continue to be held  in high repute among  the  Chinese.   At
the present time the Tartars esteem the after-birth or placenta
as  a great  delicacy,  and the  civilized disciple of Epicurus in
our own country regards the trail of the woodcock as the bonne
bouche of his most luxurious dinner.
  'Among the  extraordinary substances employed as food we
may cite the instance of the quarrymen of Thuringia, who  eat
a substance called rock-butter, Avhich they spread on their bread.
A  species of clay is  an article of diet among the Ottomaques
of  South America, and Humboldt states that they  devour
enormous quantities, so that their stomachs are greatly distend-
ed; he also thinks that they derive some nutriment from it.
This is not at  all improbable, for the clay that is eaten by the
troglodites  of  South Carolina is found to be composed, to  a
considerable extent, of animalcules.  The amount of nutriment
that may exist in substances which are apparently devoid of
it is well shown by the growth of gold-fish, Avhich are kept for

  What are the  conditions that produce scurvy ? How may scurvy be prevented ? Mention
some of the articles regarded as luxuries by the Romans.  Mention some of the extraordi-
nary substances at present employed. 
          EFFECTS OF FOOD  AND SEASON ON  MEATS.       237

years in a small globe of water, and, though they are never fed,
obtain sufficient food from the animalcules in the water, and
animal  and ATegetable ova falling into it from the  circumambi-
ent air, to reach a very considerable size.
  The flesh of young animals contains  a greater proportion of
gelatin  than that  of the adult; it is therefore softer and more
soluble in water, though not more digestible, as is shown in the
instances of veal  and lamb, both of which are less digestible
than beef and mutton.
  The effect of food on the flesh of animals is shown by the
rank character of that of the carniArora.  The nations that eat
the flesh of such animals generally cause them to  subsist on a
vegetable diet, so as  to render their flesh edible.   The great
superiority of the  Virginia hams over those made from still-fed
hogs is in great measure due to the fact  that the former are
allowed to roam through the forest, and subsist on acorns, chest-
nuts, and roots, and are  finally fattened on  corn, and not  on
SAvill or household garbage.
  Many animals  are unfit for use as food at certain  seasons.
Pork, for example, is not used during the summer, and the  flesh
of the buck is valueless in the rutting period.  The flesh  of
most  animals reaches perfection in  the early part of the  Avin-
ter, at Avhich time our tables are so freely supplied with game,
Avhich is then  in  season.  The flesh of the females that have
been  recently  delivered is not fit for use, being tasteless and
insipid, and not regaining its flavor until some time after the
lapse of the suckling period.
  The digestibility of all meats is improved  by keeping them
until they commence to give evidence  of incipient decomposi-
tion.  Meats are generally cooked too  soon after the animal is
killed, and with us  venison  and game  are  the only articles of
food that are alloAved to gain their true flavor.   In Great  Brit-
ain mutton  is always hung until its flavor is pronounced; and
the game served at the table of an  epicure  usually gives un-
equhrocal evidence of having been kept for some time, since it
requires educated olfactory  nerves  to  Avithstand the perfume
eA^olved, to which  the euphonious designation of the fumet has
been given.  It is said that the Siamese  carry this system to
the greatest perfection, and consider the decayed egg that con-
tains a chick the special delicacy with which to tempt a guest.
  AVhat is the peculiarity of the flesh of young animals ?  Is the flesh of young animals as
digestible as that of those that are full grown ?  Does the food of an animal have any effect
on its flesh ?  How does the season influence the flesh of animals ?  What is the effect of
keeping meat on its digestibility? AVhat is the fumet? 
238    AGE AT WHICH CATTLE SHOULD BE SLAUGHTERED.

  In the United States there is not sufficient attention paid to
the age of the slaughtered animals, our  butchers killing their
stock when it is demanded, or when they can  obtain it, with-
out any reference to its size, condition, or age.  In the London
markets the ox is regarded as reaching perfection at about the
seventh year, and the  Avether-mutton of England, which has
earned a world-wide reputation, is not killed  till the fifth year.
The  effect of castration on the texture and flaA^or of meats is
very singular, that of the  neutral or castrated animal being far
superior  to that of either the  entire male or female; the fat
also is more  evenly distributed, and the meat has a higher nu-
tritious power, since it is said that one ounce of fat meat will
furnish an amount  of nutriment  equal to that obtained from
four ounces of lean meat.
  Before being  slaughtered, animals should  be kept without
food; for, if the gastric juice is being secreted rapidly  at the
time of death, it is  apt to perforate the  stomach, and induce
changes in the flavor of the flesh.  These effects are more fre-
quently found in fowls than any other article offered for sale in
our markets, the object being to increase the weight of the bird.
All poultry with a distended crop or craw should therefore be
avoided, for the flesh is very apt to possess a disagreeable flavor.
  It was  the custom at  one time to bleed animals «to death
slowly, and killing animals by the chase  is still thought to im-
prove the quality of game.  In some of the receipts in the cook-
ery books of past times we find such  directions as the  follow-
ing:  "To mctke a pig taste like a wild boar.—Boil together in
vinegar .and  water  some  rosemary, thyme, sweet  basil, bay
leaves, and sage; then take a living pig, make him swallow the
above drink, and whip him to death, and roast  him immediate-
ly."  It is supposed by many  that the vinegar in the preced-
ing preparation softened the muscular tissues, and rendered it
more digestible.  It is said that the proper way to kill a hedge-
hog is for two men to take him by the legs,  and rub his back
backAvard and fonvard over some hard substance like a stone
until it ceases to squeal, and then cut his throat.
  The method of slaughtering now adopted  in civilized coun-
tries is either to  cut the throat, or, in  the  large animals, to

 At what year does the ox reach  perfection? At what  age should mutton be killed?
What is the effect of castration on  the flesh of animals?  What is the relative nutritive
power of lean and fat meat ?  What is the objection to slaughtering animals immediately
after eating?  What is thought to be the effect of administering  vinegar to an animal
about to be slaughtered ?  What is the method of slaughtering adopted in  civilized coun-
tries ? 
EFFECT OF  CASTRATION ON FLESH.
239
knock them on the head, and then cut their throats as quickly
as possible, that the blood may Aoav out of the body.   In the
French abattoirs they then beat the slaughtered animal with
staves, and inject air into the cellular tissue by means of a suit-
able forcing apparatus, Avhich operation greatly improves the
appearance of the meat.
  The flesh of birds Avhose meat is dark is much more nutri-
tious than that of the white-fleshed birds; and Stark states that
in the  series of experiments he undertook on diet, he found that
he Avas more vigorous when  he ate roast goose than any other
article, but  that may have  been in part  due to the brandy
Avhich he probably took as a " peptic persuader," as it has been
quaintly termed.
  Castration has the same effect on birds  as on animals, ren-
dering their flesh more palatable and delicate, a crammed cctpon
or poulard being one  of the most highly-esteemed of modern
dishes.  It is said that the Romans blinded the fowls that
Avere to be crammed, to insure their being in the dark.  The
method of cramming at present employed  is to  keep the foAvl
in a dark Avarm place, and force doAvn their throats every hour
a paste made of barley meal, molasses, suet, and  milk.  In  a
couple of Aveeks the operation is finished, but if continued lon-
ger the creature is liable to  an attack of fever, and is then un-
fit for use.
  The digestibility of  eggs  depends on the manner in which
they are cooked, frying being the worst method, as is shown by
the table page  59.  The French writers on cookery mention
more than 600 preparations  of eggs, but of these the most di-
gestible is that in which they are boiled  soft, in which state
they are slightly laxative, Avhile by all the  other methods they
are rendered more or less constipating.
  The flesh of animals that have  died  from natural causes is
universally knoAvn to be unhealthy, and numerous instances of
death  from the use of such food are  recorded.   As an illustra-
tion, Ave furnish a case from the London Medical Repository,
AAdiich states that in 1826 a family on the Galloway coast ate a
stew made of the meat of a dead calf.   They all suffered with
violent pain, purging, vomiting, and, when aroused from the
stupor into which they quickly fell, the countenance assumed a
wild expression;  one  died  in  about six hours, but the rest
 AVhat class of birds furnish the most nutritious flesh ?  What is the effect of castration on
the flesh of birds ? AVhat is meant by cramming, and how is it conducted?  How does the
method of cooking influence the digestibility of eggs ? Is the flesh of animals that have died
from disease fit for use ? AVhat are the symptoms produced by eating unwholesome flesh ?
• 
240         USE OF REPTILES AND FISH AS FOOD.

eventually recovered.  The steAV  had a nauseous smell and a
black color.   In his work on Poisons, Dr. Christison cites a
case  of a family that partook of broth made from beef which
had a black color, and Avhich caused symptoms similar to those
described above, and which he thinks were due to the unsound
state of the meat.
  The articles which are more  apt than any others to produce
the symptoms related above are  the sausages made of liver,
meat, and blood, and which are very generally used by Ger-
mans.  The poison they contain  is very dangerous, and it is
said that in the Wurteniberg territories 234 cases of poisoning
from  this  cause Avere recorded betAveen  1793  and 1827,  of
Avhich 110 were fatal.
  Bacon, and all cured meats,  together Avith cheese and milk,
have  from time to time  furnished undoubted cases of poison-
ing when they have undergone change.
  Salted meats are more indigestible than  those  which are
fresh, and when dried and salted they are  only dissolved  with
great difficulty hy the gastric juice.
  The class of reptiles furnishes but few representatives to the
table, but these are highly prized; we need only mention the
turtle  and frog, and all epicures will at once acquiesce in the
statement.   In addition to these, the eggs of many reptiles are
also  used, and  some of the Asiatics eat the flesh of certain va-
rieties of lizards.
  Fish forms the principal article of diet of many nations, but
they are generally a poor and miserable class of people, devoid
of all ambition, and steeped in  poverty  and ignorance.   St.
Jerome gravely relates the story that when the executioner at-
tempted, by  the order  of Nero, to bleed Seneca to death, he
could not find any blood in his veins, because he had lived on
fish and fruit.
  It is a very common idea that  a fish diet renders a popula-
tion very prolific, and the great proportion of children found in
China gives  support to the  opinion.   It has also been stated
that a fish diet is liable to produce leprosy; at all events, it is
a well-known fact  that a continuous diet of fish is conducive to
the production of nearly all skin  diseases, and there are many
persons who suffer severely with herpes, and other painful skin
diseases, if they eat the smallest portion of fish, and especially
  What sausages produce similar symptoms ? What other articles of food cause poisoning ?
Are salted meats as digestible as those that are fresh ? What reptiles are used as food ?
 What is the effect of a long-continued fish diet?  What variety offish is most apt to pro-
duce herpes?
1 
USE OF  SHELL-FISH  AS FOOD.
241
of shell-fish.   All fish that have commenced to assume the pu-
trefactive state are unsuitable for use as food, and should never
be  eaten.  We may also say that all fish lose by being kept,
and if it is desired to serve them in full perfection, they should
be cooked Avhile yet animate.
  Among the substances that are highly prized by epicures is
a preparation of the  roe of the  sterlet or sturgeon, which is
knoAvn  as caviare.  The best  is  obtained from Russia; that
derived from the American  sturgeon is very indigestible, and
produces severe gastric disturbance.   At the head of the list
of edible  fishes Ave place the trout  and salmon, which are uni-
versally esteemed, and yet it is said that e\^en these may be im-
proved  by castration.
  Of shell-fish the oyster is the  most digestible, especially when
eaten raw, and Avith the addition of a little Cayenne; they are
Avell adapted in this form to invalids avIio are just commencing
to convalesce.  Those that are transplanted are edible at all
seasons, and possess  a good flavor during the  spaAvning sea-
son, -/. e., May, June, and July, when the native oysters are not
edible.   Oysters are generally thought to possess an  aphrodis-
iac power, but the statement is not founded on facts.
  In  Switzerland the  snail is much esteemed, and gardens arc
devoted to their cultivation.   Crabs and lobsters are held  in
high  repute in all cities on the  sea-shore, and the  clam  and
mussel also have their admirers, but the latter are more liable
than any other fish to produce  symptoms of poisoning.
  The effects of the  Aarious  methods of cooking ha\Te  been
shoAvn in the table (page 59), in Avhich it is demonstrated that
the method by broiling is the best.  In boiling, a considerable
portion of the nutritive material is  removed by the soh^ent ac-
tion of the water, so that Ave can  prepare in this Avay extracts
of greater or less strength, Avhich are generally knoAvn as soups.
If the meat is placed in the Avater Avhen it is cold, and the tem-
perature of the liquid gradually elevated, the loss of nutritive
material will be far greater than Avhen  the flesh is dropped into
boiling  water.  In roasting, the crust that forms on the  exte-
rior of the joint prevents the escape of the nutritive  portions;
and though  the mass may lose  more Aveight than  if it  Avas
boiled, owing to the evaporation of water and melting of fat,
it possesses greater nutritive poAver.  It is said that  beef loses
 Is stale fish fit for use? What is caviare ? AAThat is the effect of castration on the flesh
of fishes ?  Under what form is the oyster most digestible ? How may it be rendered edible
at all seasons? AVhat other shell-fish are used as food ?  AVhat is the best method»of cook-
ing? How should soups be prepared?
                             Q 
242
WHEAT  AND  RYE  FLOUR.
by boiling one fourth of its original  weight, and mutton  one
fifth, whereas they both lose about one third by roasting.
                      LECTURE  XLV.
                 OF  VEGETABLE  FOOD.
 Vegetable Food less wholesome than Animal Food.—Bread best adapted
  to Dyspeptics.—Indigestible Character of Pastry.—Rusted or Ergot Rye.
  — Prejudices against the Use of Oatmeal. — Use  of Cornmeal. — Pella-
  gra.—Polenta.— Use of Legumens.—Indigestibility of Nuts.—Effect of
  Cooking on Digestibility of Potatoes.— Use of raw and cooked Cabbage.
  —Salads.—Sugar does not injure the Teeth.— Concentrated Solutions of
  Sugar most Digestible.— Classification  of Condiments, and Effect of in-
  sufficient Supply of Salt.—Anchovy and Bloater Pastes.— Use and Abuse
  of Vinegar.—The aromatic Condiments.—Effect of Climate on the Na-
  ture of Diet.—Effect of Occupation on Diet.—Idiosyncrasies.—Effect of
  Irregularity in the Evacuation of Fceces.
  Far  greater  care is  requisite  in the selection of vegetable
than of animal  food, for there are  many plants which possess
an injurious action on  the human system, and many of those
Avhich are in ordinary use frequently become so changed in their
character as to  cause violent disturbance to the  digestive ap-
paratus, which is sometimes so severe as to result in  death.
  The chief article of food of a  vegetable origin  is bread, and
we have (in Lecture XI.) mentioned some of the varieties em-
ployed  and the  mode  of preparation.  When bread made from
the finest wheaten flour produces dyspepsia, it will be general-
ly found that the  flour which  contains a portion of the bran
will furnish bread that Avill be  digested with  ease, the  bran
acting as a gentle  stimulant to the  stomach and intestines.
  The preparations of wheaten flour  known as vermicelli and
macaroni are very nutritious and easily assimilated; but all ar-
ticles of pastry are unwholesome, and cause dyspepsia  more
frequently than any other substances.   The lighter varieties of
puddings are wholesome, but those made with fat or suet are
very indigestible, as the fats are not acted on in the stomach,
and, by covering the  particles of flour, protect them from the
action of the gastric juice.
  Rye is also extensively used in the preparation  of bread, and
  What is the relative loss of weight of beef and mutton by roasting and boiling?  Are veg-
etables as uniformly wholesome as animal food? What variety of bread is best adapted for
use by dyspeptics ? Is pastry digestible ? Why are articles prepared with fat or suet indi-
gestible ? 
             RICE, INDIAN CORN, AND LEGUMENS.          243

is an excellent article of diet.  It is, however, liable to  a dis
ease called the rust, Avhich also passes under the designation of
spurred rye, or ergot; such grain produces violent contractions
of the uterus, and when used for any length of time as an ordi-
nary article of diet, causes dry mortification of the extremities.
  Though it is highly nutritious, there is a common prejudice
against the use of oatmeal, many people thinking that it is apt
to produce cutaneous affections, and that it  is one cause  of the
existence of such diseases in Scotland; but the same diet  is
employed in the north of England, and skin diseases do not ex-
ist there to any very great extent, showing that there must be
some other cause than an oatmeal diet for their prevailing so
extensively in Scotland.
  Rice flour and  potatoes are often added to wheat flour in the
preparation of bread; there is no objection to their use, and in
skillful hands they are a decided improvement.  Indian corn is
in common use in this  country, and in  the Southern States has
ahvays been the chief article of diet for the slaA^es.  It  is not
well adapted to the constitutions of those who are liable to in-
testinal disturbances, and who are not accustomed to it.  Many
will be surprised to learn that in Lombardy a  loathsome dis-
ease, called pellagra, has appeared during the  last  century,
which has been attributed to the introduction of Indian corn
as an article of diet, the Italians being  very  fond of a dish call
ed polenta, Avhich is composed of cornmeal and cheese. ,
  The legumens, as. peas and beans, are highly nutritious, and
form, Avhen dried and thoroughly cooked, an excellent  article
of diet for those  Avho are obliged to work hard.  Some varie-
ties  are eaten Avith the pod when they are very young and ten-
der, but they are very indigestible unless  they are well boiled.
The nuts that are introduced at many tables are all more or
less  unwholesome, since they eontain oils which are  not acted
on in the stomach, and consequently the digestion of the  farina-
ceous parts is thrown on the lower intestine, and is imperfectly
performed.
  Of the roots, the beet, carrot, parsnip, turnip, etc., all contain
sugar, and are slightly nutritive when young.  They  should be
well dried before they are eaten.  The radish, onion, leek, and
such articles,  are  all indigestible, and should be employed in
small quantity as condiments rather than as articles of food.
  Under what circumstances is rye unfit for use ? What prejudice exists against the use of
oatmeal ?  Is there any objection to the addition of rice flour or potatoes to bread ? Under
what circumstances does cornmeal disagree ? What is pellagra ? What is polenta ?  AVhat
are legumens ?   Are they adapted to all constitutions ?  Why are nuts indigestible? 
244
VEGETABLES EMPLOYED AS FOOD.
  Of the varieties of potato, those which are mealy are the
most digestible, but it depends to a great extent on the man-
ner in Avhich they are cooked.  If they are sodden in salt Ava-
ter, the best potatoes will be injured; the proper methods to
be employed in preparing them is either by steaming or roast-
ing until they almost fall to pieces.  The potato is at times
liable to be destroyed by a disease which commences in the in-
terior, and which is commonly knoAvn as " the rot." ^  It has oc-
casionally produced great suffering among such nations as .the
Irish, who make it the chief article of food.  The sweet or Car-
olina potato is'very nutritious, but is not so easy of digestion
as the Irish or common potato.
  The vegetables of  which the  cabbage, asparagus, spinach,
and cauliflower are examples, often disagree  with those AArho
are not dyspeptics, and the great majority of people find that
cabbage is much more digestible when eaten raw than when it
is cooked.  Lettuce, celery, and  the  like  salad herbs are al-
most  invariably employed in the uncooked  state,  and  often
agree with  a  dyspeptic when mingled with oil, mustard, vine-
gar, and condiments, while in the undressed state they would
cause a severe attack of indigestion.
  Mushrooms, cucumbers, and tomatoes are all held in high es-
teem as delicacies, yet they belong to classes of which some of
the members  are very poisonous.  This is especially the case
Avith the mushroom and cucumber.
  The fruits  are all Avholesome in their proper season, when
they are fully ripe, and have not  been kept for too great a pe-
riod of time.   Some, as the A^arieties of melon, produce diar-
rhoea in certain people, and are often suspected as being the
cause of visitations of cholera.   The evil consequences which
arise  from the use  of these and other fruits may be to a great
extent avoided by carefully rejecting  the skins, core, and seeds,
and using the pulp only.
  All fruits contain sugar, which is A^ery commonly supposed
to injure the teeth, but  this is  a mere prejudice, which has
probably arisen on account of economic reasons, for it has no
true foundation in fact, since the  negroes of the South in  the
sugar season partake of the juice  of the sugar-cane very freely,
 What varieties of potato are most digestible ? How does cooking affect the digestibility
of potatoes?  AVhat is potato rot?  Is the Carolina potato as digestible as the common po-
tato ?  ,In what form is cabbage most digestible ?  Under what form are the salad herbs
most digestible?  How may the evil consequences of eating fruit be in a great measure
avoided ? Why are we justified in supposing that the free use of sugar does not injure the
teeth ? 
SUGAR AND  CONDIMENTS.
245
and grow fat on it, yet their teeth are not injured, but are uni-
versally knoAvn and  admired for their beauty of form  and
whiteness.  It is estimated that in France the annual consump-
tion is 5 lbs. per capita;  in the United States, 10 lbs.; and in
England, 14 lbs.  Concentrated solutions of sugar often digest
readily, wThen a dilute sirup, in Avhich the  amount of water is
very great, is highly indigestible.  It is OAving to  this cause
that tea and coffee so  often disagree.
   Condiments are substances  employed to assist  digestion;
they generally contain either a bitter aromatic or an oily acrid
principle.  Another class, of which salt is an example, are pure-
ly saline, and Ave may justly regard it as the most important of
all the condiments, since  it is absolutely necessary to the prop-
er performance of digestion; and when it is not used in proper
quantity both by men and animals, we find that there is a dis-
position to the formation  of parasites in the digestive canal; for
in those countries in Avhich the criminals are forced to subsist
on a diet from which  salt is excluded, the unfortunates are lit-
erally destroyed by the worms that are produced in  the digest-
ive canal.   In ancient times, salt  was the first thing placed on
the table  and the last remoATed;  and it  is still the  custom
among  the Dutch families, when they change  their residence,
to take to their neAV abode first of all things a  Bible, for God's
blessing; a bag of salt, as the emblem of hospitality; a loaf of
bread, as the symbol of plenty; and a broom, to typify cleanli-
ness.
   The anchovy, bloater, and other paste-like condiments, which
are prepared from salted  fish, are very indigestible, and should
only be employed in small quantity.
   Vinegar alone, and  in  the form of pickles, is  a useful condi-
ment, and we haAre already alluded to the property it possesses
of assisting the gastric juice.   There  is a  common  idea that
when freely used it reduces embonpoint, and aids in producing
a slender, spider-like waist.  Whatever  effect it may have on
the figure is of very small importance compared with the fact
that, when  used in such  excess, it is utterly destructive of the
digestive powders, and, by the indigestion produced, causes not
only the waist, but all the other tissues to shrivel up, and re-
duces the sufferer to mere skin and bone.  The action of lemons,
and other acid fruits and juices, is similar to that of vinegar.
 Are concentrated or dilute solutions of sugar most digestible? Why do tea and coffee
so often disagree ? To what classes of substances do condiments belong ? To what class of
condiments does salt belong ? AVhat is the effect of an inadequate supply of salt ? Are the
anchovy and such pastes digestible ?  What is the effect of the abuse of vinegar ? 
246    EFFECT OF CLIMATE AND OCCUPATION ON  DIET.

  The aromatic condiments or spices, as ginger, cloves, nutmeg,
cinnamon, pepper, mustard, horseradish, onions, etc., are exten-
sively employed in all parts of the globe, since they assist the
deficient digestive powers of those whose stomachs are torpid,
and aid in the digestion of articles of food which would other-
wise cause  indigestion.   They act by  stimulating the  glands
of the mouth and stomach, and causing them to secrete their
fluids with greater rapidity.
  Variation in  climate should be met by variation in the na-
ture of the food.  An Englishman  may drink Avith impunity
beer and alcoholic fluids in his native land, but if he continues
the habit under the hot sun  of India his liver is quickly  dis-
eased, and his life shortened or forfeited.  The inhabitants of
hot climates require but little respiratory food; they are conse-
quently freely supplied by Nature  Avith a  great  variety of
sweet fruits, the sugar of which furnishes all the combustible
material they need, but in cold climates a  large quantity of
calorifacient food is  required to sustain the animal  tempera-
ture.  The inhabitants of such regions therefore resort to  the
use of fats and oils, without which they could not exist.
  Occupation also exercises a great influence on digestion.   A
soldier Avill consume his allowance of fat pork and beans every
day while he lives in the open air and has to undergo a severe
drill.  A laborer will also enjoy the same food Avith appetite;
but  if a  student or  person of sedentary habits partakes of it
many times in succession, he will  suffer severely from indiges-
tion so long as he continues  his inactive life; but when he
leaves his desk, and, taking his rod  or  rifle, lives in the open
air, he will  enjoy a daily  allowance of gross oleaginous food
with as much relish as a soldier.
  After paying proper attention to the  influence of the method
of cooking and the occupation of the individual on the  digest-
ibility of food, there still remain certain personal peculiarities
or idiosyncrasies, as  they are called, which  each person must
notice and study for himself.   Some Avill suffer  torture from
eruptions on the skin if they eat eA^er  so small  a portion of
shell-fish.   The odor of a rose or of neAv hay will produce asth-
ma in another, while they afford  pleasure to the majority of
people.  When, therefore, an individual finds that any article
of diet produces trouble in his digestive  system, he must exert
his  own good sense in the matter and aA7oid it.
  How do the aromatic condiments act ?  Does variation in climate affect the power, of di-
gesting food ? What is the effect of occupation on the digestive function ?  AVhat is meant
by idiosyncrasies? 
EFFECTS OF HABIT.
247
   Not only should regularity be observed in taking the meals,
but the evacuation of the fasces from the intestines should take
place every day at the same hour.   By attending to this duty
Avith regularity, a person will enjoy far better health, and avoid
those disagreeable and  annoying headaches AAdiich are certain
to arise when constipation exists.  Medicines may be used to
afford relief for a time, but it is the tendency of most purgative
drugs to produce  a  constipating effect after the  purgative ac-
tion;  they should  be therefore avoided, and the habit of evac-
uating the intestine at a certain hour established, when trouble
will very rarely arise.
   Habitus the most powerful of all agents in its effect, not only
on the digestive, but  also on the other systems of the body.  It
should therefore be cultivated to  as great an extent as possible,
for the body  quickly accommodates itself to any given duty,
and accomplishes a  definite  amount of work with far greater
ease when it is accustomed to it.
                      LECTURE XLVI.

                 FLUIDS  USED  AS  DRINK.

 Causes that produce Thirst.— Temperature at ichich Water should be em-
  ployed as Drink.— Use of Ice.—Natural Waters.—Differences between
  Rain and Spring Water.—Effects of Lime-water on the System.—Effect
  of Salines on rapidity of Absorption of Water. — Goitre. — Materials
  suitable for making Water-pipes and Tanks.—Protection of Lead Pipes.
  —Precautions to be employed in the Use of Lead Pipes.—Purification
  of Water by Filtration and Distillation.— Objections to the Use of sweet
  Drinks.—Toast-water.— Gruel.—Properties of Tea and Coffee.—Intro-
  duction of Tea.— Classification and Composition of Tea.—Effects of the
  Abuse of Tea.—Introduction of Coffee.—Preparation for Use.— Choco-
  late.—Soda-water.

  As hunger is the evidence of the demand of the  system for
solid aliment, so thirst shows the desire of the body for fluid
Avherewith to dilute its circulating juice, and furnish the liquid
required for the urine and perspiration.   The experiments of
Dupuytren demonstrate that the sensation of thirst may be al-
layed by injecting water into the blood-vessels; it Avould there-
fore seem to be dependent on the amount of water contained in
the circulating juice.
  Water is the natural drink of men and  animals, and the ma-
  What is the effect of regularity in evacuating the faeces ?  Upon what condition of the
system does thirst depend ? 
248
VARIETIES OF WATER.
jority of nations use  it at the temperature it possesses Avhen
issuing from the  earth.   Some valetudinarians insist that it
should always be taken at a temperature of 90° or 100°.  But
it appears far more natural to employ it at lower degrees, such
as 40° to 60°, Avhich is the ordinary temperature of spring or
well water.   The  use  of ice-water is objected to by many; but
when we reflect that its temperature can not be lower than 32°,
and that of natural water is from 40° to 60°, the objection ap-
pears to be  trivial, and not worthy  of consideration.
  Rain is the purest form of water  furnished by Nature.  The
first portions which fall in any storm wash the air, and remove
the floating dust and  noxious gases Avhich  it contains; this is
admirably adapted to  the wants of plants, but not so Avell suit-
ed to animals, though it is purer than the water usually em-
ployed.  The rain which falls during the latter part of a long-
continued storm is absolutely pure, and may be  used for the
same purposes  as distilled water.
  Spring and Avell Avater ahvays contain a  certain  proportion
of solid inorganic materials, derived  from the strata through
which the fluid has percolated.  In lime districts  the quantity
of carbonate of lime in the Avater  is very large, and produces
diarrhoea Avhen used by persons unaccustomed to it.   The evil
results  of the use of  such Avaters may  be  in part avoided by
boiling them, which expels the carbonic 'acid gas in the liquid,
and causes the lime to be precipitated.
  It  often happens, especially in large  cities, that  in passing
through the soil the water dissolves enormous quantities of or-
ganic matter from some sewer or other receptacle of filth.  Such
Avater is often remarkably pellucid and pure in appearance, but
in its action on the system  it is  most  deadly, producing the
worst forms of dysentery and low fevers.  The impurities may
be detected by an ordinary chemical analysis.
  Water, of all liquids, allays thirst with the greatest rapidity,
and is  absorbed with the greatest ease by the  veins of the
stomach.  The presence of a very small proportion of saline
material in  water reduces the rate of absorption, an individual
being able to drink a far larger amount of rain  or distilled Ava-
ter than of that obtained from a spring or Avell.   When dis-
  At what temperature is water generally employed ?  Is there any objection to the moder-
ate use of ice?  What is  the purest form of natural water?  Are the first portions of rain
that fall as well suited to the wants of animals as of plants?  What is the difference between
spring or well water and rain-water ? What is the effect of lime-water  on the system ?
How may the lime be removed? What are the peculiarities of water containing organic
matter ? How does the presence of saline matter in water influence its rate of absorption bv
the veins of the stomach ? 
 MATERIALS USED IN THE CONSTRUCTION OF AVATERWESSELS.  249

tilled water has been taken in these large quantities, it passes
off almost immediately by the  kidneys, the urine gradually
containing less and less solid material.   It has been humorous-
ly proposed that in diseases Ave  should, by drinking enormous
([uantities of distilled water, wash  out the system just  as we
cleanse a soiled garment.
   It was formerly supposed that the water obtained from melt-
ed ice or snoAv produced  the disease known as goitre, which is
a  swelling of the glands of the throat; but as it exists also at
the base of mountains on which snow never falls, it is evident
that it is due to some  other cause.  The  elephantiasis, AAmich
prevails in Egypt, was also supposed to be produced by the
use of the waters of the Nile; but it is almost impossible to fix
on water as  the  true cause of these and other diseases which
are endemic  in their nature, since they may also be  produced
by peculiarities in the air or vegetable growths of such regions.
   When the water from  lakes and  rivers is placed on ships, it
undergoes fermentation  in the tanks, and deposits a  large
amount of sediment.  After this purification, though it may re-
tain the odor and flavor of some of the products of the action,
it is much more wholesome and less liable to produce diarrhoea
and other intestinal troubles.
   The best materials that can he employed in the manufacture
of the tubes for conveying and tanks for holding water are
glass, Avood, and  iron, since they do not impart any poisonous
qualities  to it.   Lead and copper are used, but there are  great
objections to them, since if water is alloAved to remain in ves-
sels  made of these  metals it soon  acts on them, and becomes
more or less impregnated with metallic salts, which, render it
highly deleterious.  In the case of lead, which is so  generally
used in cities, the purer the water,  the more liable is it to act
on the metal;  but when it contains sulphates in solution, the
sulphuric acid, having a great affinity for the lead, unites with
its oxide, and forms on the  interior of the pipe  a thin insoluble
coating of sulphate of lead, which  protects the pipe from far-
ther action;  consequently, the water  drawn from old pipes is
usually free  from lead, A\Thile that taken from  a  pipe that has
just been laid is generally more or less contaminated.   Even in
the case of old pipes it is best to reject the first portions of wa-
  What is goitre, and what was supposed to be its cause ?  What change occurs in the river-
water placed in the tanks of ships?  What are the best materials that  can be employed in
the manufacture of water-pipes and tanks ? AVhat variety of water acts with the greatest en-
ergy on lead pipes ?  How do waters containing saline matter protect the lead from corro-
sion ?  AAThat precautions should be taken in using water from lead pipes ? 
250
PURIFICATION OF  AVATER.
ter that are drawn in the morning, and which have rested in
the pipes during the night, since they frequently contain an ap-
preciable amount of lead, even though the pipe is coated in the
interior with a layer of sulphate.
   Many of the impurities contained in water may be separated
by filtration.   On the great  scale, this may be done  by passing
it through many alternate layers of charcoal and sand, which
should be from time to time renewed.  In Paris there is an
establishment  at the Quai  des Celestins, where an immense
amount of water is purified by first passing it through sponges,
then through filters such as  those described above, and finally
causing it to fall through air in a fine rain, to allow it to absorb
the gases it has lost during the purification.
   On  steamers, a liberal supply of water can be obtained by
the condensation of steam.   The only objection to distilled wa-
ter is its  insipid taste; but  this can easily be avoided by agi-
tating it  Avith  air, or allowing  it to fall through a column of
air, as in the Parisian establishment spoken of in the preceding
paragraph.
   The infusions of various  animal and vegetable substances
are extensively employed by all nations as drinks; some of
these, as lemonade, are acid,  while others are sweet, as the eau
sucree, and the various sirups prepared with fruits  and  sugar.
Though such fluids are often gratifying to the palate, they are,
as a rule, injurious, and produce indigestion, attended by heart-
burn and flatulence.
   Toast-water, made by immersing well-toasted  bread in cold
Avater, is to many a very grateful drink, and rarely does harm.
It often relieves the breath of the disagreeable odor that it pos-
sesses in some people.
   Gruel made from coarse oatmeal is an excellent article either
for breakfast or supper when the powers of the stomach have
been enfeebled by indulgence.  It is also extensively employed
in the diet of parturient women, being very nutritious  and
tending to relieve the constipation which usually attends the
period of gestation.
   Tea and coffee form prominent constituents in the daily diet
of the majority of the inhabitants of the globe.   They are pos-
sessed  of considerable power as nervous stimulants, and are
pleasant beverages.   It  has  been  satisfactorily  demonstrated
  How may impurities be removed from water? How may the insipid taste of distilled wa-
ter be removed ? What are the objections to the use of sweet drinks ?  What is toast-wa-
ter, and what are its properties? Under what conditions of the system does oatmeal gruel
afford relief ?  AVhat are the general properties of tea and coffee ? 
TEA, COFFEE, AND  CHOCOLATE.
251
that they not only act as direct stimulants Avhen taken after
the performance of fatiguing work, but also prevent the waste
of tissues during labor, and are therefore of Aralue from an eco-
nomic point of vieAV.
   Tea was first imported into Europe by the Dutch  in 1664,
and is noAV  extensively employed as a drink by many nations
in the form of an infusion  of the leaf.   There are many varie-
ties of tea, but they  may  all be  reduced to tAvo orders, viz.,
green and black.  The varieties of the first class in  common
use  are  the hysons, imperial, and  gunpowder;  of the second,
the  souchong,  oolong, pekoe, pouchong, bohea, campo, etc.  An
analysis of tea shows that  it is composed of extractive, resin,
tannin, gallic acid, and mucilage, the greatest proportion of the
astringent principles  being  found in the green teas.  When
taken in too strong  an  infusion it produces restlessness and
Avakefulness, owing to its stimulating properties.
   Coffee was first  publicly sold in England in 1652.   The best
is that from Mocha, on the Red Sea ;  next in value is the Java;
while those from Brazil  are the poorest.  The value  of coffee
depends in a great measure on the care Avith which it is roast-
ed :  if the heat has been deficient in intensity, or has not been
continued long enough, it is bitter; if it is applied for too long
a period, all the aroma is expelled, and it is tasteless.  It is best
to grind and use it as soon as it is roasted, and when ground
'it may be  kept in closely-stopped bottles for  a considerable
period without deteriorating.   It is better to prepare it as an
infusion than as a decoction, for in the latter method the long-
continued application of heat expels the aromatic principle.
   Coffee is both tonic and exhilarant, and  is held in  high es-
teem by the student; it is regarded  as an  intellectual stimu-
lant, and has been  the brain-fuel of many distinguished authors
and litterateurs. When freshly made, and taken in small quan-
tity after a meal, it assists digestion;  but it should not be used
in excess, or mingled  Avith  sugar or  milk, as it is then apt to
produce indigestion.
   Chocolate is the pulp of the cacao or chocolate nut,  which is
roasted,  ground to a poAvder, and flavored with A^anilla, cinna-
mon, or other aromatics.  When prepared as a drink it is very
  AArhen and by whom was tea introduced into Europe? AVhat are the two classes of tea?
What are the constituents of tea ?  AVhich class of tea contains the largest proportion of
astringent principles ?  AVhat is the effect of the use of an excess of tea? When was coffee
introduced ?  AVhat is the finest variety of coffee ?  How is the berry prepared for use, and
what precautions should be taken in its preparation?  How may its aroma be retained?
What are the properties of coffee?  How should it be used after a meal?  AVhat is choco-
late ? 
252
THE  ALCOHOLIC LIQUORS.
indigestible, and should be avoided by all who have a tenden-
cy to dyspepsia.
  The soda-water made by condensing and dissolving carbonic
acid gas in Avater is a pleasant and agreeable drink, and. acts
as a gentle stimulant to the gastric mucous membrane. When
the powers of the stomach are reduced by the excessive use of
stimulants, or when there is prostration from over-excitement,
a little brandy mingled with the soda-water described above is
one of the best restoratives that can be employed, the carbonic
acid of the soda-water seeming to hasten the absorption of the
alcohol, as is shown by the rapidity with which the brisk wines,
as Champagne, produce an intoxicating effect.
                    LECTURE XLVIL
             ALCOHOLIC STIMULANTS AND TOBACCO.
Classification of fermented Liquors. — Times at which alcoholic Fluids
  should be taken.—Effects of the Abuse of alcoholic Drinks. — Prepara-
  tions of Wines.—Must.—Imperfection of our Grapes.— Composition of
  'Wine.—Its Bouquet.—Effect of Age.— Causes that Influence its intoxi-
  cating Power.—Port.—Sacks.—Sweet Wines.—Malt Liquors.—Liqueurs.
  —Liquors: Brandy, Whisky, Gin, Rum.
Tobacco, its Introduction.—Forms in which it is used.—Effects on the ol-
  factory Nerve.—Principles in Tobacco.—Effects of excessive Smoking.—
  Training.
  In the class of fermented liquors we include all varieties of
Avine, ale, and other  malt liquors, and the strong  spirits, as
brandy, whisky, etc.
  Alcoholic  fluids are of two classes—those which contain a
small percentage  of alcohol, such as  beer, ale, and the  light
wines, and those which contain  a great percentage, as brandy
and whisky.  The first are employed to such  an enormous ex-
tent by certain nations as  to have become  national in  their
character, the English and Germans resorting to the use of the
different varieties of  beer, the French  and South Europeans
employing claret and light wines, and the North Europeans
the strongest alcoholic liquors.
  Alcoholic fluids, when used  in moderation, belong  to the
class of respiratory food.   If taken before exercise or  labor
  Is it digestible?  AVhat is soda-water? How does it act when mingled with stimulants?
Give examples of fermented liquors.  What are the two classes of alcoholic liquors?  Whnt
nations employ the first class of liquors ?  What nations are habituated to the use of the
strong liquors ?  To what class of food do the alcoholic fluids belong ?
<v 
                   COMPOSITION OF AVINES.                253

they may be injurious, since they stimulate the individual to
undertake a greater amount of exertion than his system  can
bear.  The proper time  to  take stimulants Avithout  injury is
after the labor or Avork is finished, Avhen they aid in  restoring
the system to its perfect  state.
  The excessive use, or rather abuse  of alcoholic fluids, is, of
course, not  to be for a moment tolerated.  It not only for the
time converts the  man into a beast, but steadily undermines
the constitution, utterly  destroying the tissue  of the kidneys
and other organs, and producing such changes in the substance
of the brain as to cause incapacity and mania.
  Wines  are prepared from the juice of the grape,  Avhich is
called must.  This is caused to ferment at a certain  tempera-
ture, by which alcohol and carbonic acid are produced, the pro-
portion of alcohol obtained  depending on the amount of sugar
in the must.  In the juice of our domestic grapes the sugar is
deficient in quantity, and it is necessary to add a  sufficient
amount to exhaust the ferment in order to make a good Avine.
  When analyzed, Avines furnish the same constituents; in ad-
dition to alcohol, there is water, mucilage, tannin, coloring mat-
ter, various salts, and acetic acid.  The flavor  of the Avine is
called the bouqitet, and is probably due to an oily  compound,
Avhich in some A^arieties exists in the fruits, and in others is the
product  of the vinous fermentation.  Many wines, as sherry,
are  flavored by the  addition  of almonds.   The stimulating
properties depend in a great measure on the amount of alcohol
contained, as is shown by the following table from Brande :
	25-1		16-40	Tokay...............	... 10-
Port .	235 24-2		15-5 15-2	Elder Wine........	... 10-
					... 9-
	222		144	Cider............. 5-	to' 10-
Sherry, average...... Lachryma Christi.....	19-2		14-5		7- ✓
	197		8-9	Mead................	... 7-
	18-9	Rudesheimer, average	11-5	Ale.................5-	to 9-
Cape Madeira, aver-age....................	18*2		8-7		... 7-
			13-8	Porter...............	... 5-
	20*5		12-5	Small BeeiT........	... 1-2
	18-1		12-3		... 53-
White Hermitage.....	17-5		12 8		... 53-
	18-2		120	Scotch AVhisky...'.	.... 54-
Claret............12- to	17-5		11-2		... 54-
Age impresses great changes on wines, which render them
  At what time should stimulants be taken when they are needed by the system ?  What is
the effect of the abuse of alcoholic stimulants?  How are wines prepared?  What is the
name given to the unfermented grape-juice?  AA'hat governs the amount of alcohol in the
wine ?  A\That addition is necessary in the case of the grapes of the United States ? What
are the  constituents of wine ? What is the bouquet ?  Upon what ingredient do the stimu-
lating properties of the wine depend ? 
254          SACKS, SAVEET AVINES, AND LIQUEURS.

more valuable, and less liable  to produce hepatic  and renal
troubles.  The tartar, and a part of the coloring matter, are de-
posited in the form of a crust, and the alcohol either is united
with, or is converted into the oily material, so that the bouquet
is improved and the wine is less intoxicating.
  Burgundy Avines are far more heady than clarets, though the
proportion of alcohol is generally less; this is apparently due
to the peculiar character of their bouquet, Avhich is very power-
ful.  Of all the wines, claret is best adapted for ordinary daily
use, since it contains but little alcohol, and its astringent bitter
principles often aid a feeble digestive apparatus.
  Port  is chiefly used  in Great Britain, and  is especially pre-
pared by the addition of a large amount of brandy, to increase
the strength; tannin is also  added, to give the desired astrin-
gency, rendering it almost impossible to  find a pure article in
any part of the world, since these impurities are  added at the
vineyards to adapt it to the English  market.
  The sacks, or dry wines, in  which all the sugar is com^erted
into  alcohol, and of Avhich sherry is the most common example,
are in very  general use, and  are much less apt to  cause  gout
than port.   Many persons aa ho can not drink sherry without
an attack of indigestion can use Madeira with impunity.
  The  sweet wines, as Tokay  and Malmsey, differ from the
sacks in that they contain a  large quantity of sugar that has
not undergone fermentation.   They are not Avell adapted to the
stomachs of dyspeptics, and should only be used as cordials.
  Cider, perry, ale, and other malt liquors, are very extensively
employed, being in some countries national in their character;
and although the ultra fastidious may regard the malt liquors
as vulgar, they are nevertheless one of the best forms in which
a mild  tonic and  stimulant  action can be obtained in feeble
constitutions when they do not disagree, which is  often apt to
be the case, the large amount  of extractive they contain  render-
ing them very liable to take on an acetous fermentation.
  Liqueurs are made by adding sirup to an alcoholic solution
of various aromatics, as aniseed.  They should only be used in
very small quantity.  They sometimes contain narcotics, which,
added to the alcohol, renders  them much more noxious.
  The strong liquors, as brandy and whisky, are  obtained by
 What change  does age impress upon  wine?  Does the stimulating property  always
depend on the proportion of alcohol? How is port prepared for the English market?
What  are  sacks ?  Give examples of the sweet wines.  Upon  what  constituent  do the
malt liquors depend for their tonic properties ? AVhat are liqueurs, and how are they pre-
pared ? 
THE  USE OF TOBACCO.
255
distilling Avines or the products of fermentation of grain, and
condensing the alcoholic portions.   Brandy is prepared by the
distillation of AAunes.  Whisky, according  as it is  made  from
rye, or corn, or other grain, receives an appropriate designation.
That made from the potato is known as poteen.  Gin is an al-
coholic liquid, to which juniper berries have been added, though
the common article often contains turpentine.   Rum is  obtain-
ed by fermenting sugar or molasses.  All these strong  liquors
contain between  40  and 50 per cent, of alcohol, as is shown in
the table, page 253, and furnish respiratory food in its most con-
densed form.  They should  ahvays be  diluted, and used in
small quantity.

                          TOBACCO.
  This weed is said to have been first  sent to Europe in 1559,
and Avas introduced into England by Sir Walter Raleigh.  It
was at first much opposed by all the rulers and potentates of
Europe, yet, in spite of the  philippics  of James I., and  the ex-
communications  of Urban VIII., its fascinations have enabled
it to gain so strong a foothold that it can not now be expelled.
On its first introduction into Constantinople, where it is now in
universal use, any lover of the weed Avho Avas detected in the
act of using it was conducted through  the streets seated on an
ass, Avith his face turned to  the tail of his steed, and his nose
transfixed Avith a tobacco pipe.
  The use of snuff is perhaps the least injurious of  all the
methods of employing tobacco, 1 >ut when indulged in to excess
it is the most disgusting, and liable to produce dyspepsia.  It
sooner or later deadens the sensith^eness of the olfactory nerve
to such an extent that the sense of smell is lost, and the  Schnei-
derian membrane becomes thickened, giving the  voice a nasal
tAvang that is very disagreeable to a refined ear.  In  some
parts of the United States the Avomen use snuff to irritate  their
gums; this offensive practice passes under the designation of
dipping.
  Smoking is the most universal of all the methods of employ-
ing tobacco.   When first indulged in it is apt to produce nau-
sea and vomiting.  The active principles are nicotin and a vol-
atile oil.  The first is the most volatile, and therefore rises in
the smoke and enters the air-passages, Avhere it is absorbed by
  How are the strong liquors prepared?  How are brandy, whisky, gin, and rum  made?
When was tobacco introduced into Europe?  AVhat is the least injurious form in which it
can be used? AVhat is its ultimate effect on the olfactory nerve?  What is meant  by dip-
ping ?  What principles of tobacco are volatilized in smoking ? 
256           EFFECTS OF THE USE OF TOBACCO.

the blood.   When a person smokes to excess there is no longer
a mere  sedative action, but the nervous system is powerfully
affected, the hands tremble, and the action of the heart is inter-
fered with, palpitation being  induced.   It is also  stated that
the long-continued use of tobacco in any form, and especially
smoking, gradually blunts the virile powers, and finally renders
men impotent.
   Chewing is one of the most offensive methods of employing
tobacco, and is very apt to produce dyspepsia.
  Training, by which the athlete endeavors to put his body in
the best condition  for resisting fatigue, renders certain rules
compulsory.  They are:  to retire early;  to rise early; to exer-
cise freely in the open air, but not to produce fatigue; to eat
moderately of nutritious food;  to drink water, or a small allow-
ance of some malt liquor; and keep the mind gently occupied,
so as to be free from ennui; and if the person is an inhabitant
of the city, he should  remove to the country.
   In Avalking 1000 miles in 1000 hours," Captain Barclay lived
as follows.  He breakfasted, after returning from his  Avalk, at
five in the morning.   He ate  a roasted foAvl, and drank a pint
of strong ale, and then took two cups of tea, Avith bread  and
butter.   His lunch was at  twelve, and  it consisted, on alter-
nate days, of beefsteaks  and mutton-chops, of Avhich he ate a
considerable quantity.   He dined at six, either on roast beef or
mutton-chops, his drink being porter and tAvo or three glasses
of wine; and he supped at eleven on cold foAvl.  He ate such
vegetables as were in season, and the quantity of animal food
he consumed daily was from five to six pounds."
  What is their effect on the system when the tobacco is used to excess?  What is the ef-
fect of long-continued excess in the use of tobacco ? AVhat is meant by training ? 
CHANGES IMPRESSED ON  THE AIR BY ANIMALS.
257
                    LECTURE  XLVIII.
            HYGIENE OF THE RESPIRATORY SYSTEM.
 Changes impressed on the Air by Animals.—The Action of Plants.—The
  Black Hole at Calcutta.— The Black Assize at Oxford.—Effects of Car-
  bonic Acid on the System.—Inhalation of carbureted Hydrogen.—Fire-
  damp. — Choke-damp. —Effects of sulphureted Hydrogen. — The Action
  of Chlorine on  noxious Vapors.—Principles of Ventilation.—Methods
  of Warming by open Fires, by Stoves, and by Furnaces, with the Ad-
  vantages and Disadvantages of each.— Objections to the Use  of Steam-
  coils in Rooms.—Advantages of the Steam-heating Furnace.
  Animals are continually rendering the air impure by the
exhalation of carbonic acid, and the whole mass would be grad-
ually vitiated Avere  it not for the action  of plants, which undo
the work of animals, decomposing the carbonic acid they have
expired, setting its oxygen free, and restoring the purity of the
atmosphere.
  The history of the Black Hole at  Calcutta furnishes an il-
lustration  of the poisonous  character of the emanations from
the human body.   It Avas about  eighteen feet square,  and con-
tained one hundred and forty-six persons ; there was only one
small window, Avhich was  grated, and the atmosphere was very
sultry.  In less than an hour several of the prisoners  were de-
lirious and raved for water, which, Avhen given to them by the
sentinels, failed  to allay their thirst.  In  four hours many had
died, either by delirium or direct suffocation;  in another hour,
all except those at the windoAV were either dead or in a violent
delirium; and at the  close  of eleven hours only twenty-three
were alive, and these passed through a putrid fever before they
finally recovered.
  In the  Black Assize  at Oxford in 1577, a  prisoner  was
brought to the bar after having been confined in a small dun-
geon for some time.  He was placed betAveen the court and an
open window, so that the Avind  carried the emanations from
his  body toward the judges and jury, and many of them and
of the spectators Avere attacked with putrid fever and  died.
  The impurity Avhich is generally found in vitiated air is car-
  What change do  animals  impress on  air? How is its purity restored?  AVhat was the
history of the Black Hole at Calcutta?  AVhat was the history of the Black Assize at Ox-
ford?
                             R 
258             fire-damp and  choke-damp.

bonic acid; the effects of the inhalation of this gas are pain in
the head and singing or buzzing in the ears, loss of voluntary
power, and a strong tendency to sleep, disturbed respiration,
and palpitation of the heart.
  Carbureted hydrogen is also very noxious.  It is extensive-
ly employed as the illuminating gas of our houses and streets,
and is found in coal mines, being known to the miners as fire-
damp.  When mingled Avith air or oxygen it forms a mixture,
which, on the approach of a flame, explodes with such violence
as to destroy the mining  apparatus, and cause  the death  of
many workmen.  The products of the  explosion are vapor  of
water and carbonic acid,  Avhich is known to the miners  as
choke-damp ; it therefore is unsafe to enter a mine after an ex-
plosion until the  choke-damp has been  removed.
  The gas that accumulates in privies,  and such receptacles of
filth, is sulphureted hydrogen: when respired in the pure state
it produces almost instant death, and Avhen highly diluted it is
a powerful sedative.  The antidote is  chlorine; it acts  chem-
ically, decomposing the  sulphureted hydrogen with great  ra-
pidity.
  The  emanations from the bone-boiling and other establish-
ments Avhere decomposing animal refuse accumulates are com-
posed, to  a certain extent, of sulphureted hydrogen and offen-
sive vapors, all of AAThich  may be  destroyed by the action  of
chloride and other disinfectants.
  The  act of respiration is practically beyond  the influence of
the will.  We can not, for any length of time, increase  or  di-
minish the rate of respiration; but we can control the nature
of the air introduced into the lungs, and substitute for  a viti-
ated gas, redolent with disease, the pure, undefiled atmospheric
air, by resorting to a proper system of  ventilation.
   Ventilation is not generally understood, yet the principle on
which it is founded is perfectly simple, and readily applied to
any apartment.  It depends upon  the fact  that  if a given
amount of air is subjected to an  elevation of temperature, it in-
creases in volume, becomes lighter, and rises above the cool
surrounding air, which flows in to take its place.  We may
readily satisfy ourselves that Avarm or  hot air rises by ascend-
ing to the upper part of a room in Avhich a number of people
  AVhat are the effects of the inhalation of carbonic acid  gas ? What is the effect of the in-
halation of carbureted hydrogen ?  What is the difference between fire-damp and choke-
damp ?  What is the gas that accumulates in privies ?  How may it be destroyed ? Upon
what principle are the methods of ventilation founded?  How may we satisfy ourselves that
warm air ascends ? 
METHODS OF VENTILATION.
259
are assembled, or in Avhich numerous lights are burning, when
we find that it  is filled with a hot irrespirable gas which al-
most suffocates us.
   In  order to allow this vitiated air  to  escape, an  opening
should be made in the upper and another in the lower part of
the room, through which cold pure air may enter, to take the
place of the hot air as it passes out at the upper opening.
   It is the neglect to provide the  second opening that usually
renders attempts at ventilation so unsuccessful, for the Avarm
air can not pass out with any freedom unless there is  ample
pro vision for the introduction of fresh air to  fill the ATacuum
caused by the escape of that Avhich has become vitiated.
   The openings described  above are usually connected with
tubes or flues.   The flues, intended to afford a passage for the
vitiated air, should be built in the chimney, in order that they
may be kept warm, and thus insure a steady upward current,
Avhich may aid in ventilating the room at all times.
   When  a room is not provided with flues, excellent Arentila-
tion may be obtained by lowering  one half of a Avindow, to
make an upper opening, and raising the loAver half, to provide
the loAver opening.   In a bedroom it is best to adjust the win-
do av at the greatest distance from the bed, to aA^oid the  forma-
tion of draughts, Avhich may produce  rheumatism and other
diseases.
   The Ararious methods  of Avarming houses are intimately con-
nected with the subject of ventilation.   They may be divided
into three classes: 1st. By open fires; 2d. By stoves; 3d. By
furnaces.
   In the method by open fires, either of wood or coal, there is
an enormous loss of heat and consequent waste of fuel, more
than nine tenths of the heat produced by the combustion pass-
ing up the chimney, and only that portion Avhich radiates from
the front of the fire being utilized.   Another disadvantage is
the production of draughts  or cold  currents, Avhich flow in
through every cranny and crevice to fill the vacuum caused by
the passage of the heated air up the chimney, and which must
exist in order that the combustion may go on.
   The advantages are, 1st. A partial ventilation, since the open
ing of the chimney is in the lower part of the room; 2d. The
wanning  of the air  without  burning the fine  organic dust
  How many openings are required in order to ventilate a room, and where should they be
situated ?  How may we ventilate a room that is not provided with flues ? What methods
are employed in warming houses?  What are the objections to the method of warming by
open fires?  AArhat are the advantages attending their use? 
260
METHODS OF WARMING.
which floats in it;  but these are  almost counteracted by the
fact that one is obliged to keep continually revolving m front
of the fire in order to be Avarmed equally.
  In  the second  method the fuel is economized, and, if a long
pipe is attached to the stove, the greater portion of the heat is
utilized; but the disadvantage is the burning and charring of
the filaments  of organic matters that float in  the air of the
room, Avhich renders them more irritating to the  delicate mu-
cous membrane of the lungs.  The ventilation obtained by the
stove is also imperfect, since it draws the air from the parts ad
jacent to the  floor, and alloAvs the noxious gases to  accumu-
late.  It also has a tendency to render the air very dry, which
should ahvays be counteracted by keeping a vessel of Avater on
the stove, that moisture may be supplied  as fast as  it  is re-
quired.
  The objection  regarding draughts also exists in the use of
the stove, but to a greater extent.   The temperature of a room
warmed by a stove is higher than that of one  warmed by an
open fire; since, therefore,  the variations and contrasts  are
greater, the consequences are more severe.
  Under the  method of warming by furnaces we may classify
the ordinary hot-air furnace, the coil of steam pipes in  a  room,
and the hot-water or steam-heating furnace.  The  ordinary hot
air furnace has  many  advantages  over the method, by open
fires  and stoves; among these, the chief is the avoidance of
draughts, the tendency of the furnace being to  condense air
into the room, and so destroy all opportunity for the formation
of draughts by keeping continuous currents of Avarm air Aoav-
ing out at every crevice.                          9
   The  hot-air furnace also provides the means of obtaining a
most thorough ventilation by continually reneAving the air con-
tained in the  apartment.   The only valid objection to this sys-
tem  of Avarming is the liability to render the air irritating to
the lungs by  burning and drying it.  This may be avoided to
a great extent by proper attention to the condition of the fur-
nace, and supplying the hot-air chamber freely with Avater in
 shallow pans, in which cloths are  suspended, to provide  an ex-
tended surface from Avhich evaporation may take place.
   The use of steam pipes in rooms for the purpose of warming
is the Avorst of all methods  employed.   It is true it is conven-
  What is the advantage gained by warming with a stove ?  What are the disadvantages
 of the  second method of warming? How should the drying of the air be remedied? What
 are the advantages attending the use of the hot-air furnace ? AArhat  are the disadvantages?
 How may they be rectified?  What is the worst system of warming? 
AVARMING  BY FURNACES.
261
ient, economical, and cleanly, but all these advantages are nulli-
fied by the absolute Avant of ventilation Avhich  attends this
system.   The air of the room is ne\Ter changed,but is warmed
over and over again, rising to the top of the chamber, and then
passing over the heater when it has become cool, to be again
heated and breathed, so that on entering such an apartment
one is nauseated with the  foul odors that pervade it if it con-
tains many people.
   This method may answer  very  well, and be used with im-
punity in stores and shops where the <k»ors are being continu-
ally opened and fresh air introduced, but  it should be abol-
ished from hospital  wards and small bedrooms as being pois-
onous, unhealthy, and not  to be tolerated.
   The last method, by the  hot-water or  steam furnace, in which
the air is warmed  in  a chamber filled  Avith pipes,  through
Avhich steam or hot  water  is passing, is the best of all the sys-
tems employed, since it combines all the advantages of the hot-
air furnace in regard to the avoidance of draughts, and at the
same time warms the air without scorching it.
   We can not leave the consideration of the subject of \Tentila-
tion without draAving attention to the manner in which the hu-
man system gradually adapts itself to  the  increasing foulness
of a confined volume  of air.   An  example is afforded by the
manner in which a number of men will congregate together in
a room void of all means of ventilation, and continue to smoke
and drink for hours, with the windows  and doors closed, until
the accumulation of foul gases is so great  as to produce almost
immediate faintness in a person who enters the apartment from
the exterior fresh air, while those Avho haATe been present from
the commencement of the orgie seem to be unaffected.
  Though the system may adapt itself to the  use of a vitiated
atmosphere for a time, it is evident that it  must result finally
in reducing its tone and vitality, and favor the development of
many diseases.   It is doubtless oAving to the  unavoidable im-
purities in the  air of great cities that the inhabitants of such
places do n6t live  as long  as those who reside in the country,
and breathe the pure fresh  air of the woods and fields.
 Under what circumstances  may the  method of warming by steam coils in rooms be. em-
ployed ?  AAThat is the best method of warming ?  Can the system adapt itself to the use of
noxious gases ? AVhat is one of the chief causes of the shortness of life in cities ? 
262             CHARCOAL AS A DISINFECTANT.
                     LECTURE XLIX.
                DISINFECTANTS AND MALARIA.
Substances employed as Disinfectants.—The Peloponnesian Plague.—Ac-
  tion of Charcoal.—Malaria or Miasma.—Circumstances under which it
  is produced with greatest Virulence and Rapidity.—Is not the Result  of
  Animal or Vegetable Decomposition alone. —Evils cdtendmg the close
  Proximity of Trees to a Dwelling—Selection of a Building Site.—Rela-
  tive Power of dry and moist Air to convey Malarial and other Emana-
  tions.—Explanation of the Appearance  of Malarial Fevers on high
  Ground.—Means for  warding off the Access of Malaria.—Effect  of
  Change of Air on the System.—Action  of  Winds.—Time at which a
  Consumptive should Travel.
  When the air of a house, or given locality of limited extent,
has become impure  from the presence  of  decaying animal  or
other organic matter, it may often be purified by the use of dis-
infectants, such as carbolic acid, free chlorine, the  chloride  of
lime, or the  solution of chloride of soda.  On the great scale,
charcoal is  the best  disinfectant, as Avas demonstrated by the
fact  that the great fire  in London put a  stop to the plague
which was raging at the time  the fire originated.   It is also
the oldest known disinfectant, for we read that in the year B.C.
430, when, by the Peloponnesian War, Athens was crowded Avith
fugitives from the cities in the vicinity, a great plague broke
out, which Hippocrates stopped by causing immense fires to  be
lighted in all parts of the city and its vicinity.
   The disinfectant power  of charcoal is probably due to the
property it possesses of absorbing different  gases.   Of ammo-
niacal gas it will take up ninety times its  own volume;  of hy-
drochloric acid gas, ninety-five; and of other gases various pro-
portions.  Since  the deleterious poisons of fevers and plagues
exist in the gaseous state, or are disseminated through the  air
 in an exceedingly fine state  of subdivision, it is reasonable to
 suppose that  charcoal removes  them by absorbing them into
 its pores, just as it absorbs hundreds of other gases and vapors.
   The terrestrial emanations or malaria,  which are  generally
 supposed to produce fever and ague only, but which really pos-
   Name the substances employed as disinfectants.  How did Hippocrates stop the plague
 that followed the Peloponnesian War? To what property of charcoal is its disinfectant pow-
 er due ?  AVhat name is given to the terrestrial emanations that produce fever and ague ? 
ORIGIN OF MIASMATIC FEVERS.
263
sess the poAver of modifying, and even of originating many of
the diseases to which man is  heir,  and giving them a periodic
character, are still enveloped  in mystery.   They are generally
produced in marsh districts, but they also appear at times in
volcanic regions which are perfectly free from marshes, and do
not even contain springs or  any other natural waters.  It is
supposed by many that the malarial poison is  the product of
the decomposition of vegetable substances; but, if the presence
o£ vegetable matter is necessary, how are we  to account for its
appearance in volcanic  regions Avhere there is no  vegetable
matter for miles ?   In marsh lands the malarial poison is most
intense in its virulence when the water has all disappeared, and
the bed of the marsh so dried up that all decomposition must
have  ceased; and experience has  taught that if, in the very
worst regions, the ponds and rivulets are kept full of water, so
that  their beds are  not exposed,  there is very little danger.
There can be  no fouler odor or miasm than that Avhich ema-
nates from the hold of a sugar-ship, and yet it  has never been
known to create miasmatic fever.   We might continue to cite
numerous other instances to demonstrate the fact that the ma-
larial poison is not the result  of vegetable decomposition alone,
but, as  our space will not admit, Ave pass to  the consideration
of the theory that it  is  the product of animal putrefaction.
   If  miasmatic feA^er was caused in this manner, it should be
most  intense in the vicinity of the  establishments occupied by
" knackers," who are engaged in converting dead animals into
such manufactured articles as  ammonia, but Ave do not find that
even the "knackers"fere predisposed to malarial diseases; on the
contrary, they are usually strong and healthy in spite of the vile
odors among which  they live, and many reach the  advanced
age of eighty.  An epicure Avill eat the flesh of a bird that is
putrid, and yet no symptoms  of malarial fever  appear.  Medi-
cal students will breathe the offensive air of the dissecting-
room for months with  perfect  impunity.  We therefore. are
driven to the conclusion that  malarial fevers are not caused by
animal  exhalations alone.
   From the statements  made in the preceding paragraphs, we
see how imperfect our knowledge of the origin of miasmatic fe-
vers  is, yet there are certain well-established facts regarding
them  which are presented in the following quotation from one
  In what kind of soil do they prevail to the greatest extent ?  Is a marshy soil necessary to
the development of malaria ?   Is the malarial poison the product of vegetable decomposition
alone?  At what time does marsh land evolve malaria with the greatest rapidity? Is ma-
laria produced by animal decomposition ? 
264   CONDITIONS FAVORABLE TO DE\TELOPMENT OF MIASMA.

of our most distinguished medical authors :  " It may be stated
as a  general rule that houses in confined, shaded situations,
with damp courts or gardens, or standing water close to them,
are unhealthy in every climate and season, but especially in a
country subject to intermittent fevers, and during the summer
and autumn.  In our  own  country nothing is more common
than to see houses built in very unhealthy situations,  a  Icav
hundred yards distant  only from a good one.   Again, houses in
places otherwise unexceptionable are often so closely overhung
with trees  as to be  rendered far less healthy  residences than
they otherwise Avould  be.  Thick and lofty trees in the imme-
diate vicinity of a house tend to maintain the air in a state of
humidity by preventing its free circulation, and by obstructing
the free admission of the sun's rays.   Trees  growing against
the walls of houses, and shrubs in confined places near dAvell-
ings, are injurious also, as favoring humidity;  at a proper dis-
tance, on the other hand, trees  are favorable  to health.  On
this principle it may be understood how the inhabitants of one
house suffer from rheumatism, headache, dyspepsia, nervous af-
fections, and other consequences of living in a confined humid
atmosphere, while their nearest neighbors,  whose houses are
more  openly situated, enjoy good health; and even  how  one
side of a large building, fully exposed to the sun and to  a free
circulation of air, may be healthy, while  the other side, over-
looking damp shaded courts or gardens, is unhealthy.   The ex-
emption of the central parts of a large town from these fevers
is partly explained by the dryness of the  atmosphere which
prevails there, and the comparative equality of the  tempera-
ture.  Humid, confined situations, subject to great alternations
6f temperature between day and night,  are  most dangerous.
Of all the physical qualities of the air, humidity is the most in-
jurious to human life; and therefore, in selecting situations for
building, particular regard should be  had  to the circumstances
which are calculated to obviate humidity either in the soil or
atmosphere in every climate.  Dryness, with a free circulation
of air, and a full  exposure to the sun, are the material  things to
be attended to in choosing  a residence.  A person may, I be-
lieve, sleep  with perfect safety in the centre of the Pontine
Marshes by having his room kept well heated by a fire during
the night."

  In what situations is  malaria usually found?  Is a house  healthy when trees are close to
it? How do they act?  Are trees at a distance unhealthy?  What points should be partic-
ularly noticed in selecting a building-site ? 
              CONVEYANCE OF  MIASMATIC POISON.           265

  As odorous vapors and gases are conveyed to a greater dis-
tance by moist  air  than by that AAThich is diyvso, during the
day, the miasmatic  exhalations  are com^eyed in the aqueous
vapor that arises from the soil in Avhich they have been gener-
ated ; and at  night, when the  vapors  condense, the  miasmatic
poison is also deposited, and accumulates in the strata near the
surface  of the earth.   The lower stories of a building are there
fore rendered very unhealthy if the Avindows  are allowed to re-
main open during the night, while the windoAvs of the upper
stories may be left open with impunity, since all the malarial
emanations are  condensed in  the loAvest strata of the atmos-
phere.   In all dangerous districts it is unsafe to sleep on the
lower stories  of a house, and it is best in all localities to  have
the bedrooms on the second or third story.
  By the action  of winds, miasmatic poison may be carried to
considerable distances;  and it is  found, as  we might naturally
expect,  that  any thing  that tends to break the force of the
Avind, or turn it from its course, is a protection against malaria.
The presence  of a high Avail or screen of woods is often»an im-
passable barrier  to such emanations, and eAren a low hedge of
bushes  Avill frequently  turn them aside, and render localities
healthy AArhich Avould othenvise be uninhabitable.   So  perfect
is the protection afforded by fringes of bushes and forests, that
some suppose the leaves possess an affinity for the malaria, and
filter it out from the air in Avhich it is being conveyed.

                      CHANGE OF AIR.
  Our  physicians frequently  prescribe a  change of air  as a
remedial agent;  it is also one of the  best hygienic  stimulants
that can be employed.   When the mind and body are reduced
by  overwork, a slight change from the  city to the country, or
even from ,the country to the city, Avill often produce the  most
marvelous improvement in the general health, and reinvigorate
all  the  organs of the system to such  an extent as not only to
ward off an attack of illness, but even enable  us to undergo in-
creased labor, by furnishing a new lease of life and vigor.
  The  advantages of a  short  sojourn at any of our Avatering-
places  are well known, but the  majority  of people seem to
think they are chiefly due to  the nauseating waters that are
always  in the fashion at such places, AA'hereas, in reality, the
  Does moist or dry air convey odorous emanations to the greatest distance ? AVhy  are the
lower stories of a building the most unhealthy ? How may we explain the appearance of
malarial fevers on high ground ? How may the  access of the malarial poison be hindered ?
What is the effect of change of air on the system ? 
266
EFFECTS OF CHANGE OF  AIR.
salutary results are in a great measure the effect of change of
air, and the continued succession of gay scenes and pleasures
into which the invalid is obliged to enter to a greater or less
extent, and Avhich, by diverting his mind, give it rest, so that it
can recuperate; and with the improvement in the tone of the
nervous system, there is necessarily improvement in the general
health.
  The effect of winds is very similar to that of change of air,
for  they substitute  a pure atmosphere for that which is  stag-
nant and laden with poisonous emanations.
  When the system is already prostrated by a slow, lingering
disease, like consumption, great care should be taken in the se-
lection of the locality to which the sufferer should go.   It is a
very common  idea  that a trip to Southern Europe, and a so-
journ of a few months under the soft Italian skies, is one of
the best things that can be done; but, though it may be of ad-
vantage in the earlier period of the disease, it too often hastens
the final catastrophe in the latter stages, the separation  from
the comforts of home, and the absence of those who could cheer
and comfort the sufferer producing more harm than the change
of air does good.
  Certain islands have been long recommended as combining
many advantages for consumpth^es;  among them we may men-
tion Madeira  and the West Indies.   In  many cases great ad-
vantages are derived from a sojourn at these places in the win-
ter ; but the evil consequences of removal in the latter stages
of consumption are marked in the church-yards by the tomb-
stones that indicate the resting-places of those who sought re-
lief Avhen it was too late.
  To what causes may we attribute the improvement produced by a sojourn at a watering-
place ?  How do winds act on the atmosphere ?  At what period of consumption should the
patient travel ? 
EFFECT OF EXTREMES OF TEMPERATURE.        267
                       LECTURE  L.
                   HYGIENE OF THE SKIN.
Effect of sudden Changes of Temperature on the Mortality Lists.—Symp-
  toms of approaching Death from  Cold.—Southern Nations resist Cold
  better than Northern.—Time at which it is best to go into the cold Air
  from  a heated Room.—Effect of Moisture on the System.—Effect of
  desiccated Air on the Mucous Membrane of the Lungs.— Great solvent
  Action of moist Air on Emanations.—Application of Heat  to frozen
  Limbs.— Chilblain.—Effect of Climate on Nations.—Effects  of Light
  and Electricity on the Body.— Conveyance of Miasmatic Emanations
  by damp Air.—Effects of Winds on endemic and epidemic Diseases.
  Extremes of temperature are  very  unfavorable to  life, the
intense cold of winter increasing the mortality list among the
aged, Avhile  the  heats  of midsummer are  especially  fatal to
young people  and children.   Baron Larrey, who was Napo-
leon's  surgeon-in-chief during his campaign  in Russia in 1812,
states that during the nights of the  8th and 9th of December
the thermometer touched —27° and —32° Fahrenheit, and the
men and horses Avere struck with stupor if they took the slight-
est  repose, and died in great  numbers.  Many of the  soldiers
died Avhile on the march:  in these instances the countenance
first became pale, and  assumed an idiotic expression; speech
was imperfect and labored; the eyesight Avas dimmed, and oft-
en entirely obscured, but they continued to march along in col-
umn, supported by their comrades;  gradually the movements
of the muscles became more and more feeble; they staggered
as though they were inebriated, and, leaving the  column, soon
fell into the snow, whence they  could not  rise, but, being  at-
tacked by an overwhelming stupor, died in a feAv minutes.
  The same authority states that the  soldiers from Southern
Europe withstood the cold far better than those from Germany
and Northern Europe^ the former having  a higher hygienic
morale  than the  latter, who Avere specially liable to nostalgia,
or home-sickness, which is doubtless caused by the domestic
habits of the Germans, and all races that live in cold climates,
and Avhich  are poAverfully influenced  by their home  associa"
 What is the effect of cold and hot weather on the mortality lists ? AVhat are the symp-
toms of the approaching destruction of life by cold ? What nations resist cold best ? 
268
CHANGE FROM  HEAT TO  COLD.
tions, since they are obliged to rely to a greater extent on their
families for their happiness and cdmfort.
  Various opinions are held regarding  the effect of sudden
changes of temperature on the system, and many persons habit-
ually wait to  get  cool before they pass  from the hot atmos-
phere of a ball-room to the cold external air, fearing that the
sudden  change will be injurious.   It is true that there is seri-
ous risk in exposing the body to a great decrease in tempera-
ture, often in the winter from 80° in the ball-room to near the
zero of our scale in the  open air; but we must also remember
that if we pass into the air while the excitement still continues,
the powers of resistance are greater than when all such stimu-
lus is lost by a continued lingering in the dressing-room in or-
der to allow the temperature of the body to fall.  We can not,
therefore,  doubt that it  is best,  on leaving the  ball-room, to
dress warmly, with as much haste as possible;  and if we are so
fortunate as to have cheerful company on the way home, there
is but little danger to be feared.  In no part of the world is
the effect  of excitement in enabling the  system to resist cold
better known than in our own vicinity.  How rare it is for any
one  to  take cold Avhen they have indulged in a sleigh-ride;
the excitement of the rapid motion; the joyous jingling of the
bells; the merry song and merrier laugh being contagious, and
producing a degree of stimulation that is a protection against
the evil consequences of what would otherwise be a dangerous
indulgence.
  Though sudden changes from heat to cold can be borne with
comparative impunity, those  from cold to heat are very apt to
give rise to injurious consequences; an^ when the body, or any
part of it, has been chilled, the  application of heat  should be
gradual and cautious.   The  chilblain  is not produced by the
action of cold, but by the effect of heat on the chilled extrem-
ity.  Sometimes the inflammation runs so high as to terminate
in gangrene: such evil consequences may be avoided by apply-
ing heat gradually, the  best method being by  friction with
some cold substance.  It is said that in the north of Europe it
is  not an  uncommon incident for a traveler to be surprised in
the winter season by a stranger rushing up to him with a hand-
ful of snow, and proceeding  to rub his nose  in the most dis-
courteous and vigorous  manner, in order to restore the circula-

  At what time is it best to return home from a ball ? Why is it that people so rarely take
cold while  sleigh-riding?  Is a sudden change from heat to cold as dangerous as one from
cold to heat ?  How should heat be applied to a frozen extremity ? 
      EFFECTS  OF LIGHT AND ELECTRICITY ON  THE BODY.   269

 tion in the frozen feature.   Even in New York Ave occasionally
 hear, in very cold seasons, of persons Avho have lost their feet
 or hands by applying heat incautiously to these members Avhen
 they have been thoroughly chilled or even frozen.
  _ In the temperate regions the changes are more frequent and
 violent than in other climates, and we find the impress of the
 climate stamped on the character of the nations of the temper-
 ate zone.  As their climate is  variable, so they are subject to
 rapid variation in thought and  action.  They are compelled, by
 the  exigencies of nature, to meet sudden variations with suit-
 able  remedies, and, from  a mere attention to  the means re-
 quired  to render existence tolerable, they by degrees carry a
 system of observation and experiment into all their affairs, and
 pass their time in unceasing activity, while the inhabitant of a
 more favored  clime  is Avasting his life away in dreamy idle-
 ness.
   It  is not only necessary that fresh  air should be freely and
 abundantly  supplied, for light  is also essential to the proper
 development of  the body, as any one may satisfy himself by
 comparing the blanched, sallow, deformed child Avho Avorks in
 mines, with  the robust, ruddy, Avell-formed little one  Avho has
 his home among the green fields, and spends hours playing in
 the sunshine.
  The electric state of the atmosphere also influences the sys-
 tem, and though Ave may not be able to trace its method of ac-
 tion, Ave all know how the physical and mental sensations are
 influenced by an approaching storm.  The effects of the sudden
 discharge of a  large amount of electricity on or into the body
 is also well known to result in almost instantaneous death, and
 the bodies of persons who have been struck by lightning un-
 dergo decomposition more rapidly than those of persons who
 have died from other causes.
  The hygrometric condition of the air also exerts a poAverful
 influence on the condition of the system.   Air at all times con-
 tains moisture, AArhich may be detected by bringing it in con-
 tact Avith a cold surface, AArhen the vapor of Avater immediately
 condenses, and  covers the surface, as, for example, a pitcher of
 ice-water, Avith  drops of moisture.
  As Ave have demonstrated in Lecture XXL, a large propor-
tion of the egesta escapes from the body in the form of insensi-
  How does the climate of the temperate zone affect the inhabitants of that region ?  How
does light affect the body ? What is the effect of a sudden discharge of electricity on the
body ?   How does the hygrometric state of the air affect the body ?  How is the presence of
moisture in the air detected ? 
270      CONVEYANCE OF  EMANATIONS BY DAMP AIR.

ble perspiration or vapor.  When the air is laden Avith moist-
ure it can not so readily take up the vapor from the skin, and
we consequently feel the  heat more severely than when the
dew point is low, and there is less interference Avith the vapor-
ization  of Avater from the  system.   Under these circumstances
there is a tendency to the accumulation of effete materials in
the body, and consequently a greater liability to disease.
   Gay-Lussac found that  at great altitudes the proportion of
moisture in the air steadily decreased, and respiration is attend-
ed by disagreeable  sensations, caused, as he  supposes, by the
desiccating action of the dry air on the lungs.  A moist air has
a  greater solvent action OAer  A\arious mineral, vegetable, and
animal substances than a dry one.   In burning lime the work-
men find that the  carbonic acid gas is displaced with greater
facility on a damp day than on one Avhich is dry; they conse-
quently place in the ash-pit of the  furnace a  pan of water, the
steam from which, passing into the fire, aids in expelling the
carbonic acid.  The mineralogist avails himself of the  same
property of moisture when he causes the various clay-like bod-
ies to give out their peculiar odor by breathing on or moisten-
ing them;  and all must  have  noticed  the great  distance to
Avhich foul  odors  are conveyed in a fog, or just before a rain-
storm, when the air is highly charged with moisture.  The ma-
larial emanations from the earth are also in  many instances
carried to great elevations by the moisture that has been evap-
orated by the sun's rays, and after passing over many miles of
level land without producing any evil consequences, are finally
deposited on the high lands from the water that is condensed
in these regions by the decreased temperature that prevails,
and give rise to agues and other malarial diseases.  This is so
well known that the inhabitants of malarial districts  regard
the time at which  the dew falls  as the most  dangerous, and
carefully abstain from exposing themselves to its action.
   It is said that in  Africa, when the dry wind  blows from the
interior to the ocean, not only do the ordinary endemic diseases
leave them, but  those which  are  epidemic in  their character,
and even contagious diseases, as small-pox, also disappear.  If
this is true, and there is no good reason to doubt the veracity

  How does the air of great altitudes affect the respiratory apparatus ?  What was Gay-
Lussac's theory of its mode of action ?  Does moist or dry air possess the greatest solvent
power over emanations ?  Why is water placed in the pit of a lime-kiln ?  Give illustrations
of the power of moist air to convey odors with greater facility than dry air.  How do mala-
rial emanations reach great elevations ? At what time of the day is malaria most danger-
ous ? What is the effect of winds on endemic and epidemic diseases ? 
THE  ROMAN BATHS.
271
of the statement, it would appear that the humidity of the air
influences the properties of diseases, rendering them more dan-
gerous in some seasons than in others.
                       LECTURE LI.
         hygiene of the skin, Continued.—bathlng.
 Conditions essential for the proper Conduction of the Action of the Skin.
  — The Roman Thermce.—Action of pure Water on the Skin.— Use of
  Soe(p. — Abuse of Soap.— Cold Plunge-bath.— The Chill or Shock.—
  Use of the Cold Bath for Infants.— Conditions of the System in which
  Cold Baths should not be used.— Tepid Baths.—Adaptation of Tepid
  Baths to various Constitutions.—Warm Baths and their Action.—Hot
  Baths and their Action.—Flagellation.—Shampooing.—Turkish Bath.
  —Sea Bcdhing.—Effects of the long-continued App>lication of Water to
  the Skin.—Evil Consequences attending the sudden Stoppage of the Ac-
  tion of the Skin.
  The  skin being one of the great excretory  organs  of the
body, it is necessary that its function should be discharged in
a proper manner, in order that the system may be relieved of
the deleterious substances Avhich escape through the cutaneous
glands.  The hygienic  conditions to be  observed in  order to
accomplish this result are a due regard to cleanliness, and the
proper protection of the body by suitable clothing.
  It is  said that we may judge of the degree of civilization a
nation has reached by finding the per capita amount of soap it
consumes.   This may be very true as regards civilization, but
it is not necessarily the case regarding health, for Ave may abuse
the proper use of soap and of water to such an extent as to pro-
duce injurious consequences.
  Among the Romans the bathing establishments were Arery
magnificent, and  contained the frigidarium, or cold—the calda-
riam, or hot—the tepidctrium, or warm—and the vaporarium,
or vapor bath. They Avere also provided Avith the coxceluvium,
or hip bath; the manuluviuui, or hand bath; the pediluvium,
or foot bath;  the capitvluvium, or head bath;  the semicupium,
or half body bath.  We employ, in addition, the shower-bath,
electric bath, the dry bath  of hot ashes  and sand,  and finally
the animal bath, Avhich consists in wrapping the warm skin of
a recently-killed animal around the body.  In their great the?'-
ma?, or baths, the Romans also had the apoditerium, or dressing-
AVhat were the divisions in the Roman therma? ? 
 272     the effect of plunge and shower baths.

 rooms;  the unctuctrium, or perfuming-room; and a host of serv-
 ants, Avho performed special duties in the various  apartments.
 So solid and durable were the thermae, that in many cities they
 constitute the best preserved and most interesting  ruins ; they
 have also yielded to the modern museums many of the finest
 specimens of ancient art, the majority of the famous pieces of
 sculpture and mosaic having been found among the debris of
 the Roman baths.
   Water is the proper fluid to be used in washing the surface
 of the body, for it removes the soluble excretions  of the cuta-
 neous glands.   Soap is  also admirably adapted to the removal
 of dirt  of  every  variety that  may have accumulated on the
 hands or feet; but if it is used too freely on the general sur-
 face of  the body, it  dissolves the oily  exudation of the seba-
 ceous glands, Awhich  is required to enable the skin to retain its
 flexibility and softness.  The external  epithelial cells are also
 removed too rapidly when  soap is used in excess, and conse-
 quently the skin  is not  properly protected: it becomes subject
 to greater congestion in order  to reproduce the  cells and oils
 that have been abstracted, and is therefore more liable to cause
 disease  in the system when it is  suddenly subjected to the ac-
 tion of cold or draughts.
   The cold plunge or shower-bath is the best form in Avhich
 Avater can be applied to the whole surface of the body, when
the system can bear the shock; it then removes the  soluble
 salts that have been delivered on the surface by the sudoripa-
rous glands, accustoms the  skin to the sudden application of
cold, and gives a healthy  stimulus to its action  and to the
Avhole system.
  Since the temperature of Avells and springs is usually below
 60° Fahrenheit, and  that of the human body is about  100°, it
is evident that the cold  bath, in its first application to the sur-
face, must abstract a large amount of heat. The effect of this
loss of  caloric is  the production  of a chill or shock, in which
the skin is shrunken and bloodless, the internal organs over-
loaded Avith blood, the nervous  centres  rendered  torpid and
sluggish, and a general  sedative action  produced.  If, on leav-
ing the  bath, the  person steps into a warm room, and the body
is quickly rubbed dry, reaction comes on ; but if the bather is
 What is the action of pure water on the skin ? What is the object of using soap ? What
is the effect of employing an excess of soap ?  How does the cold plunge-bath act ? What
is the temperature of spring water  compared with that of the skin ?  What conditions attend
the production of a chill or shock ?  How should the reaction be brought on after a cold
bath ? 
THE  USE OF COLD  BATHS.
273
in the open air, and especially if the water is allowed to evap-
orate from the surface in a current of cool air or wind, the chill
produced Avill often overpoAver a Aveak person.  The tempera-
ture and circumstances under Avhich a bath is  taken must
therefore be modified to suit the condition of the bather, and
cold baths should not be employed unless reaction comes on in
a satisfactory manner when the body is speedily rubbed dry
after the bath.
  Many persons think that young infants should be hardened
by giving them cold baths and exposing them to cold air#  If
a child is strong and healthy it will stand a degree of exposure
Avith impunity, but if it is  weak or puny such treatment is
criminal.   In the words of John Bell," Cold bathing of tender
infants, with out regard to  constitution and temporary changes
of health, acts in a manner nearly analogous to the test of ni-
tric  acid on the metallic alloys: if gold be in them it remains
untouched, and  is exhibited in its nath^e brightness; the other
metals are corroded and dissolved.  So Avith the cold bath: the
feeble and valetudinary sink under its use, Avhile the  strong
and  robust are exhibited in a  more distinct point of view, and
are even benefited by their acquiring a  habit of endurance of
cold."
  In those Avho are suffering from acute cutaneous eruptions
the  cold bath will often prove injurious.   Those persons Avho
are  subject  or  liable to sudden internal  congestions  should
avoid the use of the cold  bath.  Females also, at  the time of
the  menstrual discharges,  should, as a rule, be very careful in
the exposure of their bodies to the action of cold.
  When the cold bath is followed by a  healthy glow over the
Avhole body it may  be freely used; but if  it produces a chill,
Avhich continues  even though the body  is  Avell rubbed, it
should be avoided, and tepid or warm baths substituted.   Tep-
id baths are sometimes debilitating in their action; but since
there are certain constitutions Avhich can not bear the sudden
application of cold, the use of warm wrater  is sometimes neces-
sary for the purpose of cleansing the surface of the skin.  When
tepid baths are employed, the time the  person remains in* the
bath should  not be more  extended than is required to wash
the surface of the body.
  Is the indiscriminate use of cold baths for young infants justifiable ? Should the cold bath
be used by persons suffering from acute eruptive diseases ? Should it be employed by wom-
en when  they are menstruating?  Under what conditions should the cold bath be used?
How do tepid baths act ?  How long should a person remain ia a tepid bath ?
                             s 
274          ACTION OF TEPID AND HOT BATHS.

  The tepid bath should have a temperature from 75° to 90°;
it is admirably adapted to constitutions in Avhich the shock of
the cold bath is injurious.  It may be adjusted to all constitu-
tions by first immersing the body in water which is very near
the temperature of the system, and then cooling it five or ten
degrees, and repeating the immersion; and, if it  is desirable,
the same process may be again repeated.
  The warm bath  should have a  temperature of about 95°;
when the circulation is languid the temperature  may be two
or t^ree degrees higher, and if it is active  it may  be a few  de-
grees loAver.  It is  especially grateful when the body is  ex-
hausted by the fatigue of labor or travel, since it  removes the
accumulated secretions of the skin, and reinvigorates the sys-
tem without subjecting it to a shock.   For old people and in-
fants the warm bath is preferable to the cold, and the dryness
of skin from which many old people suffer is often relieved by
using the wTarm bath two or three times a week.
  The effect of the Avarni bath on the organs of circulation and
respiration is sedative, the rate of pulsation and respiration be-
ing diminished, and the  capillaries  of the skin relaxed,  the
blood flowing with greater ease and freedom to all parts of the
system.
  In the hot bath the temperature of the water is above 9.8°;
its action is stimulating, since it  adds to the heat of the body,
and  excites the circulatory and nervous systems  to an extent
that is often injurious.   The plethoric condition of the body
under the excitement is shown by the swelling of the fingers,
the rings that are worn producing an  uncomfortable degree of
pressure, and such symptoms as  vertigo, palpitation, and faint-
ing being often superinduced; these  pass  away on leaving the
l>ath, and are followed by a free perspiration and a sense of ex-
haustion.
   In some countries certain manipulations are considered to be
necessary accessories to a bath.  The Russians submit the body
to a course of flagellation with birch twigs in order to excite
the  cutaneous capillaries.  Frictions  are employed by others,
but  the operation of shampooing is perhaps the most complex;
it was originated by the Hindoos, and is described as follows:
" One of the attendants on the bath extends you upon a bench,
sprinkles you with warm water, and presses the whole body in
  What should 'be the temperature of a tepid bath ?  How may it be  adjusted to various
constitutions ? What should be the temperature of the warm bath ? What is its effect on
the system ?  What is the temperature of a hot bath ?  How does it act ? What state  of
the system follows the hot bath? What is flagellation? What is shampooing? 
                SHAMPOOING  AND  SEA-BATHING.            275

an admirable manner.  He cracks the joints of the fingers and
of all the extremities.   He then places you upon the stomach ;
pinches you oyer the kidneys;  seizes you by the shoulders and
cracks the  spine by agitating all the vertebrae; strikes  some
powerful blows over the most fleshy and muscular parts; then
rubs the body Avith a hair glove until he sAveats; grinds down
the thick, hard skin of the feet with pumice-stone; anoints you
witli soap;  and, lastly, shaves you, and plucks out the superflu-
ous hairs.  This process continues  for three quarters of an hour,
after Avhich a man  scarcely knows himself; he feels like a new
being."   In Eastern countries, where the  use of the Turkish
bath prevails, the bather is subjected to all the above process-
es, and at the close of the operation the surface of the body is
anointed Avith some oleaginous substance, to protect the skin
from the consequences of such harsh treatment.
   Sea-bathing differs  from the fresh-water  bath not only in
the presence of saline materials in the water, but also by the
exciting circumstances by  which it is surrounded.  To use the
words of Bell: " If Ave merely had regard to the temperature
of sea-Avater, Ave should consider immersion in it as simply cold
bathing; but there are  circumstances connected with the act
which modify materially  its effects.   Sea-bathing is usually
preceded by some  exercise, a walk or ride to the beach; it  is
accompanied by some muscular exertion-—struggling against
the waves, or, in the more robust, by attempts to swim.  With
others, again, the whole affair is attended by a dread of danger,
Avhich powerfully affects the nervous system, and causes hur-
ried breathing, palpitation, and increased rapidity of the circu-
lation, all of Avhich tend to change materially the character of
the bath, and render the bath in the air, whether in the sea, or
in river or lake water, A^ery complex in its  action when com-
pared Avith  the ordinary house bath."
   In order to reduce the effect of  the shock in the bath in the
open  air, it is best to immerse  the  whole  body as quickly as
possible; in this manner the uncomfortable sensations that at-
tend the  gradual immersion of the body are avoided.  The
best time to bathe is also a matter of interest; the bath before
breakfast is no doubt the most Avholesome, since at all other
periods the stomach is more or less engaged in the process of
digestion.   The length of time a person should remain in the

 What is the final operation in the Turkish bath ?  How does sea-bathing differ from the
fresh-water bath? How may the shock be reduced in bathing?  What is the best time to
bathe ? 
276  EFFECTS OF LONG-CONTINUED APPLICATION OF  WATER.

water is a question that must be determined by every one for
himself, but, as a rule, five or ten minutes is sufficient, and the
body should be well rubbed Avith a rough towel on coming out.
  The long-continued application of water  is apt to result in
reducing the vitality of the skin to so low a degree as to cause
numerous ulcerations  and boils.  In some people such eruptions
may remove deleterious substances from the body, but the ex-
perience of the majority shows that they are the product of the
debilitating action of the water  on the glands of the skin, and
unless the  abuse of that liquid is discontinued the most disa-
greeable consequences may  ensue.
  In some persons the glands in the armpits and other parts
of the body secrete a fluid possessing a disagreeable odor, and
it often happens that the attempts to remove it by the free use
of soap and water result in its increased production, and the se-
cretions are rendered  more offensiA^e.
  It must not be supposed that  we object to the proper use of
water in Avhat has been said in the preceding paragraphs; it is
only intended to draw  attention to its abuse, and  to the pecul-
iarities  of the systems of some indiAnduals,  for the majority of
men are benefited  by the use of daily baths.  It is a matter of
Avhich every individual must judge for himself, and determine,
by experiment on  his own person, how often and what variety
of bath should be  employed.
  Sudden variations  in temperature and in the dew point are
apt to check the action of the skin;  draughts of air from small
creATices produce the  same result, while a strong wind is often
harmless.  The sudden stoppage in the action of the skin causes
the effete materials Avhich it is  its function to excrete, to. accu-
mulate in the  system, until finally they seek an  exit through
some other channel,  such as the lungs or kidneys, and, acting
as irritants to these organs, produce the numerous inflamma-
tions which arise from  exposure and cold.
  How long should a person remain in the water?  What is the effect of the long-continued
application of water to the skin ? What is the effect of the sudden stoppage in the action
of the skin ?  What causes affect the action of the skin ? 
EXPERIMENTS  OF DAVY.
277
                       LECTURE Ln.
              HYGIENE OF  THE SKIN.--CLOTHING.
Materials employed in the Manufacture of Clothing. — Experiments of
  Davy on the conducting Power of various Textures.—Influence of Pack-
  ing on the conducting Power.—Summer and Winter Clothing.— Use of
  Flannel.—Exemption of the  ancient Romans from Malaria.— Captain
  Murray's Experiments with Flannel.— Use of Flannel by the Aged and
  Infirm.— Use of Stockings. — Changing of Under-clothing. — Clothing
  should be well aired.—Scotch Method of airing Clothing.— The Cut or
  Shape of the Clothing.—Adaptation  of the Shape to the Climate.— Use
  of Corsets.—Experiments of Dr. Stark on the absorptive Power of Tex-
  tures of different Colors.
   In order to enable the skin to continue its function with reg-
ularity, it should be protected from sudden changes of temper-
ature by means of suitable clothing.  The materials  employed
for this purpose are linen,  cotton,  wool, and silk.
   Sir Humphrey Davy made a very  interesting series of exper-
iments to determine the conducting poAver of these  materials.
The method he employed Avas to fill  a glass flask Avith the sub-
stance under examination, and, introducing a thermometer with
its bulb  resting at the centre of the  flask, the  arrangement
was then immersed in a vessel of boiling water, and the time
required to raise the index liquid of the thermometer a given
number of degrees determined.   Submitting various textures
to  this test, he found that linen  was the best conductor, then
cotton, wool, and silk, in the order mentioned, silk  being the
Avorst.
   Davy  also  found that the closeness of packing influenced
the conducting power by  entrapping a greater or less amount
of air  in the meshes of the tissue.   When it was tightly packed
the conducting power was improved, while loose package di-
minished the conductibility.  In weaving cloth the textures in-
tended for winter use should therefore be loosely woven; those
to be  employed in the summer should be closely woven.  Lin-
en and cotton goods, being the best conductors, are suitable for
  AVhat materials are emploved in the manufacture of clothing ? Describe the experiments
of Davy  on the conducting power of different tissues. AVhat is the order of the conducting
power of different tissues ?  AVhat is  the influence of variation in package  on conducting
power?  How should summer goods be woven ? 
278                   USE OF FLANNEL.
summer use in hot climates, while woolen and silk goods should
be employed in the winter season in cold climates.
  Many discussions have from time to time arisen as regards
the healthfulness  of various textures used as under-clothing.
The oldest, most enduring, and perhaps the best, is linen.  We
find it mentioned in the earliest works, and ft  is even  now
found in the cerements enveloping the mummies  that were in-
terred thousands of years ago in the tombs of ancient Egypt.
  It is not only necessary that the body should be protected
from the direct action of the variations in the seasons, but care
should be taken not to expose it Avhen it has been heated by
violent  exercise.  During the continuation of the exercise it
may be exposed freely; but when exercise has ceased, and it is
bathed with  perspiration, and the skin is  congested, it should
be protected from the injurious action of draughts and currents
by  some suitable covering.
  When the occupation of the individual subjects him to fre-
quent changes of temperature, experience has taught us  that
the best material to use next the skin is avooI in the form of
flannel; it protects the body from the sudden  changes to which
it is liable, and absorbs the perspiration as fast as it is secreted
without producing a disagreeable sensation of chilliness,  as is
the case with linen and cotton.
  By some the use of flannel next the skin is held in such  high
esteem that  they have even  attempted to show that in  past
times the Romans suffered less from the malarial fevers because
they incased their bodies in warm materials made of wool, and
it has been thought that the sheep and other  animals that feed
during the night on the Campagna OAve their freedom from ma-
larial disease to the dense covering of wool or hair with which
Nature has provided them.
  The advantage of wearing wool next the skin is properly
appreciated among army and navy  officers; and  Captain Mur-
ray, of the British ship Valorous, relates " that he Avas so strong-
ly impressed, from former experience, with a sense of the effi-
cacy of the protection  afforded by the constant use of flannel
next the skin, that when, on his arrival in England in Decem-
ber, 1823, after two years' service amid  the icebergs  of the
coast of Labrador, the ship was ordered to sail immediately for
  What is the best material to wear next the skin? Should the body be exposed while the
skin is congested ?  What is the best material to wear next the skin when the bSdy is obliged
to be submitted to sudden changes of temperature ?  What opinions have prevailed regard-
ing the exemption of the ancient Romans from malarial fevers? What was the experience
of Captain Murray regarding the use of flannel in hot and cbld climates ? 
Murray's  observations.
279
the West Indies, he ordered the purser to draw two extra flan-
nel shirts and pairs of draAvers for each man, and instituted a
regular daily inspection to see that they were worn.   These
precautions are stated to have been followed by the most hap-
py results.   He proceeded to his station with a  crew of one
hundred  and fifty men; visited  almost every island in the
West Indies, and many of the ports on the Gulf of Mexico;
and, notwithstanding the sudden transition from extreme cli-
mates, returned to England without the loss of a single man,
or having any sick on board on his  arrival."  He also adds
"that  every*precaution Avas used,by lighting stoves betAveen
decks  and scrubbing Avith  hot sand, to insure the most thor-
ough dryness, and  every  means  put in practice to promote
cheerfulness among the men.  When in command of the Re-
cruit gun-brig, which lay about nine weeks at Vera Cruz, the
same means preserved the health of his crew, when the  other
ships of Avar anchored around him lost from twenty to fifty
men each; and although constant communication was maintain-
ed 1 >etween the Recruit and the other vessels, and all were ex-
posed to the same external causes of disease, no case of sickness
occurred on board the Recruit."
   When flannel is first put on it often causes an exceedingly
unpleasant itching, which may be avoided by wearing linen or
cotton under it; but the practice should be  avoided if possible,
for it seriously interferes with the hygienic properties  of the
flannel,  Aged  and infirm people should wear it all the year;
and if those who are subject to rheumatism, or predisposed to
grave  pulmonary disease, would  adopt the same practice, it
would be greatly to their advantage.
  Stockings, though a modern discovery, have become an indis-
pensable article of clothing for adults.  The singular effects of
exposure of the feet to cold and Avet are known to all, yet how
careless most people are in this  particular, and how bitter]}
they regret their neglect Avhen a seATere catarrh or rheumatism
is the  penalty which  outraged nature exacts.  In childhood
many seA'ere attacks of disease might be aA^erted by keeping
the feet Avarni and dry; and as middle and old age approach
the precaution becomes more necessary, for the poAvers of the
system to throAV off disease  are less, and, since prevention is al-
Avays better than cure, it is best to don the winter woolen on
the first appearance of cold  weather.
  How may the itching that attends the use of flannel be avoided?  AAThy should especial
care be paid to the protection of the feet? At what time should woolen clothing be put on ?
« 
280
USE of  corsets.
   The garments that are worn next the skin should be changed
 before they become saturated Avith secretions of the sebaceous
 glands.  This  can be accomplished by renewing them about
 twice a week, though the majority of people only change them
 once in the same period; but it is not sufficient.   Clean cloth-
 ing should always be well aired and dried, especially in the
 case of invalids.   It is said that in Scotland, Avhen a poor sick
 person is ordered a change of linen, it is the custom for a friend
 or relative to wear it for some  days in  order that it may be
 well etired.  The effect of such a system is to render it utterly
 unfit for use, for it is permeated with the secretions of the skin
 of the first wearer; and, if he has been in the vicinity of, or is
 himself suffering from any contagious disease, it is very liable
 to be imparted to  the  sick man.
   The shape or cut of the clothes has a certain amount of influ-
 ence on the health of the wearer.  In hot countries they should
 be ample and loose, so that the air they contain may be readily
 and frequently changed, and the emanations from the skin  re-
 moved.  Illustrations  of this  principle are afforded by the Per-
 sians, Arabians, and all nations that live  in hot countries.   In
 cold climates, on the contrary, the clothes  are nearly ahvays cut
 so as to fit the body  closely, and retain  the heat as  much as
 possible.
  As regards the  use of ligatures around any part of the body,
 whether as "stocks or  tight neck-ties in  men, or tight  corsets
 and garters in women, we  can only speak  in condemnation;
 but ^ so long as the fashions of America are  originated  by the
 Parisian lorettes, it is useless to attempt to resist any absurdity
 they may introduce.   For the sake of those who think they
 must  employ some such article of dress, Ave quote the  recom-
 mendations of Dr. G-oddard, in his essay  on  tight lacing.   He
 says :  " 1st. Corsets should be made of smooth, soft, elastic ma-
 terials ; 2d. They^  should be  accurately fitted, and modified to
 suit the peculiarities of figure of each Avearer; 3d. No other
 stiffening should be used but that of quilting or padding:  the
 bones, steel, etc., should be left to the deformed or diseased, for
 Avhom they were originally intended; 4th. Corsets should nev-
 er be draAvn so tight as to  impede regular natural breathing,
 as, under all circumstances, the improvement of figure is insuf-
  How often should the garments next the skin be changed ? Why should clothing be aired
before it is put on ?  What cut or shape should be given to the clothes ? AVhat difference
in the method of cutting should be employed in different climates ?  Are corsets and such
 means of compression healthy ?  How should corsets be constructed and worn when thev
are used ?
• 
       ABSORPTION OF EMANATIONS BY  DARK  CLOTHING.    281

ficient to compensate for the air of awkward restraint caused
by such lacing; 5th. They should never be worn, either loosely
or tightly, during the hours  appropriated to sleep, as, by im-
peding respiration, and accumulating the heat  of the system im-
properly, they invariably injure; 6th. The corset for young per-
sons should be of the simplest character, and worn in the light-
est and easiest manner, allowing the lungs full play, and giving
the form its full opportunity for expansion."
   We have, in a previous lecture, drawn attention to the ex-
periments of Franklin and Davy, which demonstrated that dif-
ferent-colored surfaces absorbed light with different degrees of
rapidity; Ave  now advance those of Dr. Stark on the power of
cloth of different colors  to absorb odors.  The sense of smell
shows that Avhen portions of cloth of various  shades are ex-
posed to odorous gases or vapors, those which are darkest ab-
sorb the odoriferous particles with the greatest avidity.  By
employing camphor, Stark added  ocular proof of the fact  that
the power of colored surfaces to  absorb  odorous particles de-
pends on tin1  depth of the color, those which  are dark absorb-
ing often more than twice as much as those which  are of a
light tint.   To quote his own language: " If it be thus certain
that odorous emanations have not only a particular affinity for
different substances, but that  the color  of these  substances ma-
terially affects their absorbing or radiating quality, the knowl-
edge of these  facts may afford useful hints for the preservation
of the general health during the prevalence of contagious dis-
eases.   From  their minute division and vast  range of action,
latent poisonous  exhalations  or effluvia, inappreciable by the
balance, may no doubt exist to a dangerous extent without be-
ing evident to the sense of smell.  But  in most cases  it will be
found that, Avhen  contagious diseases prevail to such an extent,
the emanations from the  sick will, if attended to, give the surest
indications of the contamination of the surrounding air.  Be-
sides, even if Ave alloAv that infectious emanations have no  nec-
essary connection Avith odors, the experiments will afford the
strongest possible presumption that the emanations  of an in-
fectious nature, in  common. Avith odors, vapors, and emanations
generally, are  emitted on the  one hand, and,  on the  other, re-
ceived according to the same general laAvs.  Next, therefore, to
keeping the Avails of hospitals, prisons, or apartments occupied
by a number of individuals of a Avhite  color, I should suggest
 AVhat were the experiments of Stark on the absorptive power of textures of different col-
ors ? 
282                 EFFECTS OF  EXERCISE.
that the bedsteads, tables, seats, etc., should be painted Avhite,
and that the dresses of the  nurses and hospital  attendants
should be  of a light color.   A regulation of this kind would
possess the double advantage of enabling cleanliness to be en-
forced, at the same time that it presented the least absorbent
surface to the emanations of disease.
  " On the same principle, it would appear that physicians and
others, by  dressing in black, have unluckily chosen the color
of all others  the most absorbent of odorous and other exhala-
tions, and  of course the  most dangerous to themselves  and pa-
tients.  Facts have been mentioned which make it next to cer-
tain that contagious diseases may be communicated to  a third
person through the medium  of one Avho  has  been exposed to
contagion, but himself not affected."
  Though Ave may not accept all that Dr. Stark has stated,
there can be  but little doubt that dark-colored surfaces do  ab-
sorb odorous and other emanations with  greater avidity than
those which  are light, and his recommendations regarding the
dresses of hospital nurses and patients are worthy of serious
attention.
                      LECTURE LIU

 HYGIENE OF THE MUSCULAR, OSSEOUS, AND NERVOUS  SYSTEMS.

Exercise necessary to the proper Maintenance of the Muscidar and Nerv-
  ous Systems.—Forms  of Exercise. — Active and Passive  Exercise.—
  Walking. — Leaping. — Running. — Dancing.— Fencing. — Boxing.—
  Wrestling.—Horseback Exercise.— Sailing.— Driv ing.— Passive Move-
  ments of different Limbs.—Amount of Exercise required by an Adult.
  —Incompatibility of Labor and Mental Activity. — Conditions requi-
  site for the proper Development of Bone.

  In order  to preserve the muscular and  osseous  tissues  in a
perfect state of health, the first must be subjected to a certain
amount of exercise, and the food must be adapted to the prop-
er nutrition of the latter.
 ^ Exercise, to a suitable extent, is one of the essential condi-
tions of health; it not only improves the tone  of the muscular
system, but it also imparts a stimulus to all the tissues and or-
gans  of the body.   Its  action on the  digestive apparatus is
universally  known, and  is appreciated to a greater or less ex-
tent by all.
 What should be the color of the  clothing of nurses? AVhat are the conditions necessary
to the proper maintenance of the muscular and  osseous tissues ? 
FORMS  OF ACTIVE EXERCISE.
283
   Exercise may be either  active or passive.  In the first the
muscles  are thrown into action by the will of the individual;
they  consequently are nourished with greater perfection, in-
crease in size, and become  firm and hard, and are capable of
enduring an immense  amount of fatigue and labor.   The fat
that fills the  interstices betAveen the  bands that compose the
muscles, and that between the muscles themselves, is absorbed,
and the outlines of these organs are sharply defined, and, at the
same time, the limbs gain greater freedom of action.  In pas-
sive exercise, on the contrary, the source of motion is extrane-
ous to the body, and it is subjected to a  series of forced move-
ments ; the organs of the system are stimulated by the succes-
sion that attends these movements, and the muscles are thrown
into  activity that varies with the intensity of the original
cause.  In riding on horseback, for example, a very considera-
ble amount of muscular exertion is necessary in order to retain
one's seat when the motion is rapid.
   Of all the forms of active  exercise, that which is attendant
on travel is the  most beneficial, on account of the constantly re-
curring changes of air, and the continual stimulation of the
senses by the numerous novelties that are presented in rapid
succession.  With the improvement in the tone of the nervous
system that folloAvs on this grateful stimulation of the senses,
there is increased appetite;  the traveler eats heartily and sleeps
soundly; digestion and absorption are benefited, and the  tone
of all the tissues and organs elevated.
   The gentlest  form  of active exercise is walking  on a level
surface;  the muscles of the extremities, trunk, abdomen, and
neck are thrown into a moderate action, which does not easily
produce  fatigue.  In ascending and descending a hill-side the
motion  is  more violent and the succussion is greater, conse-
quently fatigue  is more rapidly induced.
   Rowing is an  excellent form of exercise, which may be adapt-
ed to all periods of life, from the mere child to the old man.
It is of great value to young men, since it tends to develop the
muscles  of the  chest; and when the  exertion is great, as in
racing, nearly all the muscles  of the body and lower extremi-
ties are also thrown into violent action.
   The exercise  of leaping or jumping jars the body violently;
it is only suitable to the period of youth, when  the cartilages

  What are the forms of exercise ? How does active exercise act ? How does passive ex-
ercise act ?  What form of exercise is most beneficial ?  What is the gentlest form of exer-
cise ?  How does rowing act ?  How does leaping act on the organs ? 
284             FORMS OF PASSIA^E  EXERCISE.
are soft, and can, by their elasticity, moderate the Auolence of
the succussion.   In  adults and in old people, in whom the car-
tilages have become indurated, and have lost, to a certain ex-
tent, their elasticity, it is highly improper, and is frequently
followed by serious  consequences.
   In running there is a succession of leaps, which quickly pro-
duces fatigue, and excites the organs of circulation and respira-
tion violently; it is also  only suited to the earlier periods of
life
   Dancing  is a compound of stepping and leaping, frequently
attended by a movement of gyration, and diversified with pe-
riods of rest; the mind is at  the same time stimulated by the
music, and the brilliant costumes and merry faces aid in  mak-
ing it one of the best forms of exercise when not carried to  ex-
cess.  Where there is any organic disease of the heart or lungs
it should be avoided, and during the periods of gestation and
menstruation it is apt to  produce serious consequences.
   Fencing rapidly develops all the muscles of the upper  ex-
tremities, and of the trunk and loAver extremities.  It also  ne-
cessitates great activity of the mind and senses, in  order to
guard against the attack of the opponent.  Boxing and wres-
tling  are  very similar in character to fencing;  they  are  only
adapted to the periods of youth and manhood.
   Of the forms of passive exercise Ave have already stated that
horseback riding is the best;  next to this we may place riding
in a carriage, which  may be varied in the intensity of its effect
by the nature of the vehicle.
   Sailing is another  form of passive exercise, the effect of Avhich
depends in a great measure on the  change of air and continued
succession of novelties, but which also brings to some the long
train of uncomfortable sensations included under the  name of
sea-sickness, the explanation of Avhich is  still involved in  mys-
tery ;  but, in spite of this drawback, it is one of the best forms
of exercise for the majority of urvalids, and is often one of the
best remedial  agents  that can be  employed during  convales-
cence.
   When the system is debilitated by disease it is often incapa-
ble of any  of the modes  of exercise mentioned  above; under
these  circumstances,  gentler forms  of movement  are often pro-
ductive of excellent  results.  If the sick man is too weak to
  How does running act ? At what periods of life should leaping and running be indulged
in?  Under what circumstances should dancing be avoided?  How does fencing act__box-
ing—wrestling ?  What is the best form of passive exercise ?  How does sailing act ? 
     REACTION OF THE  MIND AND BODY ON EACH OTHER.  285

ride in a carriage, the use of passiA^e motion, in Avhich the limbs
are moved by another person, and the skin gently rubbed, aatII
be found to aid in improving both the appetite and the action
of the different organs.
  The amount of exercise required by different persons varies
greatly, but a Avalk of four or six miles a day  seems to agree
Avith the constitutions  of the majority of men; they eat  and
sleep  better, and all the functions  of their  systems are  per-
formed with greater satisfaction when a certain amount of ex-
ercise is  taken daily.  But no definite rule can be established;
every individual must  experiment for himself, and determine
the amount of physical exertion necessary for the well-being of
his OAvn  system.
   Exercise is, of course, a subject of no interest. whatever  to a
laboring man; but to those who follow sedentary pursuits  it is
of vital importance, and especially to the student, Avho is only
too apt, when carried aAvay by the desire to attain mental and
intellectual improvement, to forget the absolute necessity of
paying some attention to the Avants of the body.   It is to this
class that we would earnestly appeal, and urge the necessity of
spending one or two hours a day in outdoor exercise, that their
bodies may be fitted to bear the strain Avhich the nervous sys-
tem is compelled to endure.
   It  is  an  old saying that a sound mind requires a sound
body; yet, though parents are continually repeating it, and ap-
plying it to  the children of their neighbors, they rarely apply
it to  their OAvn, but endeaA7or to drive them through school
into college  or business long before they are fitted physically
for the mental effort to Avhich they are subjected.  The  evil
consequences of such a forcing system are to be seen in every
direction.  Hoav many unfortunate children can every teacher
point  out within the limit of his own experience Avho have
been  utterly disheartened and discouraged, and have finally
formed an unconquerable distaste for every variety  of mental
pursuit,  because they  have been  forced to undertake tasks
Avhich they were too young and feeble to accomplish.
   Though a  certain amount of exercise is necessary to the well-
being of the system, and enables it to undertake mental labor
with greater satisfaction and better results, it may be readily
carried to excess, and produce the opposite effect; intense, long
continued muscular labor is incompatible with intellectual ad-
  Under what circumstances should driving and the passive motion of separate limbs be
employed?  What is the average amount of exercise required by a healthy adult? 
286        DEVELOPMENT OF THE OSSEOUS TISSUE.

vancement.  The laborer is too weary to  study; all his nerv-
ous force is expended on his muscles, and there is nothing left
to stimulate the intellect.
  The osseous system requires a liberal supply  of phosphates
of lime for its proper development and support; these must
necessarily be introduced in the food; but, as we advance in
civilization and in the social scale, it seems as if we endeavored
to render our bodies more and more liable to disease, by chang-
ing the character of the diet, and rendering it less able to sup-
ply the w^ants of the system.
  The greatest demand  for phosphates exists during infancy
and  childhood; they  should therefore be supplied most freely
at this period.  The mother or nurse should use bread made
from flour that retains a part of the covering of the grain;  and
Avhen the child is weaned, coarse brown bread is a far better ar-
ticle of diet than the fine  white bread, which contains but a
very small proportion of phosphates.
                      LECTURE LIV.
                       PROPHYLACTICS.
History of Jenner's Discovery of Vaccination.— Quarantine.—Fomites.—
  Conditions that favor the spread of Cholera and the Fevers.—Purifica-
  tion of Streets and Public Places.—Purification of Private and Tenement
  Houses.—Personal Prophylaxis.— Insanity. — Cancer.—Phthisis.—Ef-
  fects of Intermarriages.— Conclusion.
  The last division  of the  subject  of hygiene is the use  of
prophylactics, by which we mean the methods or drugs  em-
ployed to enable the system to avoid disease.  The best exam-
ple of such methods is vaccination, for which Ave are indebted
to Jenner, who noticed that the girls employed in milking on
dairy-farms contracted sores on their hands, derived from small
ulcers on the  teats  of the  cows, and were not attacked by
small-pox.   Suspecting that the vaccinia of the  cow-teat was
the agent that protected the milkmaids from* the small-pox, he
submitted his theory to the  test of experiment, and found that
it was correct.
  Since the introduction of Jenner's system of vaccination, the
  Are labor and mental activity compatible ?  What is the essential condition for the prop-
er nutrition  of the osseous system ?  At what period of life is the greatest supply of phos-
phates required ?  What variety of bread furnishes the largest amount of phosphates ? What
a.r9, prophylactics ?  What is the history of vaccination ? 
QUARANTINE AND FOMITES.
287
small-pox, which was before his time a  tenable plague, carry-
ing off Avhole communities in a  season, has now become so
modified that it is comparatively rare,  and scarcely ever ap-
pears among the nations that maintain a strict system of Arac-
cination.
  As an example of the employment of drugs as prophylactics,
Ave  may cite the use of quinine as a protection against the ma-
larial poisons of our Southern States.  During the past war it
Avas administered as a regular ration to the troops stationed in
districts in which the various types of intermittent and remit-
tent fevers prevailed, and was found to reduce greatly the pro-
portion of such fevers.
  One  of the most  important prophylactic measures is the
quarantine.   It is established by  all civilized communities for
their protection against various plagues, and is founded  upon
the fact that such diseases are conveyed either by persons suf-
fering from  them, or by contact with infected clothing, bedding,
or  other substances that have been in contact with the  body
of a person afflicted AArith a contagious disease.  Infected arti-
cles are called fomites, which term embraces every variety of
object, from the smallest piece of clothing to the largest  ships
and hospitals.
  When the fomites are small, consisting of clothing, bedding,
and such articles, the quarantine laws generally demand that
they shall be burned, while vessels and buildings are subjected
to a thorough system of purification by  fumigation, or the use
of solutions of chlorine.  Whatever opinions may be held re-
garding the conveyance of contagious diseases by fomites, the
experience of all maritime  nations has  shoAvn that the estab-
lishment of a strict quarantine is the  only protection that hu-
man ingenuity has  devised  against their advance; and though
it may not succeed in arresting them, it is more or less effective
in retarding them, and enabling families and communities to
perfect their arrangements for avoiding their influence.
  The fearful epidemic  scourges Avhich from time to time sweep
over  the  Avhole civilized  world may be  greatly modified in
their character  and reduced in intensity by the  adoption of
proper  hygienic means.  We have already seen how the dis-
covery of Jenner has lowered the mortality of small-pox; and
though we do not  possess any such specific protection as vac-
cination in the  case of typhoid or typhus  fever, yelloAv  fever,
  What effect has vaccination had on the spread of small-pox?  Give an  example of the
use of drugs as prophylactics.  What is the object of the quarantine ? What are fomites ? 
288
CHOLERA AND  FEARERS.
and cholera, we can, by paying ordinary attention to the hy-
gienic condition of our streets, houses, persons, and food, reduce
greatly the chances of being attacked by these diseases.
   The spread of the fevers and cholera is governed by three
conditions. the first is contact with effluvia emanating from the
persons of individuals or fomites; 2d, a favorable state of the
atmosphere ; and, 3d, a  favorable condition of the body of the
individual exposed to the action of poisonous emanations.
   Whatever opinions may  be  held  regarding the contagious
character of certain diseases, even the most ardent supporters
of the non-contagious theory do not  care to expose themselves
unnecessarily to the chances of contact either with the persons
or clothing of those who are diseased.  We all, therefore, rely
to a  certain extent on  the quarantine to protect us as far as
possible  from  the introduction of fomites Avhich may become
foci or points  of origin  of the disease in our great commercial
cities.
   When the disease has appeared, every one is liable at any
moment to come in contact with the poison either in the streets,
stores, or public conveyances; we should therefore insist upon
the careful cleaning  of  our  streets, and the removal of all of
fensive matter which may by its decomposition render the at-
mosphere impure, and consequently more favorable to the con
veyance and extension of the disease by reducing the tone and
resisting powder of our bodies.
  The cleansing and use of such disinfecting agents as the
chloride of lime in the streets is very  important, but it is equal-
ly important that the air of our houses should also be purified.
It is said that in many of the houses  in New York the servants
first light the fires and pump  the water out of the cellars:
though this may be an exaggeration, we all know that a damp
cellar is  the rule and  a dry one the exception.   In Lecture
L. Ave have seen that a damp condition of the atmosphere is
peculiarly favorable  to  the conveyance  of all volatile exhala-
tions, and also reduces the tone of the system; it is therefore
very important that the cellar of every house, whether private
or tenement, should be properly cleansed, dried, and ventilated
during the years when  the epidemic diseases  are raging, if at
no other time.
  In  the winter  season the furnace  will generally produce a
sufficient ventilation  of  the cellar, and prevent the foul air en-
tering the house; but in the spring and summer, Avhen cholera
commences to rage Avith the greatest violence, the furnace is 
PURIFICATION OF HOUSES.
289
then extinguished, and there is no ventilation of the cellar.  At
this time the danger Avhich impends may to a great extent be
avoided by placing a small stove in it, in Avhich a fire should
be kept burning  continually; by  opening a  communication
Avith one of the chimney-flues and the top of the cellar the ven-
tilation aauII be most complete, for the air Avhich passes down
the gratings will escape partly by such an  opening and partly
through the stove near the floor, securing a change  of the at-
mosphere in  all parts of the space.   If the cellar  is long it
Avould be well to place the stove at one extremity, and  pass
the pipe through the Avhole length  of the apartment, to secure
warmth and Aentilation in all its divisions.
  Having provided suitable ventilation, the seAverage should
be put in thorough repair, for in many houses the waste-pipes
leak, and are continually delivering fluids laden Avith  organic
matter into the  cellar, where they assist  in producing noxious
A^apors, Avhich are also continually arising from soil that has
been filled in in leveling the streets and lots, and Avhich is  com-
posed often of the worst kinds of rubbish.  In order to  destroy
as far as possible the vapors Avhich originate from these or oth-
er causes, it is best to scatter some disinfectant, as  the chloride
of lime, over the floor or pavement, to prevent their introduc-
tion into the atmosphere.
  Next in importance to the purification  of  the air of our
streets and houses is a proper attention to the condition of the
skin and the character of the food.  Every one should  wash
the whole surface of the body  every day, or at least twice a
week.   In these general applications soap should  not be used
more than once a week, for it is not desired to remove the oily
secretions too often, but merely wash off the salts  that are ex-
creted so freely  in the form of perspiration during the warm
weather.  It is not necessary that the body should be immersed
in water; a sponge-bath, or Avet  towel and a basin  of tepid Ava-
ter, will  answer the purpose  perfectly, since the  object  is to
keep the surface of the skin clean, and free from all  secretions
soluble in water.
  As regards the  clothing, many recommend  that  a flannel
bandage should be worn over the abdomen; but it is better to
extend the application all over the surface of the body, and
wear a light  flannel or merino shirt and drawers all the sum-
mer: these should be removed  at  night, and hung  up to be
dried  and aired.  When the weather is warm, or perspiration
has been very free on account of violent exercise or  other cause,
                             T 
290
DIET IN CHOLERA SEASONS.
the flannel  under-clothing should be  changed two or three
Jimes a Aveek; it Avould be better to change it every day, Avhen
circumstances permit.
  Cholera and typhoid fever are both attended by great dis-
turbance of the digestive apparatus, a severe diarrhoea being
generally one of the first symptoms that attracts the notice of
the sufferer; and there  is no doubt that the use of some indi-
gestible article of food, or exposure of the skin  to draughts
without suitable protection, is frequently the exciting cause of
an attack of cholera or fever, which might otherwise have been
avoided.   The  effect of sudden change in the temperature or
dew point of the  air we may avoid by the use of flannel, but
the avoidance of indigestible articles is only to be accomplished
by a careful personal observation of each individual regarding
the articles  of food Avhich agree or disagree with his  own di-
gestive system, and in which he may be guided by an  examin-
ation  of the lectures on food and the methods of cooking.
  In selecting the articles to be employed as food during the
prevalence of cholera, we may, as a general rule, assert that all
vegetables sold in the great cities are unsafe;  they are rarely
fresh, and the best have been generally plucked  or gathered
two or three days before they reach the table.  The  greatest
care should therefore be taken in the purchase and selection of
fruits and vegetables, and it  would perhaps be best to avoid
their use altogether, and adopt a bread and meat diet, to which
some  alcoholic stimulant, tea or coffee, is added.   Of the alco-
holic  stimulants, whisky and brandy are the best; the differ-
ent varieties  of beer  and ale  are all laxative in their  nature,
and are very apt  to undergo  fermentation in the  stomachs of
those  unaccustomed to them.  The use of Cayenne pepper is
highly recommended, and, if employed in small quantities, can
certainly do no harm, and may be productive of great good; it
should be employed as a condiment  with the meats.
  The last and most important of all the hygienic means is a
perfect freedom of the mind from all depressing influences, and
especially from fear.   By adopting and following the simple
rules laid down in the preceding paragraphs, we place  our sys-
tems in the  most favorable condition for  resisting the attack
of epidemic  diseases, and avoid the  causes Avhich tend to pro-
voke or excite their onslaught.  We may therefore rest assured
that our chances of escape are great; and when we reflect hoAV
small a percentage of the population falls under the epidemic,
it is not in reality as fearful as it at first  appears, and all may 
INSANITY.
291
rationally feel that a reasonable attention to the laAvs of hy-
giene aa ill insure comparative immunity from such diseases.
  In the division or class of prophylactics Ave may include the
study of the origin  of insanity, and the methods by Avhich it
may be avoided.   One of the most influential causes of the pro-
duction of insanity is the presence of the disease in one or both
of the parents.  Whenever it is known to exist, the unfortunate
should not marry; for, though the disease may not appear in
the child of such a person, it  is liable to break out at any time,
eATen in the third or fourth  generation, blighting the life not
only of the  sufferer, but of all Avith AA'hom he is related, since
they are forced to  the sudden realization of the aAvful fact that
they too may at any moment be struck down, and forced to
spend  the remainder  of their  hVes in an  asylum.   Society
therefore demands, as an act of humanity, and a protection of
its  OAvn integrity, that an insane person should not marry, so
that with his death the disease may die also.
  In some instances insanity appears or is directly produced
by  some intense mental excitement, as that attending great
grief or joy; but it is generally found that even in these cases
there is a lurking taint in the  family,  which has been called
forth by the sudden excitement.  The only cases in Avhich in-
sanity arises Avithout the existence of  some previous taint is
either after violent inflammation of the  brain, or Avhen the par-
ents have been  closely related.  Both the civil and  religious
law have exerted their power to prevent the latter custom ; and
society has so recognized intermarriage of the members of the
same family as  the chief origin of idiotcy and insanity, that
Avhen such  marriages  occur  they are universally condemned,
and the products regarded with suspicion, as being candidates
at any moment for the asylum.
  The effects of any great popular or national excitement may
ahvays be traced in  the asylums of a nation by the increase in
the proportion of insane persons, all great wars, religious dis-
cussions  or revivals invariably producing a  disastrous effect
on  those Avho are disposed, by hereditary taint, to this fearful
disease.  Communities in Avhich there is great activity of mind
present conditions favorable  to the development of the disease;
Ave consequently find that, on examining the census statistics, it
is comparatively rare  among the Southern slaves, AAmile it is
common in New England.
  Though Ave can not control the causes Avhich are the imme-
diate excitants of insanity, we can, to a certain extent, prevent 
292
PHTHISIS AND  CANCER.
its increase by a proper attention to the prevention of inter-
marriages between those Avho are  closely related, or who al-
ready possess traces of the disease.
  Phthisis and cancer are also peculiarly liable to transmission
from one generation to  another.  They may, of course, arise
spontaneously,but in the great majority of cases they are hered-
itary;  and so clearly is this fact recognized by physicians, that
almost the first question put to a person suffering from either
is, " Of what disease did your parents die ?"  In these cases, as
in that of insanity, society again demands that it shall be pro-
tected, and frowns upon all marriages in Avhich such a taint is
known to exist.
  Though the all-important subject of Hygiene deserves  a far
more extended consideration than it has received in this work,
and could of itself fill many volumes, we have given it all the
space that circumstances allowed,  and have  presented many
facts of general interest and importance.  If a close  examina-
tion of these should lead to the adoption of a  course of living
AAThich  may render the life of even a single individual more en-
durable or enjoyable, we shall feel that our  task  has accom-
plished its end. 
INDEX.
                    A.
Abdominal cavity, 8; glands, 46.
Aberration,  chromatic  and  spherical, 206,
  211.
Absorption, 62, 66, 201 ; in plants, 67.
Acetabulum, 20.
Adipose tissue, 216.
Age, influence on temperature of body, 134.
Air-cells, 119; change of, 265; foul, 257; sac
  of fish, 132.
Albumen, 52 ; in blood, 72; in urine, 153.
Alcoholic fluids, 252; produced in fermenta-
  tion, 54.
Ale, 252, 254.
Alexis St. Martin, 58.
Allotropic form, 134.
Alveolar process, 17.
Analysis of bone, 9.
Anatomy defined, 6.
Anchovy, 245.
Angle of femur, 22
Animal charcoal,  10;  heat, 131 ;  simplest
  form of, 4 ;  animals, slaughtering of, 238.
Antrum, 17.
Anus, 35, 44; artificial, 44.
Aorta, 80, 83.
Apparatus, digestive, 34;  lachrymal, 210;
  respiratory,  118;  urinary, 135.
Appendix vermiformis, 35,  44.
Arachnoid, 172.
Areolar tissue, 215.
Aristotle, experiment of, 181.
Artery, 76, 85.
   "   Aorta, 80, 83.
   "   Axillary, 87.
   "   Brachial, 87.
   "   Cardiac, 83.
   li   Carotid, 86.
   "   Coeliac Axis, 88.
   "   Digital, 90.
   "   Epigastric, 89.
   "   Femoral, 89.
   "   Hepatic, 88.
   "   Iliac,  89.
   1    Innominata, 83.
   '•   Interosseous, 87.
   "   Mammary, 87.
   "   Maxillary, 86.
   "   Occipital, 86.
   "   Palmar Arch, 87.
   -'   Phrenic, 88.
   "   Popliteal, 89.
Artery, Profunda, 89.
   "   Pubic, 89.
   "   Radial, 87.
   "   Renal, 88, 137.
   "   Spermatic, 88.
   "   Splenic, 88.
   "   Subclavian, 86, 87.
   "   Superior Mesenteric, 88.
   "   Tibial, 90.
   "   Ulnar, 87.
Articulata, nervous systems of, 169.
Artificial anus, 44.
Asparagus, 244.
Asses' milk, 52.
Asthma, 246.
Auditory canal, 189; nerve, 193,195
Audubon, experiment of, 185.
Auricles, 78.
Aqueous humor, 208; vapor, 265, 269, 270,

                    B.
Balance, construction of, 105.
Ball-room, cautions on leaving, 268
Bathing, 271.
Baths, 272.
Beans, 243.
Beaumont, Dr., experiments of, 58, 59.
Beef,  238.
Beer,  252.
Beets, 243.
Berzelius's analysis of bone, 9.
Bicuspids, 37.
Bile, 8, 47; action of, 57; coloring matter in
  faeces, 62; regurgitation  of, 60;  in urine,
  155.
Birds, digestive apparatus  of, 61,62;  sense
  of smell, 185; voice, 197.
Black Assize, 257; Hole, 257
Bladder, 135.
Bloater paste, 245.
Blonde, milk of, 52.
Blood, 7, 70; change in passing through liv-
  er,  47;  reaction of, 71;  in urine, 154.
Blood-vessels,  76,  82 ; of stomach, 41.
Blow, effect on tongue,  183.
Body, divisions of, 8; fluids of, 7; tissues of,
  7.
Boiling, 241;  influence on digestibility of
  food, 59.
Bone, 9;  boiling,  258 ;  function of, 7; devel-
  opment, 12;  divisions of, 12.
Bone, Astragalus, 23. 
294
INDEX.
Bone, Carpal, 22.
  "   Clavicle, 21.
  "   Coccyx, 20.
  "   Cranial, 15.
  "   Cuboid, 23.
   '   Cuneiform, 22;  of foot, 23.
  "   Ethmoid, 16.
   '   Extremities, lower, 22; upper, 21.
  "   Face, 17,  18.
  ';   Femur, 22.
  "   Fibula, 22.
  "   Frontal, 15.
  "   Hand, 22.
  ''   Humerus, 21.
  •'   Hyoid, 18.
  "   Ilium, 20.
  "   Innominatum, 20.
  "   Lachrymal, 18.
  "   Magnum, 22.
  "   Malar, 18.
  '•   Maxillary, 17.
  "   Nasal, 17.
  "   Occipital, 15.
  "   Os calcis, 23.
  "   Palate, 18.
  "   Parietal, 17.
  "   Patella, 23.
  "   Petrous, 10,193.
  ■'   Phalanges of foot, 22.
  <;   Pisiform, 22.
  "   Pubes, 20.
  "   Radius, 21.
  "   Ribs, 19.
  "   Sacrum, 20.
  "   Scaphoid, 22, 23.
  "   Scapula, 21.
  "   Sphenoid, 15.
  "   Sternum, 20.
  "   Tarsal, 23.
  "   Temporal, 16.
  "   Tibia, 22.
  "   Trunk, 18.
  "   Turbinated, 18.
  "   Ulna, 21.
  "   Unciform, 22.
  "   Vertebral, 18,
  "   Vomer, 18.
Bouquet, 253.
Brain, 171.
Brande Table, 253.
Brandy, 255.
Bread-making,  55 ;  varieties of, 56.
Broiling, 59, 241.
Bronchi, 119.
Bronchitis, 130.
Brunner's glands, 49.
Brunette, milk  of, 52.
Cabbage, 244.
Caecum, 35, 43;  of fowl, 61.
Calorifacient  food, 53.
Canaliculi of  bone, 11.
Cancer, 60, 100, 292.
Canines, 37.
Capillaries, 76, 77.
Capillary attraction, 63 ; bronchi, 119; tubes,
  motion in, 93;  continuous flow in, 64.
Carbo-hydrates, 54.
Carbolic acid, 262.
Carbon, action of light on compounds of, 204 ;
  oxidation of, 133.
Carbonic acid, 63; expired, 125 ; produced in
  fermentation, 54.
Carbureted hydrogen, 258.
Cardiac opening of stomach, 41.
Carnivora,  digestive canal of, 61;  eyes of,
  215;  as food, 237; sense of smell in, 184
  teeth of, 38.
Carolina potato, 244.
Carrots, 243.
Cartilage, bone deposited in, 12 ;  function of,
  7; in joints, 25.
Casein, 52.
Castration of animals, 239.
Cataract, 214.
Cauliflower, 244.
Caviare, 241.
Cavities of body, 8.
Celery, 244.
Cells, anatomy  of, 3, 4; of lung, 119, 120;
  of muscle, 26; nerve, 167; nucleated, 4;
  reproduction, 5.
Cellulose, 62.
Cerebellum, 171, 173: function of, 177.
Cerebro-spinal axis, 171.
Cerebrum, 171.
Cerements, 278.
Cervical vertebrae, 18.
Champagne, 252, 253.
Charcoal, 262 ; animal, 10.
Cheeks, 38.
Cheese,  234.
Chemical rays, 203.
Chewing tobacco, habit of, 256.
Chilblain, 268.
Chimpanzee skull, 229.
Chloride of lime, 262; soda, 262;  sodium,
  use in system, 56;  in urine, 153.
Chlorine, 258, 262.
Chocolate, 251.
Choke-damp, 258.
Cholera, 288.
Cholesterine, 47; on nerves, 168.
Choroid, 20".
Chyle, 8, 57;  corpuscles, 70 ;  in urine, 156.
Chyme, 7, 56.
Cider, 254.
Cinnamon, 246.
Circle of Willis, 86.
Circulation of blood, 91, 92.
Claret, 254.
Climate influence on blood, 71;  on  intellect,
  269 ;  on diet, 246.
Clot, 71, 74.
Clothing, 277,280.
Cloves, 246.
Coats of eyeball, 207;  intestine, 41; stom-
  ach, 40.
Cochlea, 192, 195. 
INDEX.
295
 Cockspur, 101.
 Coffee, 250.
 Cold-blooded animals, 132 ; effects of, 267.
 Colic, 42.
 Colon, 35, 44.
 Coloration, 202.
 Colostrum, 100.
 Coma, 139.
 Comets, retardation of, 199.
 Composition of blood, 71; milk, 52;  muscle,
   25.
 Condiments, 245.
 Conjunctiva, 210.
 Connective tissue, 215.
 Constipation, 247.
 Consumption, 131, 233, 266.
 Contagion, 288.
 Corn,  243.
 Corns, 101.
 Corpus luteum, 219.
 Corpuscles, 70, 74 ; colostra], 100.
 Corsets, 280.
 Cotton clothing, 277.
 Cows'  milk, 52.
 Cramming, 239.
 Cranial cavity, 8; nerves, 173.
 Cream, 234.
 Croup, 130.
 Crystalline humor, 209, 211.
 Cucumbers, 244.
 Curd, 234.
 Currents in ocean, 227.
 Curves of vertebrae, 19.
 Cuticle, function of, 179.
 Cutis vera, 100, 103.
 Cylindroid epithelium of villus, 69.
 Cystic duct, 34.

                    D.
 Dancing, 284.
 Davy's experiments, 211, 277.
 Death, 225.
 Deleau's experiments, 198.
 Diabetic urine, 156.
 Dialysis, 65.
 Diarrhoea, 52.
 Diet influence on  milk, 233;  age and occu-
   pation, 232.
 Diffusion, 122.
 Digestion, 56; in birds, 61; mechanical the-
   ory,  58.
 Digestive apparatus, 34 ; juices, 8.
 Digitals, 87.
 Dipping, 255.
 Discs,  74, 75.
 Diseases of bones, 12 ,- joints, 25; respiratory
   apparatus,  130.
 Disinfectants, 262.
 Distillation of water, 250.
 Diversity of origin, 228.
Divisions of  bones, 12; digestive  apparatus,
   35;  food, 51; intestines, 41, 43; Physiolo-
   gy, 6 ; temporal bone, 15.
Draper, II., experiments on spleen, 160.
Draper, J. W., divisions of Physiology, 6.
 Draper, J. W., theory of circulation, 92.
 Draughts, 259, 276.
 Dromedary, colon of, 61.
 Dryness, effects of, 264, 269.
 Duct of pancreas, 48; sublingual, 45; AYhar-
   ton's, 45; hepatic, 34.
 Ductus communis choledochus, 48.
 Duodenum, 34, 42 ; reaction in, 57.
 Dupuytren's experiments, 247.
 Dura mater, 172.
 Dyspepsia, 242.

                    E.
 Ear, 189; comparative anatomy, etc., 196;
   trumpet, 187.
 Eau sucree, 250.
 Egesta, 50.
 Eggs, cooking of, 239.
 Elbow-joint, 21.
 Electricity and allotropic  state, 134 ; and ca-
   pillary attraction, 64; effects on body, 2G9.
 Elephant, colon of, 61.
 Elephantiasis, 249.
 Embonpoint, 245.
 Embryo, 221.
 Emulsion, 57.
 Enamel, 36.
 Endocardium, 78.
 Endolymph, 191.
 Endosmometer, 65.
 Endosmosis, 66.
 Endosteum, 12.
 Epidemics, 287.
 Epidermis, 101.
 Epiglottis, 34, 118, 197.
 Epilepsy, 44.
 Epithelium, 179; in faeces, 62.
 Ergot, 243.
 Esquimaux, food of, 51.
 Ether, 199.
 Excretion, 99.
 Exercise, 282.
 Exosmosis, 66.
 Experiments on  perspiration, 104;  respira-
   tion,  125; urine, 141.
 Expiration, 121.
 Extractive, 99; blood, 72; urine, 138.
 Extremities, 8.
 European skull, 229.
 Eustachian tube,  194.
 Eye, 207.
 Eyelids and eyebrows, 211.

                    F.
 Facial angle, 229.
 Facies Hippocratica, 225.
 Faeces, 48, 50,  62, 63, 247.
 Fallopian tube, 219.
 Fang of tooth, 36.
 Fat in blopd, 72;  disappears in liver, 47.
 Females, 273.
Fencing, 284.
Ferment, 4G; of gastric juice, 48.
Fermentation,  54  ; test, 157;  of water, 249.
Fermented liquors, 252. 
296
INDEX.
  Fevers, 287.
  Fibre, muscular, 26.
  Fibrin, 52, 72.
  Filtration, 250.
  Fire-damp, 258; open, 259.
  Fish, 240.
  Fistula, 43.
  Flannel clothing, 278.
  Flour, analysis of, 55.
  Flowers, 217.
  Flues, 259.
  Fluids of body, 7.
  Fluoride of calcium, 36.
  Focus, 205.
  Foetus, 221.
  Follicles of stomach, 40, 48.
  Fomites, 287.
  Food, 49, 50, 51, 53; digestibility of, 59;  sin
    gular articles of, 236.
  Foot, bones of, 23.
  Force, diffusion of gases, 124 ;  ascending  sap,
    68.                                   K
  Fracture of bone, 12;  skull, 17.
  Frangipane, 234.
  Franz, case of, 181.
  Frog web, circulation in, 94.
  Frostbite, 268.
  Fruits, 244.
  Frying, influence on digestibility of food, 59.
 Function  of  kidney, 139; liver,  158; skin,
   181; spleen, 160;  water in body, 50.
 Fumet, 237.
 Furnaces, 260.

                     G.
 Gall-bladder, 47.
 Ganglion, 168 ; duty of, 176; registering, 176.
 Gangrene, 268.
 Gastrocnemius, 33.
 Gases from intestine, 63.
 Gastric juice, 48 ; action of, 56.
 Geographical position, influence on distribu-
   tion of plants and animals, 227; influence
   on mortality, 224.
 Gestation, 221.
 Gin, 255.
 Ginger, 246.
 Glands, abdominal, 40; axillary, 276; Brun-
   ner's, 49; buccal, 45;  ceruminous, 103;
   gastric, 88; Lieberkuhn's, 43, 49; mam-
   mary, 100; parotid, 45; salivary, 45;  se-
   baceous,  103; sublingual, 45;  submaxil-
   lary, 45;  sudoriparous, 103.
 Globulin, 74.
 Gluten, 52,55.
 Goitre, 249.
 Growth, rate of, 222.
 Gruel, 250.
 Gullet, 39.
 Gums, 35.
 Gustatory nerve, 183.

                    H.
Habit, 247.
Haematin, 74.
  Hair, 102.
  Hammond, 108.
  Harvey's theory of circulation, 91.
  Haversian canals, 11.
  Heart, 77;  sounds of, 81.
  Heat, 219; excess,  133; influence on  color,
    228; latent, 51; in spectrum, 203.
  Hedgehog, killing of, 238.
  Helicotrema, 192,195.
  Heller's test, 155.
  Hemispheres of brain, 172.
  Herbivora,  digestive canal, 61; eyes, 215;
    sense of smell, 184; teeth, 38.
  Herpes, 240.
  Histogenetic food, 53.
  Home-sickness, 267.
  Horseback riding, 284.
  Horseradish, 246.
  Houses, situation of, 264 ; disinfecting, 288.
  Human life, periods of, 222.
  Humidity, effects of, 264, 269, 270.
  Humors of eye, 208, 211.
  Hunter's Museum, 15,101.
  Hydra, 35, 218.
  Hydrocarbons, 53.
  Hydrochloric acid derived from salt, 48; ac-
   tion on food,  53.
  Hygrometric state of air, 269.
 Hygiene defined, 6;  divisions of, 231.

                     I.
 Ice-water, 248.
 Idiosyncracies, 246.
 Idiot brain, 166.
 Idiotcy, 227, 291.
 Ileo-caecal valve, 43.
 Ileum, 34, 43.
 Incisors, 37.
 Incus, 190.
 Indian corn, 243.
 Indigestion, 57, 60.
 Ingesta, 50.
 Ingestion of food, effects of, 115.
 Infant, bathing  of, 273; brain  of, 166;  diet
   of, 232;  newly-born, 222;  temperature of,
   134.
 Influential ganglion, 177.
 Insanity, 291.
 Insects, eyes of, 211;  voice of, 197.
 Insensible perspiration,  104.
 Inspiration, 121.
 Intellectual life,  223;  power and labor incom-
  patible, 285.
 Interference,  201.
 Intermarriage, effects of, 291.
 Interstitial death, 226.
 Intestinal juices, 49, 58.
 Intestine, divisions of, 43.
 Involuntary muscle cells, 26.
 Iris, 209, 211.
 Ischium, 20.

                    J.
Jaw, human, 38; of rat, 38.
Jejunum, 34, 42. 
INDEX.
297
 Jenner, 286.
 Joints, 23, elbow, 21; hip, 20; wrist, 22.
 Jumping, 283.

                     K.
 Kangaroo, stomach of, 61.
 Kidney, 135; secretion of, 109.
 Knackers, 263.

                     L.
 Labyrinth, 190.
 Lachrymal apparatus, 210,213.
 Lacieal, 68
 Lactic acid,  54;  action in stomach, 57.
 Lacunae of bone, 11.
 Lamina spiralis, 191, 195.
 Language, 196, 198.
 Larrey, Baron, 267.
 Larynx, 34,  118.
 Latent heat, 51.
 Leaping,' 283.
 Leek, 243.
 Legumens, 243.
 Lehman, 108.
 Lemons,  245.
 Lenses, 205, 211.
 Leprosy,  240.
 Lettuce, 244.
 Levers, classes of, 24.
 Lieberkuhn,  glands of, 43.
 Life, theories of, 1; conditions of maintenance
   of, 2.
 Ligament, objects of,  7.
 Light, properties of,  198; effects on  system,
   269 ; maximum intensity of, 203.
 Lime-water, 248.
 Linen, 277.
 Lips, 25.
 Liqueurs, 254.
 Liquors, 254.
 Liver, 46, 158.
 Lobes of brain, 173;  of liver, 47; of lung,
   120.
 Lobule, 119.
 Longsightedness, 213.
 Lumbar vertebrae, 18.
 Lunacy, 227.
 Lung of frog, 133;  of reptile, 132.
 Lungs, 119, 120, 121.
 Lymph, 8.
 Lymphatics, 74.

                   M.
 Macaroni, 242.
 Madeira, 254.
 Malaria, 262; conveyed by moist air, 270.
 Malleus, 190.
 Malmsey, 254.
Malpighian capsule, 136;  tuft, 139.
Malt liquors,  252.
Mastication, 56, 60.
Mastoid process, 15.
Maumini's test, 157.
Meals, times  of, 231.
Meats, poisoned, 239.
   Meatus externus, 16; internus, 193.
   Meatuses of nose, 184.
   Meconium, 100.
   Medicines, 104, 247;  administered to infants
     233.
   Medulla oblongata, 173.
   Melon, 244.
   Membranes of brain, 172; serous, 35.
   Menstruation, 219.
   Mercury in capillary  tubes, 64; preparations
     of, 37.
   Mesenteric  glands, 69,  74;  action, 70; dis-
     eases, 70.
   Metatarsus, 23.
   Miasma, 262.
   Milk, 52, 100, 233;  teeth, 37.
   Mitral valve, 80.
   Modiolus, 191.
   Molars, 37.
   Mollusca, nervous system of, 169.
   Moore's test, 156.
   Mortality of infants, 235; rate of, 224.
   Mortification, 243.
   Mucous membrane, 35, 42, 58.
   Mucus in urine, 158.
   Mummies, 278.
   Murexide test, 152.
   Murray's observations, 279.
  Muscles, Biceps, 30.
      "   Bipenniform, 29.
'.      "   Buccinator, 29.
      "   Deltoid, 30.
      "   Extremities, lower, 33; upper, 30.
      "   Eyes, 213.
          Glutei, 33.
      "   Head, 29.
      "   Iliac, 33.
      "   Intercostal, 87.
      "  Latissimus dorsi, 30.
      "   Masseter, 29.
      "   Microscopic composition, 26.
     "   Obliquus externus and internus, 30.
      "   Occipito-frontalis, 29.
      "  Orbicularis oris, 29, 35,  palpebra-
            rum, 29.
      "  Pectoralis major and minor, 30.
      "  Penniform, 29.
     "  Psoas, 33.
      "  Radiate, 29.
     "  Rectus abdominalis,  30; femoris, 33.
     "   Sartorius, 33.
     "  Sterno-cleido-mastoid, 30.
     "  Temporal, 29.
     "   Tensor tympani, 194.
     "   Tibialis anticus, 33.
     "   Transversalis, 30.
     "  Trapezius, 29, 30.
     "   Triceps, 30.
     "   Trunk; 30.
     "   Vastus externus and internus,  33.
  Muscular tissue, 25.
  Mushrooms, 244.
  Must, 253.
  Mustard, 246.
|  Mutton, 238. 
298
INDEX.
                    N.
Nails, 102.
Nasal cavity, 8.
National life, 230.
Negro skull, 229.
Nerves,  cranial, 173; spinal, 174;  of teeth,
  36; gustatory, 183;  pneumogastric, 41.
Nervous force, origin of, 166; tissue, 7.
Nervous system, 166; of molluscs, 169;  rela-
  tion to animal heat, 133.
Neuralgia, 36.
Newton's theory of light, 198.
Nitrogen, 63.
Nitrogenized food, 52.
Non-nitrogenized food, 52, 53.
Nostalgia, 267.
Nucleolus, 4.
Nucleus, 3.
Nurse, choice of, 233.
Nursing, 233.
Nuts, 243.
Nutmeg, 246.
Nutritive food, 53.

                    O.
Oatmeal, 243.
Occupation, 278;  influence on diet, 246.
Ocellus, 211.
Odors absorbed by clothing, 281.
CEsophagus,  39;  position, 34;  entrance to
  stomach, 40.
Oils, 53.
Onion,  243, 246.
Orang skull,  229.
Orbital cavity,  8.
Organs of nutrition, 7; secretion and excre-
  tion,  7.
Origin of race, theories of, 228.
Osseous tissue, 10; system, 286.
Ossicles, 190, 194.
Ostrich, digestive canal of, 62.
Os uteri, 219.
Otolith, 191, 196.
Oviparous animals, 218.
Ovipositor, 218.
Ovum,  219.
Oyster, 241.

                    P.
Paine's experiments, 131.
Palate, 17, 34,  39.
Palmar arch, 87.
Pancreas, 48.
Pancreatic fluid, 48 ; its action, 57 ; regurgi-
   tation of, 60.
 Papillae of skin, 102,180; tongue, 182.
 Parotid gland, 45.
Parsnip, 243.
Parturition,  221.
Pastry, 242.
 Peas, 243.
 Pellagra, 243.
 Pelvic cavity, 8.
 Pelvis, 20.
 Penetrating power of lens, 206.
Pepsin, 48.
Peptones, 56.
Pericardium, 77.
Perilymph, 191.
Periosteum, 12.
Peritoneum, 40.
Perry, 254.
Perspiration, 50, 104.
Pettenkofer's test, 155.
Peyer's plates, 43, 49.
Phalanges, 23.
Pharynx, 34, 39, 118.
Phosphate  of soda,  73;  lime, 36, 73;  in sys-
  tem, 56, 286 ;  in  urine, 152.
Phosphoreted hydrogen, 63.
Phosphorus in nervous system, 166
Phthisis, 131, 292.
Physical agents, influence  on animals and
  plants, 228.
Physiology defined, 6.
Pia mater, 178.
Pigment of eye, 209, 211, 212.
Pinna, 189, 193.
Pipes for water,  249.
Placenta, 221.
Plantar arch, 90.
Plants, absorption in, 67, action on air, 257;
  heat developed in, 131.
Plasma,  71.
Plates of Peyer, 43, 49.
Pleura, 121.
Pleurisy, 130.
Pneumonia, 130.
Poisoning by meats, 239.
Polenta, 243.
Pollen, 217; microscopic composition of, 3.
Polypes, 35.
Pontine  Marshes, 264, 265.
Port, 254.
Portal circulation in kidney, 138.
Potato, 243 ; cooking of, 244.
Pressure, application of, 180.
Prisms, 200, 205.
Prophylactics, 286.
Ptyaline, 46, 56.
Pubic arch, 20.
Puddings, 242.
Pulmonary blood-vessels,  82;  circulation, 95.
Pulmonic heart, 78.
Pulsations of heart, 79.
Purgatives, 247.
Pus in urine, 157.
Pyloric valve, 39, 41, 63.

                     Q.
Quarantine, 287.
Quickening, 221.
Quinine, 287.

                     R.
Radiata, nervous svstem of, 169.
Radish,  243.
Rain, 248.
Receptaculum chyli, 169.
Rectum, 35, 44. 
INDEX.                                  299
Registering ganglion, 176.
Reflection of light, 200; of sound, 187.
Refraction of light, 202.          %
Refrangibility of different colors, 202.
Reptiles used as food, 240.
Reproduction, 217.
Respiration, 118; stages of, 121.
Respiratory apparatus, hygiene of, 257;  of
  fish, 132; food, 53;  instrument, 126.
Retina, 208, 209.
Rheumatism, 25; of heart, 78.
Rice, 243.
Rickets, 10.
Roasting, 241;  influence of, on digestibility
  of food, 59.
Rodentia, teeth of, 38.
Roman baths, 271
Root of lung, 119.
Rowing, 283.
Rum, 255.
Ruminant, stomach of, 60.
Running, 284.
Russian baths, 274.
Rye, 242.

                    S.
Saccule, 191.
Sacks, 254.
Sailing, 284.
Saliva,  action of, 54,  assists  gastric juice,
  57 ; effect on taste, 183;  mixed, 46; sub-
  maxillary, 46.
Salivary glands, 45.
Salt,  245 ;  action on taste, 183; in blood, 73;
  decomposition of, 48.
Salts in urine, 138.
Sanctorio, 111.
Sap, 67, 70.
Scala vestibuli and tympani, 192.
Schneiderian membrane, 184.
Sclerotic, 207.
Scurvy, 236.
Sea-bathing, 275.
Season, effect on meats, 237.
Sebaceous glands, 103.
Secretion, 99 ; intestine, 49; of pancreas, 48.
Seeds, 217.
Seguin, 112.
Selecting power of membranes.  64.
Semen, 220.
Semicircular canals, 191, 196.
Semilunar bone, 22; valves, 80.
Senses,  179.
Serous membranes, 35, 40.
Serum,  71.
Sex, effect on blood, 71; on pubic arch, 20.
Shampooing, 274.
Shell-fish, 240.
Sherry,  254.
Shock in bathing, 272.
Shortsightedness, 214.
Shoulder-joint, 21.
Sigmoid flexure, 35, 44.
Silicate of lime, 36.
Silk clothing, 278.
 Sinuses of brain, 90.
 Skeleton, 9 ;  bones composing, 15.
 Skin, 100; diseases of, 240; hygiene of, 271.
 Skull, measurement of, 229.
 Sleep, 226.
 Sleighing, 268.
 Smell, 183.
 Smoking, 255.
 Snails, 241.
 Snuff, 255.
 Soap, bubble diffusion, 123; use of, 271.
 Soda derived from salt, 48;  water, 250, 252.
 Song, 197.
 Sound, properties of, 185.
 Soup, 241.
 Sources of heat of body, 133.
 Special senses, 7.
 Specific gravity, 150.
 Spectrum, 200, 201.
 Speech, 198.
 Spermatozoa, 220.
 Spheroidal epithelium, 99.
 Spices, 246.
 Spinach, 244.
 Spinal cord, 173.
 Spinous processes of vertebrae, 19.
 Spleen, 158.
 Spongioles, 67.
 Springs,  248; water, 272.
 Spurred rye, 243.
 Squamous process,  15.
 Squinting, 214.
 Stapes, 190.
 Starch, 55, 57, 62.
 Stark's experiments, 281.
 Steam coils, 260.
 Steno's duct, 45.
 Stomach, 34,  39;   absorption,  69; content,
  40;  kangaroo, 61;  ruminant, 60;  shape
  of, 40.
 Stomata, 67.
 Stoves, 260.
 Strabismus, 214.
 Striped muscle fibre, 26.
 Study, effect on urine, 167.
 Sturgeon, 241.
 Sublingual glands, 45 ; submaxillary, 45.
 Substantia ostoidea, 36.
 Sugar, 53, 243, 244; acted on by pancreatic
  juice, 57; fermentation, 54;  in liver, 47;
  milk, 52;  refining, 10;  ships,  263;  in
  urine,  156.
 Sulphates in urine,  152.
 Sulphureted hydrogen, 63, 258.
 Sulphuric acid, effect on blood,  71.
 Sutures, 23.
 Sympathetic system, 168, 169.
 Synovial sac, 24.
 Systemic heart, 78; blood-vessels, 83.

                   T.
Tables of circulation,  97;   examination  of
  urine, 159.
Taliacotian operations, 101.
Tanks for water, 249. 
300
INDEX.
Tannin, 254.
Tartar, 254.
Taste, 182.
Tea, 250.
Teeth, 36, 234;  cutting, 38; permanent, 37.
Temperature, appreciation of, 180;  influence
  on fermentation, 54; influence on man and
  animals, 134.
Tendon,  29.
Testes, 220.
Thirst, 247 ; relieved by baths, 50.
Thoracic cavity, 8, 120;  duct, 69.
Tissue,  muscular,  25;  white  fibrous, 24;
  building food, 53.
Tissues composing body, 7; joints, 23; ori-
  gin and composition of, 3; formation of, 6 ;
  reparation of, 226.
Toast-water, 250.
Tobacco, 255.
Tokay, 254.
Tomatoes, 244.
Tongue, 39, 182 ; position of, 34.
Tonsils, 39.
Tooth, 101.
Toothache, 36.
Touch, 179 ; location of, 182.
Trachea, 118.
Training, 256.
Travel, 283.
Trees, effect on houses, 264.
Transmission of light, 201;  of sound, 187.
Tricuspid valve, 79.
Trommer's test, 156.
Tuberculosis, 131.
Tuberosity, femur, 22; ischium, 20.
Tubuli uriniferi, 136.
Turkish bath, 175.
Turnip, 243.
Tympanic cavity and membrane, 189, 194.

                    U.
Unity of origin, 228.
Unstriped muscular fibre, 26.
Urea, 138; not the product of muscular  ac-
  tion, 141.
Ureters, 135.
Uric acid, 138, 151.
Urinary apparatus, 135.
Urine, 50, 138; mucus in, 15S.
Urinometer, 150.
Uterus, 219.
Utricle, 191.
Uvula, 39.
                    Y.
Valentin, 112.
Valves of heart, 79 ;  veins, 95.
Valvulae conniventes, 42.
Variations in temperature, 135.
Vegetable food, 242; simplest form of, 4.
Vegetative life, 223.
Veins, 76, 90, 91;  portal,  47, 91.
Ventilation, 258, 288.
Ventricles, 78.
Venturi, principle of, 93.
Vermicelli, 242.
Vertebral column, 19.
Vertebrates, nervous system of, 169.
Vestibule, 191.
Villus, 42, 68;  absorption, 69.
Vinegar, 245 ;  effect on tongue, 183.
Viscera, temperature of, 134.
Vitreous humor, 209.
Viviparous animals, 218.
Voice, 196.
Voluntary muscle cells, 26.
Vomiting, 42.

                    W.
Walking,  283.
Warming, methods of, 259.
Water, 247, 272; in blood, 72;  introduction
  by  baths, 50;  long  application of,  276;
  warm, use of, 60.
Waves, 186;  theory  of light,  199.
Weight of human being, 222, 223.
Wells, 248; water, temperature of, 272.
Welsh rarebit, 234.
Wetting tubes,  64.
Wharton's duct, 45.
Wheat, 37; flour, 242.
Whey, 234.
Whisky, 255.
AVhisper, 198.
White fibrous tissue,  24; swelling,  25.
Wilson on diet, 231.
Winds, 265;  action of, 227.
Wine-making, 55.
Wines, 253.
Womb, 219.
Woolen clothing, 278.
Wounds of chest, 19  ; joints, 25.

                    Z.
Zygoma, 17.
THE  END. 
 
 
 
 
 
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