MISSOURI STATE SERIES. 
First Lessons 
IN 
PHYSIOLOGY 
* 
FOR 
USE IN THE COMMON SCHOOLS. 
By C. L HOTZE, 
Author of “ First Lessons Physicsetc. 
REVISED AND ENLARGED. 
** ST. LOUIS: 
American School Book Co Entered according to Act of Congress, in the year 1897, by 
W. B. BECKTOLI) 
In the Office of the Librarian of Congress, at Washington, D. C. PREFACE. 
The propriety of teaching some of the sciences in 
our common schools is so well esta1 ' shed as to require 
no further arguments. Nor does it seem necessary 
here to justify the claims of physiological science; 
educators, and the people generally, are agreed that 
a knowledge of “ the machine which we run and which 
© 
runs us ” is of the utmost importance. The question 
now under discussion is, how much of Physiology can 
be taught in the upper grades of the common 
without infringing upon the other studies? 
To facilitate the solution of this problem, as well 
as to meet the wishes expressed on many sides to see 
the essentials of Elementary Physiology arranged 
after the manner of the author’s “ First Lessons in 
Physics,” the present volume has been prepared. It 
comprises thirty-nine lessons on the structure and 
functions of the human body, the subject-matter being 
treated with reference to the wants of the young 
people in the classes alluded to. PREFACE. 
These lessons profess to present the amount of 
physiological science which should be taught in the 
common schools. They include the essentials of 
hygiene, which are treated in immediate connection 
with the function of the organ to which they refer. 
Many technical terms, and all “rules” of hygiene 
based on mere assumption or personal bias, together 
with a host of trivialities frequently met with in 
works of the kind, have been excluded. For while 
the teacher under favorable circumstances can easily 
go beyond the limits of the text, it is an objectionable 
feature in a school book if, after its purchase, pupils 
are obliged to skim, or omit, any part of it. 
Portions of recently slain animals should be used 
for demonstration, and the young learner be constantly 
urged to observe for himself. 
The present revised edition contains a new chap- 
ter— Lesson XL. — on Alcohol and its effects, Stim- 
ulants, Narcotics, etc., etc., which sufficiently meets 
the requirements recently made by several States 
of the Union to teach those topics in the common 
schools. In this Lesson, as well as throughout 
the work, the author has deemed it best to keep his 
text within the limits of understanding of the young 
people for whom the book is intended. CONTENTS. 
LESSON I. pagk. 
Organic and Inorganic Matter.—Animal Structure 9 
LESSON II. 
The Skeleton 13 
LESSON III. 
The Head.—Cerebro-Spinal Axis.—Teeth 17 
LESSON IV. 
Review 22 
LESSON V. 
The Trunk 24 
LESSON VI. 
The Limbs.—Ligaments 27 
LESSON VII. 
Cartilages.—The Larynx 30 
LESSON VIII. 
Review 33 
LESSON IX. 
Muscles.—Fat 35 
LESSON X. 
Muscles as Motor Agents.—Walking 38 
LESSON XI. 
Muscles, continued.—Work of Muscles 42 
LESSON XII. 
Review 48 
LESSON XIII. 
The Skin.—Hair and Nails.—Excretion of Skin 51 
LESSON XIV. 
The Blood 54 
LESSON XV. 
Circulation of Blood 1 58 
LESSON XVI. 
Circulation of Blood II 62 
LESSON XVII. 
Review 69 
LESSON XVIII. 
The Lungs 74 
LESSON XIX. 
Respiration 79 6 
CONTENTS. 
LESSON XX. page. 
Review 84 
LESSON XXI. 
Air and its Relation to the Human Body. 1 87 
LESSON XXII. 
Air and its Relation to the Human Body. II 92 
LESSON XXIII. 
Review 9^ 
LESSON XXIV. 
Food 101 
LESSON XXV. 
Digestion. I 106 
LESSON XXVI. 
Digestion. II. (Stomach) —... no 
LESSON XXVII. 
Digestion. Ill (Intestines) 113 
LESSON XXVIII. 
Assimilation 119 
LESSON XXIX. 
Review — 126 
LESSON XXX. 
Nervous System. I. Different Parts 130 
LESSON XXXI. 
Nervous System. II. Functions of Different Parts 137 
LESSON XXXII. 
Review 142 
LESSON XXXIII. 
The Senses in General.—Sense of Touch 144 
LESSON XXXIV. 
Taste and Smell 148 
LESSON XXXV. 
Sight. I - 15° 
LESSON XXXVI. 
Sight. II 154 
LFSSON XXXVII. 
Hearing....... 159 
LESSON XXXVIII. 
Review 163 
LESSON XXXIX. 
The Mind 166 
LESSON XL. 
Alcohol— Stimulant - Narcotics 172 
Questions r73 
Glossary of Words 
Index *9^ PHYSIOLOGY. 4» „tfeSSO% Vx 
jhf'SWu* in Q 
LESSON I. 
ORGANIC AND INORGANIC MATTER—ANIMAL STRUC- 
TURE. 
From time immemorial all tilings around ns have 
been looked upon as either living or lifeless. Liv- 
ing objects are plants and animals;—lifeless, such 
substances as mineral-coal, iron, sand, rocks, water 
or air. Although in the present advanced state of 
science it is often difficult to draw the line, yet that 
distinction is still maintained, because between 10 
FIRST LESSONS IN PHYSIOLOGY. 
things like those last mentioned, and substances such 
as wood or flesh, the differences are very striking. 
All so-called lifeless substances are comprised un- 
der the head of inorganic matter, while the vegeta- 
ble and animal worlds form the organic matter. 
The distinction between these two great classes of 
materials is based upon form, coherence, growth, 
composition and derivation. 
Form.—The sharp angles and straight lines of a 
crystal, the nearly regular features of most frag- 
ments of rock, are characteristic. On the other 
hand, notice the general absence of straight outlines 
in living structures, the curved shape of leaves and 
flowers, the rounded forms of the higher animals, 
and particularly those of the human body. Distin- 
guish between the fracture of a lump of mineral-coal 
and that of charcoal. It will be your impression that 
inorganic matter, generally speaking, assumes forms 
of a severer pattern. 
Coherence.—Particles of sandstone cling together 
owing to cohesion, without having any other mutual 
relation. A fragment of sandstone truly represents 
the original rock of which it once formed a part, in- 
asmuch as it possesses all the properties of the rock. 
The particles of a tree cohere likewise, but they are 
closely dependent upon one another. A piece of 
wood does not strictly represent the tree from which 
it came, because in different parts of the same tree 
the wood may have different properties. Hence, the 
coherence of organized matter greatly differs from 
that of substances of the inorganic world. ORGANIC AND INORGANIC MATTER. 
11 
Growth.— If the growth of a crystal, or of an or- 
dinary rock, could be plainly observed, it would be 
found to consist in a mere adding of particle after 
particle on the outside, without any interior devel- 
opment. Nor would it be found accompanied by 
decay, or repair, going on at the same time; whereas, 
plants and animals, during their growth, always 
decay in part—that is, while they are building up 
they also lose waste matter, only the building up is 
far greater in quantity than the waste. This is true, 
regardless of the manner in which a plant grows, 
whether, for example, like most of our trees, it grows 
by adding superficial layers or rings around the 
.stem, or, like Indian corn, by developing from 
within. Animals grow by interior development. 
'Carbonic acid gas and water-vapor are two products 
•of animal waste. Plants and animals make up the 
'Organic world, or world of organisms, and all organ- 
isms differ in their manner of growth from objects 
belonging to the inorganic world. 
Inorganic substances present a mere building up 
without corresponding development of all parts; 
while an organism develops throughout, and thereby 
attains gradually to a higher organization. The 
grain of corn generates the plant; the egg brings 
forth the bird; the infant develops into the full grown 
man. Nothing of the kind takes place in inorganic 
matter. 
Composition.—Copper, gold and iron are exam- 
ples of elemental bodies ; on being subdivided re- 
peatedly, each yields its like again. Water is an 12 
FIRST LESSONS IN PHYSIOLOGY. 
example of a compound body; it is composed of, 
and may be resolved into, two elements: hydrogen 
and oxygen. Clay, another compound body, con- 
sists of three or four elements. All these substances 
are inorganic; and nearly all inorganic substances 
are less complex in composition than organic bodies, 
such as wood or flesh. They are also more stable; 
that is, they do not decompose so readily. 
Derivation.—An organism is derived from a pa- 
rent ; inorganic matter is not. This is one of the most 
peculiar characteristics of organisms. 
Organisms live, develop and die; inorganic bodies 
are not said to live, develop, or die. 
The structure of a higher animal, required for 
the complete display of its capacities, may be repre- 
sented thus: 
1. An apparatus to convert food into a fluid which 
will develop and maintain the body, and to remove 
waste materials. 
2. A system of vessels to convey this fluid to all 
parts of the body. 
3. A muscle or heart, which, by contracting and 
relaxing, pumps the fluid into the vessels. 
4. A mechanism for respiration, so as to purify 
the fluid by a fresh supply of oxygen. 
5. Contractile cords or muscles to set the different 
parts of the body in motion. 
6. A mass of nervous matter, with nervous fibres 
spreading over the body, to receive impressions from 
the outer world, and to convey manifestations of 
will, &c., to the various portions of the body. BONES. 
13 
LESSON II. 
BONES — THE SKELETON. 
1. Experiment.—Expose a bone to the action of 
intense heat. Its shape will be preserved, but it 
will no longer be strong and tough; it will not sup- 
port as much weight as before. It has now lost its 
animal substance. 
2. Experiment.— Soak a bone in dilute acid. Its 
shape will be retained, but its firmness is destroyed; 
it may now be bent without breaking. It has lost 
its mineral substance. 
The composition of bones is a close union of ani- 
mal and mineral substances. In the normal bone 
both substances exist in definite proportions. A 
deficiency in the mineral ingredients (chiefly lime), 
as is the case with bones in early life, causes the 
bones readily to bend; while an excess of lime, 
always found in the bones of old people, renders 
the bones brittle. 
The structure of bones shows a net-work of small 
canals and layers of bone substance. Bones are less 
dense at their centers; many of them contain a fatty 
substance, called the marrow. Bones grow and con- 
stantly renew their particles. 14 
FIRST LESSONS IN PHYSIOLOGY. 
The growth of bones.— Every bone of an adult was 
at one time a cartilage. It did not become hardened 
uniformly throughout its mass, but the process of 
ossification—that is, the deposition of mineral mat- 
ter in the cartilage—took place first at particular 
points, called the centers of ossification. Thus the 
long bones of an infant contain at least three such 
centers or bony masses, one in the middle part of 
the bone (then as yet a cartilage), and one situated 
toward each end. In the adult these three osseous 
centers are united into one solid bone. 
When the edges or ends of bones in their growth 
come to touch each other, they either form joints or 
articulations, in order to enjoy motion upon each 
other; or they grow firmly together, forming sutures. 
Sutures may be readily ascertained in the bones 
composing the skull. 
The skeleton consists of all the bones in the hu- 
man body, the total number of which is about two 
hundred and ten, excluding the teeth. Besides, 
there is found a firm, elastic tissue called cartilage 
or gristle, such as the outer ear or the lower part of 
the nose. 
The skeleton forms the framework of the body. 
It is usually divided into three distinct portions : the 
head, the trunk, and the (upper and lower) limbs 
(Fig. 1). It contains three cavities; the uppermost 
is a hollow box of bone, the skull or cranium; this 
contains the brain, and has attached to it the jaws 
and the remaining bones of the head. Frontal Bone - - 
Upper Jaw 
Lower Jaw 
Collar Bone 
Chest ' 
or Thorax. ' 
... Occipital Bone 
Vertebrae of 
the Neck. 
• - - Vertebral 
Column. 
- - Shoulder Blade 
- - Upper Arm. 
- - Lower Arih. 
- Pelvis. 
_. Wrist. 
Palm. 
> - Fingers. 
Lower Arm. 
Upper Leg. 
Knee-pan 
Lower Leg. 
Tarsus, or Instep. 
Metatarsus. 
Metatarsus.. 
Toes. 
Fig. 1.—Thk Skeleton 16 
FIRST LESSONS IN PHYSIOLOGY. 
Below this a bony case or basket is seen, called 
the chest or thorax; and further down a bony basin, 
the pelvis. The chest and the pelvis, together with 
the backbone, form the trunk of the body. The 
arms, or upper extremities, are attached to the up- 
per part of the chest by means of the collar-bone 
and the shoulder-blade. The legs, or lower extremi- 
ties, are fastened to the lower part of the trunk. 
Bones, like all organic structures, consist of cells, 
that is, of cellular tissue ; the cells are more or less 
of a hexagonal form. Bones are renewed even more 
rapidly than any other portion of the body except 
the nails, the skin and the hair. The natural pro- 
cess by which broken bones are restored is remark- 
able. The immediate result of the injury is an 
effusion of blood around the broken parts. This is 
soon replaced by a watery fluid, after some 
time, thickens into a jelly-like mass. In a month or 
two this mass hardens, and slowly acquires the 
properties of bone; months after this the bones, if 
carefully treated, unite perfectly. THE HEAD. 
17 
LESSON III. 
THE HEAD—THE CEREBRO-SPINAL AXIS—THE TEETH. 
The head (Fig. 2) consists of the bones of the 
skull, face and ear. Its principal parts are : 
FIG. 2. 
1. The frontal bone. 
2. Two side bones, which form the uppermost part, 
and part of the right and left sides of the skull. 
3. Two temporal bones, one on each side of the 
lower part of the frontal hone. 18 
FIRST LESSONS IN PHYSIOLOGY. 
4. The occipital bone, extending down the neck. 
5. The upper jaw. 6. Two cheek bones. 7. Nose bone. 
8. The lower jaw, easily separable from the re- 
maining parts of the head. 
9. The sphenoid bone, forming the base of the skull 
(not visible in Fig. 2). 
The upper jaw contains the upper row of teeth, 
the lower jaw, the lower. The lower portion of the 
nose consists of cartilage, which remains soft during 
life. The roof of the mouth is a thin but hard bone, 
forming part of the upper j aw. 
The various bones of the head are firmly joined 
together, although they contain fissures and holes. 
According to the preceding lesson, the skeleton is 
composed of head, trunk and limbs ; and the trunk 
separable into chest or thorax, and pelvis. The 
young student will do well to observe that the head 
contains two distinct cavities : the cavity of the skull 
and that of the face, which are entirely separated 
from each other. The former contains a mass of 
nervous substance which is called the brain. This 
substance is continued down to the lower end of 
the pelvis, in the shape of a downward tapering cord, 
called the spinal cord. This cord together with the 
brain, pass under the name of cerebrospinal axis. 
Thus, we discover that the skull together with the 
vertebral column (Fig. 8), form a tube very much 
expanded above and exceedingly narrow at its lower 
end ; and that this tube is completely insulated, in 
the first place, by the bones of the skull, and sec- 
ondly, by the vertebral bones, or vertebrce. cp:rebro-spinal axis. 
19 
The other cavity, 
that of the face, con- 
tains the mouth. The 
mouth is part of an- 
other tube, called the 
alimentary canal, 
which extends from 
the mouth through 
the entire length of 
the trunk in front of 
the vertebral column 
(Fig. 3). The cavity 
of the mouth may be 
considered the ex- 
panded upper end of 
the alimentary canal, 
just as the cavity of 
the skull forms the 
upper expanded end 
of the tube containing 
the spinal cord. 
The cavity of the 
mouth contains two 
rows of teeth, one in 
tne upper jaw, me otner in me lower. Each tooth 
has a crown, neck and fany or fangs. The crown 
is the portion which projects beyond the gum. The 
neck is that portion immediately below the crown 
and on a level with the edges of the gum. The fang, 
or fangs if there be more than one, comprises all be- 
low the neck (Fig. 4). 
-Fig. 3 
VERTICAL SECTION OF THE HUMAN 
BODY. 
A. L.—Alimentary canal. 
V. C.— Vertical column. 
C. S.— Cerebrospinal axis. 20 
FIRST LESSONS IN PHYSIOLOGY. 
The crown is covered with an exceedingly hard 
substance, called enamel; this is the hardest por- 
tion of a tooth, and the hardest substance in the 
human body. It forms a very thin layer, and 
serves as a protection to the principal constituent of 
all teeth, the dentine or ivory. This dentine is hol- 
lowed out into a cavity, which contains a very sen- 
sitive mass of nervous matter, the tooth-pulp (Fig. 
4, a). Teeth are partially composed of bony mat- 
ter; they differ from bones in possessing enamel 
and dentine, which bones have not. Teeth have no 
growth. 
a b c d e / 
There are thirty-two teeth in number, sixteen in 
each jaw. The four front teeth in each jaw are 
adapted for cutting purposes, and therefore named 
incisors (b). On each side of them is a tooth with 
one cusp—that is, with a pointed crown (c). It is 
called the eye-tooth, or, because it resembles the long, 
tearing tusk of the dog, the canine. Next on either 
side is a tooth (d) with two cusps on the crown, lar- 
ger than the preceding teeth, and called bicuspid. 
Adjacent to it are teeth with more than two cusps, 
FIG. 4. TEETH. 
21 
the molars or grinders (e and/), the broadest and 
most powerful of all. The crowns of the molars in 
the lower jaw have four or five cusps, while those 
in the upper have one cusp less. 
In the early period of life, each jaw has ten tem- 
porary or milk teeth. At the age of six or eight 
the upper portions of these teeth fall out, or are 
‘shed,’ while the fangs are absorbed. Then appears 
the second or permanent set of teeth, thirty-two in 
number. The following formula shows that the 
molars of the child are replaced by the bicuspids 
of the adult: 
Formula of Arrangement and number of Teeth. 
Mo Ca In Ca Mo 
Upper, 2 1 4 1 2 = 10 
Lower, 2 1 4 1 2 = 10 
Temporary 
Teeth. 
=20 
Mo Bi Ca In Ca Bi Mo 
Upper, 3 2 1 4 1 2 3=16 
Lower, 3 2 1 4 1 2 3=16 
Permanent 
Teeth. 
=32 
Familiar Facts. — Sudden changes of tempera- 
ture, owing to very cold or very hot food or drink, 
are dangerous to the teeth, as they may cause the 
enamel to crack. Acids and metal toothpicks should 
be avoided. Teeth require cleansing with water and 
a soft brush, especially after meals. Any injury to 
the enamel is irreparable, and, as it causes the den- 
tine beneath to decay, may involve the loss of the 
tooth. 
(Compare Lesson XXV.) 
Bead “Toothacheby S. Parsons Shaw. Lippincott, Philadelphia. 22 
FIKST LESSORS IN PHYSIOLOGY. 
LESSON IV.—REVIEW. 
Lesson i.— 
1. Inorganic matter differs from organic, mainly 
in form, coherence, growth, composition and deriva- 
tion. 
2. An organism is an organized structure belong- 
ing either to the vegetable or animal kingdom. 
3. Only organisms live, develop and die. The hu- 
man body is the most perfect organism known. 
4. The structure of a higher animal required for 
the complete display of its capacities may be repre- 
sented thus: 1. An apparatus to convert food into 
a fluid which will develop and maintain the body, 
and to remove waste materials. 2. A system of ves- 
sels to convey this fluid to all parts of the body. 
3. A muscle or heart, which, by contracting and 
relaxing, pumps the fluid into the vessels. 4. A 
mechanism for respiration, so as to purify the fluid 
by a fresh supply of oxygen. 5. Contractile cords 
or muscles, to set the different parts of the body in 
motion. 6. A mass of nervous matter, with nerv- 
ous fibres spreading over the body, to receive im- 
pressions from the outer world, and to convey mani- 
festations of will, &c., to the various parts of the 
body. REVIEW. 
23 
Lesson ii.— 
5. Bones consist of animal and mineral material. 
The former renders them tough and elastic ; the lat- 
ter gives them strength. 
6. The animal substance in bones may be removed 
by heat; the mineral, by the action of acids. 
7. Bones grow and constantly renew their particles. 
8. The number of bones in the human body is 
about two hundred and ten. 
9. Cartilages are firm, elastic tissues. 
10. The skeleton may be divided into head, trunk 
and limbs. 
11. Bones, like all organic structures, consist of 
cellular tissue. 
Lesson iii.— 
12. The head consists of the bones of the skull 
and those of the face and ear. 
18. The principal parts of the head are: 1. The 
frontal bone. 2. The side bones. 3. The occipital 
bone. 4. The temporal bones. 5. The upper jaw. 
6. The cheek bones. 7. The nose bone. 8. The 
lower jaw. 9. The sphenoid bone. 
14. The cerebro-spinal axis comprises the spinal 
cord and the brain. 
15. A tooth is composed of a crown, a neck and 
one or more fangs. 
16. The tooth-pulp is enclosed by dentine; the 
dentine is capped by the enamel. 
17. The number of milk-teeth is twenty. 
18. Each jaw of an adult should contain sixteen 
teeth: four incisors, two canines, four bicuspids and 
six molars. 24 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON V. 
THE TRUNK. 
3. Experiment.—The carcass of a quadruped, 
if placed in a wooden box punctured on all sides, 
and buried in the ground close by an ant-hill, will 
after a few weeks be reduced to a skeleton, which 
may be used to advantage in studying the human 
skeleton. 
The skull is supported by an upright column, 
called the spinal column or back-bone. It consists of 
twenty-four separate vertebrae, which are so fastened 
together that the entire number appears as an un- 
broken pillar, forming the central, most important, 
and, let us add, the most wonderful part of the skel- 
eton. Nearly all the organs of the body seem to 
rely upon it for their support. It helps to form the 
back wall of the chest and abdomen, which are 
maintained by the pelvis or haunch bone. 
The vertebral and joints of the back-bone may be 
ascertained by the touch ; they begin with the back 
part of the neck and pass down to the pelvis. In a 
similar manner locate the ribs, which extend from 
the right and left of each vertebra in the thorax and 
encircle the chest. They are fastened in front to the 
breast bone or sternum. Find the two collar bones or 
clavicles, and observe their form. Next examine the VERTEBRAE. 
25 
two shoulder-blades; together with the clavicles 
they form the shoulder, and protect the lungs from 
above. 
The vertebral are perforated, that is, they contain 
a nearly oval cavity about an inch wide, filled with 
the spinal cord (Fig. 5, d). This cord extends down 
to the lower end of the pelvis. The spinal column 
protects the spinal cord within; it serves to bear the 
head aloft and to give the body its erect position. 
Fig. 5. 
A VERTEBRA. 
HORIZONTAL SECTION. 
TWO VERTEBRAE.—SIDE VIEW. 
Each vertebra presents the appearance of a hol- 
low cylinder, to the rear portion of which are at- 
tached seven superficial elongations or processes 
(Fig. 5, b and c). These processes are joined to ribs, 
ligaments (Lesson VI.) and muscles. 
The number of ribs fastened to the sternum is 
fourteen, seven on each side. The eighth and ninth 
ribs, on each side, do not reach far enough to the 
front; the tenth, eleventh and twelfth are shorter 
yet. These ten ribs are called the ‘ false ’ ribs. 26 
FIRST LESSONS IN PHYSIOLOGY. 
Between each pair of vertebrae is an interstice of 
about one-sixth the height of the body of the verte- 
bra. This space (Fig. 5, e) is occupied by two layers 
of cartilage, attached to the two bones. These car- 
tilages render the spine elastic, and make its joints 
yield and work with ease. (All of the bones named 
in this connection, except the body of each vertebra, 
are flattened and without cavity.) 
The pelvis supports the spinal column and the ab- 
domen. It is formed by the two hip-bones, which 
are held together by the lower part of the spinal 
column, the sacrum. 
During the day the spinal column, while in erect 
position, supports the weight of the head, arms, and 
nearly the entire trunk. This compresses the lay- 
ers of cartilage between each pair of vertebrae so as 
to diminish the length of the column. Hence, the 
human body is actually a little shorter toward even- 
ing, and resumes its normal length when lying in a 
horizontal position, or after a night’s rest. Elderly 
persons shrink in height, because their interverte- 
bral cartilages harden and become thinner; this 
accounts for their stooping posture. Persons in the 
habit of bending the head forward too far compress 
the front part of those cartilages, while the rear 
portion thickens. In course of time the cartilages 
lose their elasticity, and the spine becomes curved 
or ‘ crooked.’ The erect position of the spinal col- 
umn is one of the essential requirements of health. LIMBS. 
LESSON VI. 
THE LIMBS.—LIGAMENTS. 
Tty. 6 
Examine your arms, and locate 
their bones. You will find a long 
bone in the upper arm, and two 
long bones in the lower. So there 
is in the upper leg a long bone, the 
longest and strongest bone in the 
skeleton; and there are, also, two 
long bones in the lower leg. 
The hand (Fig. 6) is composed of 
three parts: the fingers, the palm 
and the wrist. The wrist contains 
eight little bones, placed in two 
rows ; together with the bones of the 
fore-arm, they form the wrist-joint. 
The palm has five bones. The four 
fingers have three bones each; the 
thumb contains only two. The 
entire hand, therefore, contains 
twenty-seven bones. 
The foot, in a similar manner, is 
composed of the toes, the metatar- 
sus, and the tarsus or instep. The 
great toe contains two bones; the 
remaining toes, like the fingers of 
the hand, have three bones each 
(Figure 1). The instep has seven 
8ones ofthe Arm and Hand. 28 
FIRST LESSONS IN PHYSIOLOGY. 
bones ; the metatarsus, five. In all, there are twenty- 
six bones in the foot. The heel supports the rear 
portion of the foot, or the whole body when the body 
is in erect position. 
The knee-jpan covers the forepart of the knee-joint. 
The mechanism which adapts the limbs in the 
human body to their manifold uses is remarkable 
for its effective plan and devices. No animal ex- 
hibits a system of joints which is movable in so 
many directions, and yet is so firm and stout. No 
animal possesses such gracefulness in the motions 
of its limbs, combined with so vast a capacity of 
exertion and endurance. 
The limbs are joined to the trunk in a manner 
such that they enjoy motion in every direction— 
upward, downward, forward, backward, and in a 
circular manner. This is secured by a ball-and- 
socket joint where the globular-shaped head of a 
bone plays in a cup or socket. The elbow and the 
ankle have each a hinge-joint, which allows forward 
and backward motion only. 
The foot does not rest upon its whole lower sur- 
face, but, having the form of an arch, it touches the 
ground only at the heel and at the ball of the toes 
in front. All the bones composing this arch, or 
“ hollow of the foot,” are fastened to each other by 
ligaments in such a manner as to give them a large 
amount of spring-force with which to resist the ef- 
fects of pressure produced by the weight of the body 
and by the jar against the ground. To convince one 
of the truth of this, he needs but place the hollow of 
the foot upon the round of a ladder. LIGAMENTS. 
29 
Ligaments.—The movable joints are fastened to- 
gether by ligaments. Ligaments are firm, fibrous 
bands with very little mobility. The bone to which 
a ligament is fastened may be broken by an acci- 
dent, without harm to the ligament itself. If our 
joints were formed by the direct contact of bones, 
these bones could scarcely play upon each other; 
hence, there is cartilaginous tissue between them, 
to give them a greater or less amount of play and 
elasticity. In the movable joints the surfaces which 
play upon each other are covered with cartilage. 
Moreover, they are enveloped by a sort of sac, which 
secretes a lubricating fluid resembling the white of 
an egg. 
Familiar facts.—Animals can not move their 
claws separately; man is able to move any of his 
fingers independently. No animal except the hat 
is competent, with his fingers, to make a span equal 
to the entire length of the hand. While many an 
animal has something like fingers; while the bird 
possesses a flying apparatus, and the horse greater 
capacity for running than man, man alone has so 
perfect a machine as the human hand with which to 
execute such complicated motions and to assume 
such manifold positions and forms. 
Read Dress and Care of the Feet. Sam. R. Wells, Publisher, 389 
Broadway, New York. 
Read The Hand, by Sir Charles Bell. Harper & Bros. 30 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON VII. 
CARTILAGES — LARYNX — TRACHEA. 
Examine, and compare with each other, the nasal 
cartilage, the external ear and the gullet of a bird. 
The first is an appendage to a bone, the second is 
not directly connected with any bone, the third is a 
structure entirely independent of bones. All three 
are illustrations of a dense, firm substance, called 
cartilage or gristle. It is nearly related to bone* 
but lacks the mineral ingredients of bone, and is,, 
therefore, softer and more elastic. 
The chief uses of cartilage are the following: 
(1.) To yield smooth surfaces for easy friction in 
the joints; and to act as a cushion in shocks. 
(2.) To fasten "bones together without destroying 
freedom of movement, as between the vertebrae. 
(3.) To serve as a firm yet not unyielding frame- 
work, as in the larynx and trachea. 
(4.) To adapt itself to all purposes where firm- 
ness, toughness, elasticity and strength are re- 
quired. 
The Larynx. — To the rear of the tongue is an 
aperture, the glottis, with a sort of fleshy cover, the 
epiglottis (Fig. 7). This aperture leads to a cavity, 
the larynx, whose sides are composed of cartilage. LARYNX. 
31 
The lower continuation of the larynx forms a long 
tube, the trachea or windpipe, composed of cartila- 
Epiglottis. 
Larynx. 
Trachea. 
Right Bronchus. 
.Left Bronchus. 
Fig. 7.—Lahynx and Tbachea. 
ginous rings, some of which may he felt from with- 32 
FIRST LESSONS IN PHYSIOLOGY. 
out. These rings are complete only in front; in the 
rear, where the trachea rests against the gullet, their 
ends are connected with each other by a thin mem- 
brane and by muscular fibres. 
The trachea, after entering the thorax, separates 
into two branches, the right and left bronchi. These 
enter the lungs and divide further into a great many 
smaller bronchial tubes. 
The larynx is the organ of the voice. It contains 
within its cartilages, immediately below the epiglot- 
tis, two elastic lips, known as the vocal chords. 
These chords are controlled by certain muscles, so 
that they can close the larynx against the passage 
of air to or from the lungs. They can also be re- 
laxed, or shortened and lengthened, so as to throw 
currents of air passing between them into vibra- 
tions— that is, so as to produce sound. During in- 
spiration the vocal chords are widely separated; 
during expiration they relax somewhat, and are 
nearer together. 
Questions : 
1. Why is not the spinal column made up of a 
single bone in place of the vertebra? ? 
2. Why are not all the ribs attached to the ster- 
num ? 
3. When has the human body greater length than 
usual ? 
4. State why this is the case. 
5. How does a bone differ from cartilage ? REVIEW. 
33 
LESSON VIII.— REVIEW. 
Lesson v.— 
1. The spinal column directly supports the skull; 
it is itself supported by the pelvis. 
2. The spinal column consists of twenty-four sep- 
arate bones or vertebrae. 
3. The trunk contains the spinal column ; twenty- 
four ribs, twelve on each side; the breast bone, two 
clavicles and the two shoulder-blades; two hip- 
bones and the sacrum. 
4. The spinal column protects the spinal cord 
within ; it serves to bear the head aloft, and to give 
the body its erect position. 
Lesson vi.— 
5. The arm is composed of a long bone in the up- 
per arm, two bones in the lower, and twenty-seven 
bones in the hand. 
6. The leg is composed of a long bone in its upper 
part, two bones in the lower, and twenty-six bones 
in the foot. 
7. The ball-and-socket joint permits motion in all 
directions; the hinge-joint, only in two. 
8. The arch of the foot renders the foot better ca- 
pable of supporting the weight of the body. 
9. The movable joints are fastened together by 
ligaments. Ligaments are firm, fibrous bands with 
very little mobility. The bone to which a ligament 
is fastened may be broken by an accident without 34 
FIRST LESSONS IN PHYSIOLOGY. 
harm to the ligament itself. If our joints were 
formed by the direct contact of bones these bones 
could scarcely play upon each other; hence, there 
is cartilaginous tissue between them, to give them 
a greater amount of play and elasticity. In the 
movable joints the surfaces which play upon each 
other are covered with cartilage. They are envel- 
oped by a sort of sac, which secretes a lubricating 
fluid resembling the white of an egg. 
Lesson vii.— 
10. The chief uses of cartilage are: 1. To yield 
smooth surfaces for easy friction in the joints, and 
to act as a cushion in shocks. 2. To fasten bones 
together without destroying freedom of movement, 
as between the vertebrae. 3. To serve as a firm yet 
not unyielding framework, as in the larynx and 
trachea. 4. To adapt itself to all purposes where 
firmness, toughness, elasticity and strength are re- 
quired. 
11. The larynx consists of a cavity surrounded by 
cartilages ; it is the organ of the voice. 
12. It contains the vocal chords, which produce 
sound by causing currents of air passing between 
them to vibrate. 
13. The trachea consists of cartilaginous rings, 
which are complete only in front. 
14. The right and left bronchi are two branches 
of the trachea; they divide into finer bronchial 
tubes. 
15. The epiglottis serves as a protection to the 
larynx. MUSCLES. 
35 
LESSON IX. 
MUSCLES — EAT. 
4. Experiment.— Stretch out one arm and let 
its upper part be grasped by another person. Then 
slowly bend up the fore-arm; the person will now 
feel that a portion of the upper arm is swelling; in 
fact, there is now a compact mass of flesh which 
was not observably so prominent before, and which 
relaxes again when the arm is stretched out. Could 
we remove the skin after the arm is bent up, we 
would find a mass of red flesh or muscle, called the 
biceps muscle. 
The motion of this muscle is, like all motion, the 
manifestation of a force; in the present case, the 
force of the will. The flesh or muscle is the carrier 
of this force. 
A muscle is an aggregation of minute fibres, each 
of which is again composed of minute fibrils, held 
together by a delicate membrane. All the motions 
in the animal body are performed by muscles. 
Muscles, generally speaking, are the organs of mo- 
tion. 
The above experiment shows that muscles pro- 
duce motion by means of their contractility. This 
is the first property of muscles. Contractility implies 
the power of shortening and lengthening, and it is 36 
FIRST LESSONS IN PHYSIOLOGY. 
in this way that muscles move the bones to which 
they are attached. The second property of muscles 
is their sensibility. As a general thing, healthy mus- 
cles are not very sensitive; witness the slight pain 
caused by a cut in the flesh. Their sensibility con- 
sists in this, that they can communicate to the mind 
the state and condition in which they are. If, for 
example, a muscle is fatigued, or in a state of cramp, 
we immediately become conscious of it. 
About ten minues after death the muscles of the 
body pass, spontaneously, into a state of contrac- 
tion very nearly like that which takes place during 
life. This produces a general stiffness of the entire 
body, and is known as the rigor mortis, or post-mor- 
tem rigidity. 
There are two kinds of muscles, distinguished by 
their structure and mode of action: first, the volun- 
tary muscles, as the biceps and nearly all the mus- 
cles used for moving bones. The action of volun- 
tary muscles is, to a large extent, controlled by the 
will. Second,, the involuntary muscles, as in the tra- 
chea, the bronchi and the digestive canal. These 
muscles are beyond the control of the will. Thus, 
whether we will or not, the process of respiration 
goes on day and night. The roughness of skin, 
called goose skin, is caused by the action of involun- 
tary muscular fibres in the skin. It is usually the 
result of cold, electricity, or sudden mental impres- 
sions. 
In children, and in some adults, we notice a soft 
tissue, called adipose tissue, or fat. It exists in FAT. 
37 
nearly all parts of the body. Its chief uses are the 
following: 
1st. The fat, which is situated directly beneath 
the skin, prevents much of the heat of the body 
from escaping, because fat is a bad conductor of 
heat or cold. 
2d. Fat serves as an elastic packing material to 
wrap delicate structures, such as the palm of the 
hand and soles of the feet. 
3d. It serves as a store of combustible matter— 
that is, it may be burnt up in the system, and thus 
become a source of heat to the body. 
4th. It serves to fill the cavities of the long hones. 
It is then called marrow. 
Read Woman’s Form. Harper’s Magazine, Vol. 37, July, 1868. 38 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON X. 
MUSCLES AS MOTOR AGENTS—WALKING. 
[First read Lesson XVI, “ The Lever,” in Ilotze’s First Lessons in 
Physics.] 
5. Experiment.—Straighten the arm and extend 
it horizontally ; place a five-pound weight on the 
hand. To uphold this weight a muscular effort, or 
force, of about 100 pounds is required, to say noth- 
ing of the effort to sustain the weight of the arm 
itself. 
Before investigating this phenomenon, the young 
student should he reminded that the human arm is 
a lever with its point of support, or fulcrum, at the 
point o (Fig. 8) in the shoulder-joint; and that, in 
virtue of this joint being a ball-and-socket joint 
(page 28), the arm enjoys motion in a variety of 
Fig-8 
directions; and that all these motions are exerted 
by strongly-developed muscles, extending from the 
shoulder-blade, clavicle and thorax to the upper 
arm, to which they are attached (pp. 43 and 45.) MUSCLES AS MOTOR AGENTS. 
39 
The weight (Fig. 8) is supported by a shoulder- 
muscle, through which the power is exerted at the 
point b. Joining the points o, b and a (the weight) 
by straight lines, a bent lever, ob a, with fulcrum at 
o, is formed. The weight evidently operates at the 
end of the long lever-arm, a b, while the muscular 
power at b operates only by the short lever-arm, o b. 
The ratio of the two lever-arms is about as 20 to 1. 
This explains why the live pound weight, at the end 
of the long arm, acts with a momentum of nearly 
5X20 = 100 pounds; and why the strong shoulder- 
muscle at the end of o b, in order to balance this mo- 
mentum, must pull upward with a force of (nearly) 
100X1 = 100 pounds. It also accounts for the fact, 
known to every one, that it requires exertion to hold 
the arm extended, even without any additional 
weight in the hand. 
The strong shoulder-muscle here mentioned is 
omitted in Fig. 8, because it would prevent o b from 
being seen. This muscle is the chief but not exclu- 
sive supporter of the weight of the ball and that of 
the extended horizontal arm; in this it is assisted by 
other muscles, among which is the biceps—the mus- 
cle visible in Fig. 8. 
The lever, o b <z, is a lever of the third class, the 
power being applied between the fulcrum and the 
weight. A pair of tongs with which to lift lumps of 
coal is also a lever of the third class. If, now, with 
a little imagination, we compare the point where 
the tongs are riveted together with the point below 
each ear where the jaws come together; and if, fur- 40 
FIRST LESSORS IN PHYSIOLOGY. 
tliermore, we imagine each half row of teeth to be a 
lever similar to one of the levers of the tongs, then 
half the upper jaw, with its lower half attached, 
forms a pair of levers like a pair of tongs. The far- 
ther to the rear the resistance to be overcome by 
the teeth be placed—that is, the nearer to the ful- 
crum—the shorter do we make the lever-arm at the 
end of which the weight or resistance operates, and 
the less muscular effort is required. It follows, then, 
that the jaws exert the greatest force between the 
hindmost molars. Toward the front part of the jaw 
the teeth lose their grinding power, and it is a wise 
provision of nature that the front teeth, having but 
small capacity otherwise, possess a knife-shaped 
form. 
From the preceding it would appear that a large 
amount of muscular force exerted by a human be- 
ing during the day is wasted; but we must remind 
ourselves that much of the force apparently lost is 
realized as a gain of time, a convenience of direction, 
and as a greater range of motion. 
It should be stated here that nearly all muscles 
terminate at their ends, where they are attached to 
bones, in sinewy, inelastic cords, called tendons. 
Tendons form the connecting link between muscle 
and bone, just as ligaments between bone and bone. 
The leg of a turkey furnishes an abundance of ten- 
dons. 
Standing.—When the centre of gravity of a body 
is supported, the entire body is supported. The 
centre of gravity in the human body lies in the ab- WALKING. 
41 
domen. In order that a person may stand erect, 
therefore, the centre of gravity must be supported 
by the legs. This requires work on the part of all 
the muscles below the trunk. The amount of this 
work is very great; this is proved—(1) by the diffi- 
culty which a little child experiences in learning to 
stand erect; (2) by the necessity which the adult ex- 
periences while standing, of frequently shifting the 
centre of gravity, throwing it alternately over one 
limb, so as to allow the other to rest for a short time. 
Walking.—This act comprises, 
(1) The lifting of the body. This is accomplished 
by lifting the leg; that is, by increasing the distance 
between the toes and the centre of gravity. During 
this action, the same leg supports the entire weight 
of the body; the other leg, having at the time no 
load to carry, swings freely forward, after the man- 
ner of a pendulum. 
(2) The forward motion of the body, and its sub- 
sequent downward motion as the foot of the other 
leg is planted on the ground. 
(3) The forward swinging of the leg. The other 
leg now bears the weight of the body, while the first 
leg swings freely forward. This mechanical for- 
ward swinging requires scarely any muscular exer- 
tion ; hence it affords alternate rest to each limb. 
Although the entire weight of the body is carried 
alternately by one foot, yet an hour’s walk is less 
fatiguing than to stand still for an hour, because, in 
walking, each limb enjoys alternate rest. 42 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XI. 
MUSCLES, CONTINUED—WORK OF MUSCLES—LEAPING. 
Muscles remain contracted only for a short period. 
They soon relax, and during relaxation their pre- 
vious strength is regained. In walking, the muscles 
are constantly changing from contraction to relaxa- 
tion, while the erect position of the body requires 
the activity of all the muscles ; for those muscles 
which are situated in front prevent the body from 
inclining backward, while those behind prevent the 
body from bending forward. The muscles upon the 
sides of the body act in a similar manner. This ex- 
plains why to stand erect and motionless for a given 
time is much more tiresome than to move about 
during an equal length of time. We gather new 
strength when we rest or sleep; complete rest is 
found only in a lying position. 
The muscles are wrapped in a tissue which is 
found in nearly all parts of the body; it envelopes 
the muscles, it coats the bones and cartilages, and 
thus connects the different portions of the human 
body with one another. According to its different 
uses, it varies greatly in character, being at times 
soft and tender, at other times very dense and 
strong, as, e. g. in the tendons. It is called connec- 
tive tissue. MUSCLES. 
43 
Fig. 9.—Muscles. 44 
FIRST LESSONS IN PHYSIOLOGY. 
The muscles of the head and trunk perform no 
such intense labor as those of the limbs ; hence, 
they are less substantial. The roof of the skull has 
no muscles proper, but a tendinous cap, or helmet, 
underlying the hairy skin; it may be moved by 
muscles in the front and rear portion of the head. 
The muscles of the eye are of a very delicate struc- 
ture, and so arranged as to roll the eye-ball, move 
it slightly forward and backward, and to raise and 
lower the eye-lids. The tongue, the interior of the 
mouth, the throat, in line, all the parts of the body, 
have suitable layers or strings of muscles in order 
to produce motion, to hold the limbs in position, and, 
in general, to protect the skeleton. The entire num- 
ber of external muscles may be set down at two 
hundred and forty pairs (Figs. 9 and 10). 
When a force performs work, the work is always 
a motion of some kind or other. The force of the 
will or mind, when imparted to a muscle, causes 
the muscle to perform work which, for the greater 
part, consists of motion. Motions produced by the 
human body are utilized mainly because of their 
being converted into force when they are suddenly 
arrested. The blacksmith, having imparted motion 
to his hammer by lifting it, changes this motion into 
force when the hammer strikes the iron upon the an- 
vil. If the weight of the hammer =3 pounds, and 
the height of its descent = 4 feet, the work performed 
by the person is 3x4=12 footpounds. (A footpound MUSCLES. 
45 
Fig. io.—Musci.ss. 46 
FIRST LESSONS IN PHYSIOLOGY. 
is a pound lifted through one foot of space against 
gravity.) But this does not tell us anything about 
the quantity of muscular exertion. Perhaps the 
following instance will make it clearer: . If an 
adult weighing 150 pounds wishes to leap two feet 
high, the amount of work=2Xl50=300 footpounds. 
On an inclined plane, or a stairway of gentle slope, 
this amount of work is performed easily in one or 
more seconds. But to do it by jumping seems to 
require a greater effort, although the amount of 
work performed remains the same. 
Leaping is a combination of two essentially dif- 
ferent motions : First, the body is lifted by the ac- 
tion of the muscles; of course, there must be a sup- 
port under foot. Next, the feet separate from the 
ground and the body rises; gravity stops its up- 
ward motion and pulls it down again. Let us re- 
call the above example. The first motion, viz., 
the lifting of the body, is effected by muscular ac- 
tion. It has a limited range, perhaps no more than 
one-half foot. Now the entire work, as we have 
seen, amounts to 300 footpounds, and is carried on 
by a muscular action through one-half foot of 
space. Therefore, the muscular action, that is, the 
entire pressure of the feet against the ground, 
while the body is moving upwards one-lialf foot, 
in order to produce 300 footpounds of work, must be 
equal, to 600 pounds, for In order that 
a person may be able to produce so great a pressure 
through the one-half foot of space, he must first 
assume a stooping position. It is the muscular ef- LEAPING. 
47 
fort required to produce this great pressure that 
makes the task so arduous. 
The Heart (page 58) is a muscle which, by it mo- 
tion, propels the blood through the body. At every 
contraction of the ventricles a charge of about six 
ounces of blood is driven into the arteries. The great 
velocity imparted to the blood, and the fact that 
during life the motions of the heart are carried on in 
never-ceasing successions—the heart, like the lungs, 
never rests while the vital processes are in function 
—render it, beyond doubt, that the heart incessantly 
performs an enormous amount of work. 
The experience of a long period of years has 
shown, beyond doubt, that the mechanical power of 
the human body is used to best advantage by both 
employer and employee when the work is done reg- 
ularly and continuously, not in separate, fitful exer- 
tions. Man’s forces must not be exhausted further 
than rest and food can replace them day by day. 
In utilizing our physical forces, therefore, certain 
limits must be observed, a limit of exertion as well 
as a limit of time. Any deviation has always been 
followed by a deterioration in the value of the 
work done. 
Read The Wonders of the Human Body. Illustrated Library of Won- 
ders. Scribner & Armstrong, New York. 48 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XII. —REVIEW. 
Lesson ix. 
1. A muscle is an aggregation of minute fibres, 
each of which is again composed of minute fibrils, 
held together by a delicate membrane. All the 
motions in the animal body are performed by mus- 
cles. Generally speaking, muscles are the organs 
of motion. 
2. Muscular motion is exerted by means of the 
contractility of muscles. 
3. Contractility and sensibility are characteristic 
properties of muscles. 
4. Contractility implies the power of contracting 
and relaxing; sensibility, their power of commun- 
icating impressions directly to the mind. 
5. Post-mortem rigidity is the general stiffness of 
the body after death. 
6. Muscles are of two kinds: involuntary and 
voluntary; tliese are distinguished by their struc- 
ture and mode of action. 
7. Nearly all tlie muscles used for moving bones 
are voluntary muscles. REVIEW. 
49 
8. The trachea, bronchi and the digestive canal 
have involuntary muscles. 
9. The chief uses of fat are: 
(1.) The fat, which is situated directly beneath 
the skin, prevents much of the heat of the 
body from escaping, because all fat is a 
bad conductor of heat or cold. 
(2.) Fat serves as an elastic packing material to 
wrap delicate structures, such as the palm 
of the hand and soles of the feet. 
(3.) It serves as a store of combustible mat- 
ter—that is, it may be burnt up in the sys- 
tem, and thus become a source of heat to 
the body. 
(4.) It serves to fill the cavities of the long 
bones ; it is then called marrow. 
Lesson x. 
10. To sustain a five-pound weight in the hand, 
the arm being stretched out horizontally, a muscular 
effort of about one hundred pounds is required. 
This does not include the weight of the arm. 
11. The human arm is a lever of the third class, 
the fulcrum lies in the slioulder-joint, and the power 
between the fulcrum and the weight. 
12. Muscles usually terminate in tendons. 
13. Tendons connect bones with muscles; liga- 
ments connect bones with bones. 50 
FIRST LESSORS IN PHYSIOLOGY. 
14. Walking consists— 
(1) In the lifting of the body ; 
(2) In the forward motion of the body ; 
(8) In the forward swinging of the leg. 
Lesson xi. 
15. The erect position of the body is the result of 
the combined action of the muscles. 
16. Connective tissue is that tissue which invests 
nearly all the parts of the body. 
17. The properties of connective tissue vary ac- 
cording to its uses. 
18. The muscles of the eye roll the eye-ball, move 
it slightly forward and backward, and raise and 
lower the eye-lids. 
19. The uses of the muscles are— 
(1) To produce motion; 
(2) To hold the limbs in position ; 
(8) To protect the skeleton. 
20. Human labor should be performed with con- 
tinuance and regularity. The forces of man must 
not be exhausted further than rest and food can re- 
place them day by day. THE SKIN. 
51 
LESSON XIII. 
THE SKIN—HAIR AND NAILS—EXCRETION OF THE 
SKIN. 
6. Experiment.—A piece of fresh animal skin, 
put in water, will swell up without dissolving. If 
now the skin be boiled in the water for several 
hours, most of it will dissolve, and on allowing the 
liquid to cool, a gelatinous substance is obtained. 
When dried, this forms the well-known glue. Near- 
ly all connective tissue yields the same result if 
treated in a like manner. 
The skin is the external covering of the body. It 
consists of two layers—the outside skin or the epi- 
dermis, and the inner one or dermis. The epider- 
mis contains coloring matter, which gives rise to 
shades of tint in the skin of both individuals and 
races. It is of different thickness on different por- 
tions of the body; the more it is subjected to fric- 
tion and pressure, the more does it grow—that is, 
the more does it become thick and horny. 
The epidermis serves to protect the sensitive low- 
er skin or dermis, and to moderate the evaporation 
of fluid from the blood vessels. 
The dermis serves to invest the secretion glands; 
on its surface are the sensitive touch-corpuscles. 52 
FIRST LESSONS IN PHYSIOLOGY. 
The dermis is the deeper portion of the skin; it is 
denser, more elastic and more tender than the epi- 
dermis. When cut it bleeds very freely; the epi- 
dermis does not bleed at all. In sharpening a pen- 
cil the outer skin is frequently cut, and no notice 
taken of it unless the knife enters a shade deeper, 
causing pain and flow of blood. 
The general properties of the skin are toughness, 
flexibility and elasticity. Owing to the first, it 
serves as the protecting cover of the body; in virtue 
of the second, it shields the inner parts from vio- 
lence ; and, on account of the last, it yields readily 
to the movements of the body. But it serves yet 
another purpose not less important; it is the princi- 
pal organ of touch (Lesson XXXI). 
The hair and nails are peculiar forms of the epi- 
dermis. The former is composed of horny scales 
and cells, closely packed together. The root of a 
hair, together with the root-sheath in which it is im- 
bedded, may be seen when a hair is pulled out. 
Nails grow, like hair, by the constant addition of 
cells from beneath and behind, which take the 
place of portions worn away or cut off. 
The secretion of the shin consists of two differ- 
ent fluids; one oily, the other watery. The oily 
one is secreted mostly in the scalp and the face, 
where the skin is largely supplied with hair. The 
other is called perspiration or sweat, the two terms 
being habitually taken synonymously, although 
there is this difference between them perspiration SECRETION OF THE SKIN. 
53 
is an insensible excretion, which evaporates on the 
skin ; sweat is a sensible secretion, composed of the 
same fluid as the other, but appearing on the skin 
in the form of drops. The passage of these fluids 
is effected by a multitude 
of fine canals or pores 
(Fig. 11) in the skin. Per- 
fect health requires clean- 
liness, so that the activity 
of the pores shall not be 
impeded. 
The quantity of water 
lost by transpiration de- 
pends, like all evaporation 
in the open air, upon the 
temperature, the satura- 
tion and the stillness of 
the atmosphere. In hot 
weather the quantity of 
excretion from the skin 
is greater than in cold. 
When the atmosphere is fully saturated with watery 
vapor, perspiration does not evaporate; and the 
consequence is an almost insufferable sensation of 
heat. The same holds true when, owing to the ab- 
sence of currents of air, the watery vapors of per- 
spiration remain around the person instead of being 
constantly displaced by fresh, that is, less satu- 
rated air. 
Fig.ll. 
. Epidermis. 
. Dermis. 
. Glands for 
the Hair. 
_ Perspiration 
Glands. 
. Hair. 
Sectional View of the Human 
Skin, Highly Magnified. 
Read How to Bathe. E. P. Miller. Miller, Haynes & Co., N. Y. FIRST LESSONS IN PHYSIOLOGY. 
LESSON XIY. 
THE BLOOD. 
7. Experiment.—Allow the blood of an animal 
to remain quietly in a vessel. In a few minutes it 
will coagulate, separating into two substances— 
a solid and a liquid. 
The solid has a dark-red color, and is a sort of 
jelly, often called the clot. The red color is due to 
the presence of minute bodies, which are held in 
suspension in the blood. Besides these red corpus- 
cles, the clot contains a white, fibrinous mass, or 
animal fibrine. The liquid is called serum, which 
has a yellowish color; but if, by boiling it, we re- 
move its water, it will coagulate to a white jelly, 
composed of albumen. 
The composition of blood that lias remained 
standing for some time is, therefore, as follows: 
Clot. 
Blood Corpuscles (red and white). 
Animal Fibrine. 
Blood. 
W ater. 
Albumen. 
Serum. 
It is characteristic of the red blood corpuscles 
that iliey always contain iron. THE BLOOD. 
55 
The specific gravity of blood (at a temperature of 
60° F.) is about the same as that of water. The 
temperature of the blood in the human body is 
generally 100° F. In the animal it has an odor 
faintly resembling that of the animal from which 
it came. 
The quantity of blood in the living body is diffi- 
cult to ascertain; it has been estimated at about 
one-tenth of the weight of the entire body. In a 
thousand parts of weight of blood seven hundred 
and eighty-four parts are water, one hundred and 
thirty parts are red corpuscles, and the remainder 
is composed of albumen, fibrine, fat, and other 
matters. The proper composition of the blood is 
one of the three most important items in the 
health of man. The ravages of cholera and of 
similar diseases seem to result from a decomposi- 
tion of this life-giving liquid. It will be seen, fur- 
ther on, that the health of the blood depends largely 
upon our food and upon the air we breathe. 
The red corpuscles of the human blood are cells 
of different sizes, having the form of discs, each of 
which has an area of nearly of a square 
inch, and a thickness of about tuW of an inch. 
They possess the remarkable property of adhering 
together in columns, like rolls of pennies ; these 
rolls, moreover, join at their ends so as to cluster 
together, forming a sort of network (Fig. 12). 
Besides the red, there are white corpuscles in the 
blood. They differ from the former in their num- 56 
FIRST LESSONS IN PHYSIOLOGY. 
ber being much smaller than that of the red; for 
every five hundred red ones there exists, perhaps, 
one white corpuscle. During disease this ratio may 
increase to ten, and even more, for every five hun- 
dred. They are larger than the red corpuscles, and 
possess the peculiarity of alternately contracting 
and dilating, and otherwise changing their forms. 
In Fig. 13, B, there are four white, in A C, four 
red corpuscles, as seen through a microscope of 
very high magnifying power. 
Fig. 12. 
Fig. 13 
The use of these little bodies is not well deter- 
mined. The main purpose of the red seems to be 
to convey oxygen from the lungs to all parts of the 
body. 
The gases contained in the blood are carbonic 
acid, oxygen and a small quantity of nitrogen. 
One hundred volumes of blood contain about fifty 
volumes of these gases, collectively. THE BLOOD. 
57 
Of the uses of the Mood when in the healthy state, 
the following four may here find a place : 
(1) It is a source of nutritive material, whence the 
different parts of the body constantly draw for their 
maintenance. 
(2.) It keeps all parts of the body warm and 
moist. 
(3.) It conveys oxygen to those of the tissues 
which need this element. 
(4.) It collects refuse from all parts of the body, 
and convejrs the substances to places whence they 
may be discharged. 
In the next Lesson we shall learn something about 
the manner in which the blood circulates through 
the body. 58 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XY. 
THE CIRCULATION OF THE BLOOD.—I. 
8. Experiment.—Cut open a fresh plant, and 
observe its juice. Next open an insect for the same 
purpose ; it contains a watery, almost colorless juice 
or blood. Then cut open a fish ; its blood is cold. 
Lastly, procure some red, warm blood of a recently 
killed bird, or quadruped. 
The preceding shows that organisms have a fluid 
circulating through the body. 
Man and the higher order of animals alone pos- 
sess warm blood. The ‘vital fluid’ has a definite 
order in which it travels through the animal sys- 
tem. The circulation in the human body is the same 
as in mammals and birds. 
An uninterrupted current of blood through the 
body must be maintained. This is evident from the 
uses of the blood enumerated in the preceding Les- 
son. The question now arises, How does nature 
obtain such an unceasing stream rushing through 
countless tubes and channels ? 
The heart (represented by 1, 2, 3, 4, in Fig. 14) is 
a hollow muscle of about the size of its owner’s fist. 
This muscle has involuntary action, consisting of 
alternate contraction and dilatation, which goes on 
without interruption until death. Owing to the con- CIRC TIL ATIOX OF THE BLOOD 
59 
F&14 
traction, the blood is 
expelled from the 
heart through arteries 
and owing to the dila- 
tation,it returns to the 
heart through veins. 
The heart is divided 
by a partition into 
two sides, right 
and left (Figs. 14,15). 
These two sides do 
not communicate with 
each other. Each of 
them has been sub- 
divided into two por- 
tions, an upper and a 
lower, or into the 
auricle (1 or 2) and 
ventricle (3 or 4) re- 
spectively. The heart, 
therefore, contains 
two auricles (1,2) and 
two ventricles (8, 4). 
While the two divi- 
sions right and left 
are entirely separate 
Venous Blood. 
Arterial Blood. 
Capillaries. 
The Heart and the Lungs. 
Viewed from behind, so that 
the position of the observer 
corresponds with that of the 
figure. 60 
FIRST LESSONS IN PHYSIOLOGY. 
from one another, each auricle communicates with 
the ventricle of the same side. The opening, how- 
ever, through which the communication takes place 
is so constructed that it acts like a valve (com- 
pare First Lessons in Physics, p. 72); it allows the 
blood to pass from the auricle to the ventricle, but 
not in the opposite direction. 
The course of the blood 
from auricle to ventricle 
is in the same direc- 
tion on each side. 
The blood in the 
right auricle (2) is urged 
into the right ventricle 
(4), whence it passes 
through a large artery 
(pa) into the capillaries 
of the lungs, where it 
absorbs oxygen, and gives out carbonic acid. This 
artery is the pulmonary artery, one of the few 
arteries carrying venous blood, and called an artery 
simply on account of it being constructed like the 
arteries. The blood is then gathered up again and 
conveyed in large veins (pv) to the left auricle. From 
the left auricle it emerges into the left ventricle (3), 
the strongest of the four divisions, and thence into 
the aorta, a, the strongest of the arteries. The aorta, 
distributes it all over the system, to the capillaries 
of every portion of the body. In these capillaries 
the blood becomes impure, and after leaving them 
it passes through the large veins (vc) back into the 
right auricle (2), whence we supposed it to start. 
Fig.15. 
The Heart and Large Blood Vessels. CIRCULATION OF THE BLOOD. 
61 
As stated before, the chief propelling force for the 
incessant torrent of blood through the body lies in 
the muscular substance of the heart. But there are 
several helpers which must not be disregarded : 1st, 
the elastic walls of the arteries (they are not un- 
yielding like gas pipes); 2d, the pressure of mus- 
cles upon some of the veins; and 3d, the contraction 
and expansion of the chest in breathing. These 
aids will be better understood hereafter. 
The function of each subdivision of the heart 
may be stated thus : 
a. The right auricle receives the venous blood of 
the whole body and conveys it to the right ventricle. 
h. The right ventricle impels the venous blood 
through an artery into the lungs. 
c. The left auricle receives arterial blood flowing 
to it through veins from the lungs. 
d. The left ventricle forces the blood into the 
aorta, which distributes it over all parts of the 
body. 
In comparing the functions of these subdivisions 
with one another it is found that— 
I. The auricles receive blood; 
The left auricle receives arterial blood from 
the lungs; 
The right auricle, venous blood from the en- 
tire body. 
II. The ventricles convey away blood ; 
The left ventricle conveys away arterial blood 
to the entire body ; 
The right ventricle, venous blood to the lungs. 62 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XVI. 
THE CIRCULATION OF THE BLOOD.—II. 
Examine the movements of the heart by placing 
the fingers between the fifth and sixth ribs, slightly 
to the left of the breast-bone (as the lower part of 
the heart inclines a little toward the left). Each 
contraction of the heart will then be distinctly felt, 
because the point of the heart strikes against the 
wall of the chest. 
The heart of a living animal, if quickly removed, 
will continue pulsating for some time. Each pulsa- 
tion commences at the two auricles, and thence 
passes to the two ventricles. That is to say, each 
pulsation of the heart consists of—1st, a simultane- 
ous contraction of both auricles; 2d, immediately 
after this a simultaneous contraction of both ventri- 
cles : and third, a moment of rest or relaxation. 
After this rest the contractions commence again in 
the same order as before, and the relaxations occur 
also in the same order as before. The work of the 
heart is carried on, as all labor should be, regularly 
and continuously, with due regard to rest. 
The two contractions of the heart with its subse- 
quent repose, are often represented by two short 
marks and a rest, thus : o w — . The contraction 
of either auricle or ventricle is called its systole; THE CIRCULATION OF THE BLOOD. 
63 
the pause during the dilatation of either auricle or 
ventricle is called the diastole. This disastole or 
pause occupies about the same length of time as 
the two systoles together; so the heart’s action has 
a certain rhythm. 
The action of the heart may now be explained. 
It is filled with blood, and the first contraction, or 
the systole of the auricles, happens. The auricles 
are, as it were, pressed together, and the liquid 
within is forced out. Where can it go ? On exam- 
ining Fig. 14 two outlets are found to exist. It may 
pass back into the veins, or else descend into the 
ventricles. The amount of resistance encountered 
in each direction will decide the question. The re- 
sistance encountered toward the veins is very great, 
because exerted by the blood in all the veins ; that 
encountered toward the ventricles will be exceed- 
ingly small, because, in the first place, the valves 
leading into the ventricles are open ; in the second 
place, the walls of the ventricles, in their relaxed 
state, are easily expanded; and in the third place, the 
resisting pressure of the arterial blood is rendered 
naught by the valves between the ventricles and 
arteries being closed. For these reasons only very 
little blood will pass back to the veins ; nearly all 
of it rushes at once into the ventricles. When the 
ventricles are thus filling they become expanded, 
and the blood getting behind the valves which 
separate each auricle from its ventricle, the ven- 
tricles are soon closed. The contraction of the 
auricles now ceases, their walls relax, and immedi- 
ately blood from the veins enters them, slowly ex- FIRST LESSONS IN PHYSIOLOGY. 
panding them again. The auricular systole is now 
over. 
The next movement of the heart is the contrac- 
tion of both ventricles. The walls of the ventricles 
are strong and thick ; the pressure, therefore, which 
they produce in suddenly contracting is very great, 
and has the effect of shutting up the auriculo-ven- 
tricular valves so that not a drop of blood can enter 
the auricles. But it is toward the arteries that the 
ventricles meet with most of the resistance. There 
is the resisting pressure of the blood in the arteries, 
a pressure which is very great because it is made 
up—first, of the weight of the blood; second, of 
the resistance of the walls of the arteries to further 
expansion; third, of the friction of the blood in the 
capillaries. All this explains why the walls of the 
ventricles are built so very strong: they have more 
work to perform than the auricles. It also shows 
the necessity of the valves between the auricles 
and ventricles , and that no valves are needed be- 
tween the auricles and veins. The auriculo-ventri- 
cular valves act like the lower valve in a pump. 
The whole office of the auricles seems to be to fill 
the ventricles. And the contraction of the left ven- 
tricle forces the blood into the arterial system of 
the body, while the contraction of the right ventricle 
impels the blood into the artery of the lungs. This 
simultaneous contraction of the ventricles forms the 
ventricular systole. 
The arteries receive a fresh supply of blood at 
every systole of the ventricles; during a part of the CIRCULATION OF THE BLOOD. 
65 
time in which they transmit the shock, the diastole 
of the heart occurs. Each ventricle contains about 
three ounces of blood ; the whole of this passes, at 
each contraction, into the respective arteries. The 
great pressure of this quantity of blood (about one- 
fifth of the pressure of the atmosphere) suddenly 
forced into the main arteries, necessarily distends 
them, because they are elastic and yielding; but a 
reaction takes place, and the elastic walls of the 
arteries contract again. This contraction has two 
effects in opposite directions: it causes, first, the 
valves between the arteries and ventricles to close 
instantly ; second, the blood to pass from the larger 
to the smaller arte- 
ries. Thence the 
fluid enters the rami- 
fication of the capil- 
laries (Fig. 16). A 
little reflection will 
show that a corre- 
sponding quantity of 
blood passes at the 
same time from the 
capillaries through 
the veins back to- 
ward the heart. The effect, then, of the ventricular 
systole is—1st, the propulsion of blood through the 
arteries into the capillaries; and 2d, the return of 
the fluid from the capillaries through the veins to 
the heart. 
Fig. 16 
CAPILLARIES. 
The impulse given at every ventricular systole to 66 
FIRST LESSONS IN PHYSIOLOGY. 
the blood in the aorta is spent in urging the blood 
forward through the arteries ; and, next, in distend- 
ing the elastic walls of the arteries. This sudden 
expansion produces a sudden recoil, and gives rise 
to a phenomenon, which is called the pulse. The 
pulse proper is the expansion of the artery, felt on 
examining the artery. Each pulsation naturally 
means a systole of the ventricles. Such pulsations 
may be felt wherever arteries are exposed to the 
touch, as on each upper side of the neck, in front of 
the ear, or above the wrist. At the wrist the pulse 
is felt to be a little later than at the heart or middle 
of the neck. It occurs later, according to the dis- 
tance from the heart at which the artery is examin- 
ed. To feel the pulse, the wrist is selected by 
physicians for convenience sake. The pulse is the 
index of the motions of the heart. Its regularity, 
strength, fullness, and a number of peculiarities, in- 
dicate the state of affairs respecting the heart and 
its fluid. 
The sounds of the heart may be distinctly heard 
by placing the ear closely over the heart. They 
should occur with great regularity—first, a prolong- 
ed, dull sound, somewhat like that of the word 
lubb ; then a short and sharp sound, nearly like 
that of dub; then comes a pause; then the long 
sound again, and then the short sound; then the 
pause, the long sound, and so on. The sharp, short 
sound comes from the sudden closing of the valves 
between the ventricles and the arteries; the cause of 
the long sound is not fully known, as yet. 
The capillaries are pulseless, because on reaching CIRCULATION OF THE BLOOD. 
67 
them the shock is spread over a large network of 
capillary tubes; this makes its effect imperceptible. 
For the same reason, the blood in the capillaries 
flows steadily, while from a severed artery it jets 
forth in jerks. The elasticity of the arteries seems 
to do for the blood what an air chamber does for 
the water of a pump. 
From what has been said in regard to the arteries, 
their uses chiefly are—first, to convey blood to the 
system, and secondly, to convert the jerking motion 
of the blood into a uniform flow. 
9. Experiment.—Clasp the lower part of the arm 
tightly a little above the wrist; the veins on the 
back of the hand will soon distend, and knotty 
points become visible. When the pressure is re- 
moved they will empty themselves, and the swelling 
disappears. Now, why did this not completely 
check the circulation of the blood ? There are two 
reasons : In the first place, the veins communicate 
with each other by means of many branches, so that 
whenever the blood, for any reason, be stopped in 
one vein, it at once passes through branch vessels to 
another, unimpeded vein, and finally to the heart. 
But it may be argued that in the above experiment 
the arm had been encircled with so much pressure 
that even the branch vessels were closed. Circula- 
tion would, nevertheless, have continued, because, in 
the second place, the veins are provided with valves 
(Fig. 17) which are open as long as the fluid flows 
toward the heart, but which close when it moves in 
the opposite direction. Those knotty places were 68 
FIRST LESSONS IN PHYSIOLOGY. 
the closed valves, preventing the backward flow of 
the blood to the capillaries. Were it not for this 
valvular action in the veins, any such disturbance 
as the one occasioned by the experiment, would 
Ficf.17. 
impel the blood to the capillaries, wdiere it would 
resist, and finally overcome, the onward motion of 
the blood in the arteries, which would speedily in- 
terrupt the circulation. 
The frequency of pulsations depends upon the 
age, sex and health of a person. During the first 
years of life about 130 pulse-beats may be counted 
in a minute, while twenty years later the same per- 
son’s pulse will beat nearly 70 times, and increase 
again toward old age. The pulse of women beats 
more rapidly than that of men. 
Read First Series of Science Lectures. JohnHeywood: Deansgate, 
Manchester. REVIEW. 
69 
LESSON XVII. — REVIEW. 
Lessox xiii.— 
1. Connective tissue, when boiled, yields gelatine. 
2. The skin consists of the dermis and epidermis. 
3. The use of the dermis is, to invest the excre- 
tion glands, and to bear the toucli-corpuscles. 
4. The use of the epidermis consists in protecting 
the dermis, and limiting the evaporation from the 
blood vessels beneath. 
5. The general properties of the skin are—1st, 
toughness, which enables it to serve as a cover to 
the body ; 2d, flexibility, by which it protects the 
muscles ; and 3d, elasticity, by which it yields read- 
ily to the movements of the body. 
6. The skin is the principal organ of touch. 
7. The hair and nails are peculiar forms of the 
epidermis. 
8. The excretion of the skin consists of oily mat- 
ter, and of perspiration or sweat. 
9. The amount of transpiration depends upon the 
temperature, saturation and stillness of the atmos- 
phere. 
10. The skin excretes about one-fiftieth as much 
carbonic acid gas as the lungs. 70 
FIRST LESSONS IN PHYSIOLOGY. 
Lesson xiv.— 
11. Animal blood, after standing for some time, 
contains—1st, red and white corpuscles; 2d, animal 
fibrine ; 3d, water ; and 4th, albumen. The first two 
form the clot, the remaining two the serum. 
12. The specific gravity of blood = 1, very near- 
ly ; its temperature = 100° F., nearly. 
13. The living body contains a quantity of blood 
of about one-tenth of its own weight. 
14. A thousand parts of weight of blood contain 
780 parts of water, and 130 parts of red corpuscles; 
the remainder is composed of albumen, tibrine, fat, 
and other matters. 
15. The proper composition of the blood is one of 
the three most important requirements for health. 
(For the other two see pp. 81 and 88.) 
16. The red blood corpuscles differ from the white 
in this: that they are smaller in size but larger in 
number, and of a less changeable nature. 
17. The use of the red corpuscles seems to be to 
convey oxygen from the lungs to all parts of the 
body. The use of the white is not fully known. 
(Compare Lesson XXVII.) 
18. The blood contains, dissolved within it, three 
gases : carbonic acid, oxygen, and a small quantity 
of nitrogen. 100 volumes contain about 50 volumes 
of these gases, collectively. REVIEW. 
71 
19. The following are four uses of the blood: 
(1) It feeds the different parts of the body, 
which depend upon it for their main- 
tenance. 
(2) It provides the entire body with warmth 
and moisture. 
(3) It carries oxygen to the tissues which need 
this gas. 
(4) It gathers refuse matter throughout the 
body, and conveys it where it may be 
discharged. 
Lesson xv. 
20. Organisms of every kind need a fluid which 
circulates through the body and nourishes all the 
parts of the body. 
21. The human heart is a small hollow muscle, 
with involuntary action consisting of alternate con- 
traction and dilatation. 
22. Arteries are vessels conveying the blood from 
the heart; veins are vessels conveying the blood to 
the heart. 
23. The force which propels the blood through 
the body lies in the substance of the heart. Its 
assistants in this are: 1st, the elastic walls of the 
arteries ; 2d, the muscular pressure upon some of the 
veins; 3d, the contraction and expansion of the 
chest in breathing. 72 
FIRST LESSONS IN PHYSIOLOGY. 
24. The right side of the heart is entirely separ- 
ated from the left side. Each is subdivided into an 
auricle and ventricle. The heart contains two auri- 
cles and two ventricles. 
25. Each auricle communicates with its ventricle, 
below, by means of an aperture provided with a 
valve. 
26. The circulation of the blood takes place in the 
following manner: The blood leaves the right auri- 
cle of the heart and enters the right ventricle; 
thence it flows through an artery to the lungs ; from 
the lungs it passes through several veins to the left 
auricle, whence it is impelled into the left ventricle. 
It then rushes into the aorta, and is forced through 
every portion of the body. It finally returns through 
veins to the right auricle, whence we supposed it 
to start. 
Lesson xvi. 
27. A pulsation of tlie heart consists— 
(1) Of a contraction of the auricles ; 
(2) Of a contraction of the ventricles; 
(3) Of a pause. 
28. The contraction of either auricle or ventricle 
is called its systole ; the pause during the dilatation 
of either is called the diastole of the heart. 
29. During the auricular systole the blood rushes 
from the auricles into the ventricles. REVIEW. 
73 
30. During the ventricular systole the blood is 
forced into the arterial systems of the body and 
lungs. 
31. The contraction of the arteries has two effects 
in opposite directions : 1st, the closure of the auri- 
culo-ventricular valves ; 2d, the propulsion of blood 
from the larger to the smaller arteries. 
32. The general effect of the ventricular systole 
is the propulsion of blood through the arteries into 
the capillaries, and back through the veins to the 
heart. 
33. The pulse is the expansion of the artery, 
caused by the passage of a wave of blood at every 
ventricular systole. 
34. The sounds of the heart are two : a long sound 
and a short one ; they are succeeded by a rest. 
35. The capillaries are pulseless. 
36. The chief uses of arteries are: 1st, to convey 
the blood to the system; 2d, to produce a uniform 
motion of the blood. 
37. Whenever the flow in the veins of a limb is 
checked, the branch-vessels and the valves of the 
veins prevent the interruption of the circulation. 74 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XVIII. 
THE LUNGS. 
The blood nourishes the different parts of the 
body (Lesson XIV.), and at the same time removes 
effete matter—that is, all such particles as have 
served their function in the body. This gives rise 
to two distinct kinds of blood, the arterial or nutri- 
ent, and the venous, the carrier of waste matter. The 
most important difference between the two is, that 
venous blood contains less oxygen and more car- 
bonic acid gas than the arterial. The latter is of a 
scarlet color, but in passing through the capillaries 
of the body it is converted into venous blood, at 
the same time becoming darker. The venous blood 
passes from the heart to the lungs, where it is con’ 
verted into arterial blood by the absorption of 
oxygen gas. This conversion is mainly effected by 
the peculiar structure of the lungs ; it is aided by 
the acts of inspiration and expiration, as well as by 
other processes. The conversion takes place dur- 
ing the passage of venous blood through the capil- 
laries of the lungs (Fig. 21). 
The lungs occupy the greater portion of the chest; 
they are situated on both sides of the heart (Fig. 
18). They receive air through the trachea and the 
larynx ; these communicate with the external air by 
two channels—the mouth and the nasal tubes. The THE LUNGS. 
75 
month can be opened or closed at will; the nasal 
passages are not subject to the will. The left lung 
consists of two separate portions called lobes; 
the right lung has three lobes (See Fig. 18). Each 
lung is composed of a spongy, elastic substance, 
and is often compared to a bag. Each is attached 
to one of the two bronchi (Fig. 19, c). These bron- 
chi, or bronchial tubes, after entering the lungs, 
Fig.19. 
Fig.18. 
Lungs, Trachea and Heart, 
a Aorta. a Arteries. 
b Trachea. vc Veins entering 2. 
2 Right Auricle. 
3 Left Ventricle, with Left Auricle above. 
4 Right Ventricle. 
Pulm. Art. and Pulm. Veins. 
{pa and pv, Fig. 15) visible. 
Trachea, Bronchial Tubes 
and Left Lung, 
a Larynx. 
b Trachea. 
c Right Bronchus. 
d Small Bronchial Tubes. 
e Minute Bronchial Tubes, 
in. diameter). 76 
FIRST LESSONS IN PHYSIOLOGY. 
divide and subdivide into a great number of smaller 
and smaller tubes (d), which penetrate to every part 
of the lungs. The trachea and bronchial tubes, owing 
to their cartilages, are unyielding, so as to remain 
permanently open; the finer tubes (e), about of 
an inch in diameter, have no cartilages; therefore, 
they may be closed by contraction. The minute 
portion of a lobe is called a lobule; a lobule is a 
little lung of itself. Each minute bronchial tube 
passes into a lobule. After entering the lobule, the 
small bronchial tube divides still further into small- 
er branches (Fig. 20), whose walls at length become 
exceedingly thin. Each 
such minute branch widens 
at its end into an air-cell. 
An air-cell, therefore, is a 
minute cavity of about of 
an inch in diameter (Fig. 
21). The air-cells are ar- 
ranged singly, or in groups 
so that a series of cells open 
into the same bronchial 
tube. The lungs are made 
up of air-cells. Each air-cell 
carries a network of capil- 
laries—that is, of minute blood vessels (of about 
inch diameter; this network is so dense that 
its open spaces, or meshes, are even narrower than 
the capillaries themselves. Between the air in the 
cells, then, and the blood in the capillaries are but 
two delicate membranes, that of the cells and that 
of the capillaries. 
Fig. 20.—Bronchial Tubes, with 
Air-Cells (magnified 15 times). THE LUNGS. 
77 
The purpose of this network of capillaries is to 
thoroughly expose the blood to the action of the air. 
This is accomplished, 1st, by spreading the blood 
over a large surface; 2d, spreading it in thin 
Fig.21. 
Fig. 21. —Air-Cell, with Capillaries. 
streams ; 3d, protecting it by merely a very delicate 
cover. The renewal of the blood in these capillaries 
is a result of the circulation ; the renewal of the air 
in the cells is the result of respiration. The number 
of respirations is from fifteen to eighteen a minute, 
and varies slightly, according to the age of life. 
Venous Mood absorbs oxygen in the lungs through 
the membranes separating it from the air, while at 
the same time it parts with carbonic acid gas and 
water xapor. This influx of oxygen into, and efllux 
of carbonic acid gas and water-vapor out of, the blood 
form the most important part of the respiratory pro- 
cess. They purify the blood in changing it from 
venous into arterial, the means of purification being 
the peculiarly delicate membranes mentioned above. 78 
FIRST LESSONS IN PHYSIOLOGY. 
(See also page 80.) But the action of the mem- 
branes alone would suffice only for a short time, since 
the carbonic acid gas accumulates very rapidly, 
and in large quantity ; and also because oxygen is 
needed all over the system at every instant of time. 
Hence we need a rapid removal of the carbonic acid 
gas from the lungs, and at the same time an inces- 
sant importation of fresh oxygen. We find that the 
clearing away of the one and the supply of the 
other, are accomplished incessantly by the act of 
inspiration and expiration. The most powerful aids 
in this process are the elasticity of the lungs, the 
mobility of the sides of the chest, and the mobility 
of the diaphragm. The diaphragm is a strong mus- 
cle separating the chest from the abdomen, thus 
forming the floor of the chest. Its special business 
is to assist respiration. 
To avoid chilling the lungs, cold air should be 
inspired through the nasal passages; not through 
the mouth. 
Read Consumption : Dr. C. Both. Lee & Shephard: New York. 
Read Science Lectures—First Series. Heywood : Manchester. RESPIRATION. 
79 
LESSON XIX. 
RESPIRATION. 
The inspiration of air into the lungs is effected 
in this way: The lungs are in close contact with 
the inner side of the chest-walls ; the lower portion 
of the lungs is in close contact with the diaphragm. 
It is evident that whenever the chest-walls move, the 
lungs must also move, and rice rersa. So, when the 
chest expands the lungs expand; or, more properly 
speaking, they are enlarged by a quantity of air 
which rushes through the larynx, trachea and bron- 
chi, to fill the lungs (compare First Lessons in 
Physics, Lesson XIX., p. 71). 
In expiration the chest-walls contract; the lungs 
contract likewise—that is. a quantity of air is eject- 
ed from the lungs and forced to pass through the 
bronchi, trachea and larynx, this being the only 
communication between the lungs and the external 
air. The act of expiration is followed by a short 
rest. 
The widening of the chest during inspiration is 
owing to the motion of the ribs ; the lengthening of 
the chest during inspiration, to the descent of the 
diaphragm. In ordinary inspiration both chest 
and lungs return to the state of rest by their elastic 
ity. Ordinary inspiration is nearly exclusively ef- 80 
FIRST LESSONS IN PHYSIOLOGY. 
fected by the mobility of the diaphragm and the 
ribs. In very deep inspiration, the dimensions of 
the chest are increased still further by the ascent of 
the clavicle and the stretching of the vertebral col- 
umn. 
The rhythm observable in the respiratory process 
is inspiration, expiration, pause ; that of the heart 
being, in a similar manner, auricular systole, ven- 
tricular systole, pause. 
Inspired, and expired air differ from each other 
chiefly in the following points : 
(1.) Expired air has nearly the same temperature 
as the blood, whatever may be the temperature of 
the external air. 
(2.) Expired air is always filled with water-vapor. 
(3.) Expired air always contains more carbonic 
acid gas and less oxygen than inspired air. One 
hundred parts of air breathed once have lost about 
five parts of oxygen, and gained a little less than 
five parts of carbonic acid. This is shown by the 
following statement: 
10,000 parts of atmospheric air contain 
Oxygen. Nitrogen. 
2080 7916 
Carb. Acid. 
4 
10,000 parts of expired air contain (nearly) 
1600 7916 
484 
The absorption of oxygen by the venous blood in 
the lungs is accomplished by the red blood corpus- 
cles. Although separated from the oxygen by the 
thin walls of the air-cells, they seize upon the oxy- 
gen, attach themselves to it, and make it accompany 
them on their journey through the system. The 
activity of the oxygen is thus highly increased, and 
causes very important chemical changes in the body RESPIRATION. 
81 
as it unites with the carbon particles in the blood, 
gradually changing them into carbonic acid. This 
gas remains dissolved in the blood, giving the latter 
its dark-red color; but upon arriving in the lungs 
it is liberated, passes out as the oxygen passes in, 
and is removed by expiration. 
Ventilation.—Since about four hundred cubic feet 
of air pass through the lungs of an adult in twenty- 
four hours, a constant supply of oxygen—that is, 
of fresh air—is one of the most essential require- 
ments of health. And since carbonic acid gas is 
unfit for respiration, it follows that every inhabited 
room should have an open space to admit fresh air, 
and an open space to convey away the waste pro- 
ducts of respiration; both spaces must directly or 
indirectly communicate with the atmosphere. But 
the presence of a surplus of carbonic acid is less in- 
jurious than the absence of the normal amount of 
oxygen. A person living in badly ventilated apart- 
ments vitiates his blood, predisposes his system to 
disease, and thus virtually shortens his life. A 
total lack of air would result in speedy death. 
Coughing is a quick and forcible expiration or 
series of expirations ; the glottis is closed, and a 
current of air is violently forced through it in the 
mouth. This causes the well-known sound accom- 
panying coughing. 
Sneezing is the same process, but with the cavity 
of the mouth closed, the forcibly ejected air passing 
through the nose. 82 
FIRST LESSONS IN PHYSIOLOGY. 
Sighing consists of a slow, deep inspiration, fol- 
lowed by quick and short expiration. 
Laughing is a rapid succession of short and forci- 
ble expirations, each accompanied by a ringing 
sound. 
Sobbing is a series of abrupt, inspiratory acts, 
mostly produced by strong contractions of the dia- 
phragm, and accompanied by sounding vibrations 
of the vocal chords. 
Snoring results from the current of expired air 
striking against the soft palate, and causing it to 
vibrate. 
Respiration by means of the shin.—Through the 
skin of the body oxygen of the air enters, and 
passes to the blood; and carbonic acid gas and 
water-vapor emerge through the skin from the body. 
The quantity of water-vapor perspired in twenty- 
four hours amounts to about If pounds. (Compare 
page 69.) 
The proper supply of oxygen forms one of the 
three most important requirements for health. (For 
the remaining two see pp. 70 and 88.) 
THE LUNGS AND THE HEART COMPARED. 
Three points in common : 
1. Both operate by expansion and contraction. 
2. Both are involuntary organs; that is, on ordi- 
nary occasion they act independently of the will. 
3. Both are indispensable to the maintenance of 
life. RESPIRATION. 
83 
Three points of difference : 
1. The lungs contain air; the heart contains 
blood. 
2. The lungs contain bronchial tubes, air-cells 
and blood-vessels; the heart has two parts, called 
the right and the left side, each part being again di- 
vided into auricle and ventricle. 
3. The lungs purify the blood; the heart propels 
the blood through the body. 
Read Cough and Colds. Hurd & Houghton : New York. 
Read Ventilation. Popular Science Monthly, Vol. I., p. 356. 84 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XX. —REVIEW. 
Lesson xyiii.— 
1. There are two kinds of blood, the arterial and 
venous. The main difference between them is, that 
the latter contains less oxygen but more carbonic 
acid gas than the former. 
2. Venous blood passes from the system to the 
heart, and from the heart to the lungs ; arterial, from 
the lungs to the heart, and from the heart to the 
system. 
8. The lungs consist of (1) the left lung, and (2) 
the right lung. The former has two and the latter 
three lobes. 
4. Each lung is attached to a bronchus, each of 
which is again subdivided into a great number of 
smaller branches, called bronchial tubes. 
5. An air-cell is a cavity or the dilated end of a 
minute bronchial tube, and about of an inch in 
diameter. The lungs are made up of air-cells. 
6. The capillaries in the lungs serve to expose the 
blood to the action of the air. This is done by (1) 
spreading it over a large surface, (2) spreading it in 
thin streams, (3) protecting it by merely a delicate 
cover. 
7. The renewal of the blood in these capillaries is 
a result of the circulation ; the renewal of the air in 
the cells is the result of respiration. REVIEW. 
85 
8 The influx of oxygen into, and the efflux of 
carbonic acid gas and water-vapor out of, the blood 
form the most important part of respiration. 
9. The act of inspiration supplies the lungs with 
fresh oxygen ; that of expiration removes carbonic 
acid gas and water-vapor from them. 
Lesson xix.— 
10. In inspiration a quantity of air rushes through 
the larynx, trachea and bronchi, and passes into 
the lungs, expanding and tilling them. 
11. In expiration, a quantity of air is ejected from 
the lungs by means of compression, and passes 
through the bronchi, trachea and larynx into the 
external air. 
12. The rhythm observable in the respiratory pro- 
cess is inspiration, expiration, pause. 
13. Inspired and expired air compared: 
(1.) Expired air has nearly the same tempera- 
ture as the blood, whatever be the tempera- 
ture of the external air. 
(2.) Expired air is always filled with water- 
vapor. 
(3.) Expired air always contains more carbonic 
acid gas and less oxygen than inspired air. 
14. Coughing is a quick and forcible expiration, 
or series of expirations. 
Sneezing is the same process with the mouth 
closed. 
Sighing is a slow, deep inspiration followed by 
a quick and short expiration. 86 
FIRST LESSONS IN PHYSIOLOGY. 
Laughing is a rapid succession of short and 
forcible expirations, each accompanied by 
a ringing sound. 
Sobbing is a series of abrupt, inspiratory acts. 
Snoring results from the current of expired air 
striking against the soft palate, causing it 
to vibrate. 
15. The proper supply of oxygen forms one of the 
three most important requirements for health. (For 
the other two compare pp. 55, 88.) 
16. The lungs and the heart compared. 
Three points in common: 
(1.) Both operate by expansion and contrac- 
tion. 
(2.) Both are involuntary organs ; that is, on 
ordinary occasion they act independently 
of the will. 
(3.) Both are indispensable to the maintenance 
of life. 
Three points of difference : 
(1.) The lungs contain air; the heart contains 
blood. 
(2.) The lungs contain bronchial tubes, air- 
cells and blood vessels; the heart has 
two parts, called the right and left side, 
each part being again divided into auricle 
and ventricle. 
(3.) The lungs the blood ; the heart pro- 
pels the blood through the body. RELATION OF AIR TO THE BODY. 
87 
LESSON XXI. 
AIE, AND ITS RELATION TO THE HUMAN BODY.—I. 
Wherever man sojourns, whether within doors or 
out, whether below, above, or at the surface of the 
earth, he requires, night and day, an incessant sup- 
ply of air, which he mainly uses for food, and as a 
means of cooling the body. 
(Our atmospheric air is a mixture of two gases— 
nitrogen and oxygen; only the latter is available 
for food; nitrogen is not utilized for the purpose by 
the blood. Oxygen forms one-fifth of any given 
volume of the atmosphere; nitrogen, the remaining 
four-fifths.) 
This Lesson treats of air as a means of cooling 
the body. 
The human body, in order to properly carry on 
the functions of life, requires a constant internal 
temperature, which, in summer and winter, must be 
the same. Experiments have shown this tempera- 
ture to be between 98° and 100° F.; and, as it does 
not vary under ordinary circumstances, this vital or 
animal heat, as it is called, must be generated in 
and distributed through the interior of the body at 
every instant of time. In severe cold weather the 
temperature of the air may be so low that one’s ears 
or finger-ends may be cooled a few degrees below 
98°, or even congeal; but the temperature of the 88 
FIRST LESSONS IN PHYSIOLOGY. 
interior organs and of the blood remains unchanged. 
Should the cold be very intense, however, and affect 
the body then the temperature of the 
blood will be reduced, and the consequences be 
fatal. A decrease of five degrees below the normal 
standard of temperature will cause the vital pro- 
cesses to cease. 
An increase in the temperature of the blood is 
always associated with a diseased state of the body, 
and if not overcome, in course of time, will prove 
fatal. Such an increase occurs in typhoid fever, 
often to the extent of eight degrees F. 
A temperature not varying more than one degree 
from 99° F., whatever he the temperature of the 
surrounding air, is one of the three most important 
requirements for health. 
It is obvious that the maintenance of the standard 
temperature of the body must be one of our main 
cares. Heat may be lost—I., by conduction; II., by 
radiation; and III., by evaporation. 
I. Loss OF HEAT BY CONDUCTION. 
10. Experiment.—The end of a wire held in a 
flame has a higher temperature than its nearest part 
outside the flame, while the end of the wire which is 
held in the hand is comparatively cool. We say 
now that the wire is unequally hot; and because of 
this inequality of temperature, the heat commences 
to pass from the hotter to the colder portions of the 
wire, so that, finally, the hand can no longer hold it. RELATION OF AIR TO THE BODY. 
89 
In the same manner the human body transfers 
heat to any substance in contact with it and colder 
than itself, such as air, water or clothing. 
The passage of heat from hotter to colder por- 
tions of a body, or from hotter to colder adjacent 
bodies, is called the conduction of heat. 
If, by way of experiment, we were to step from a 
heated room suddenly into an apartment whose 
temperature was 32° F., a great deal of heat would 
be conducted away from the body, and the loss 
would at once be seriously felt; but were we, in a 
heated state, to plunge into ice-cold water, the loss 
of heat would be far greater—that is, the water 
would take more heat from the body than the air, 
and we should be chilled instantaneously. This 
shows that water is a better conductor of heat than 
air (compare First Lessons in Physics, pp. 94, 95). 
It also explains why we take cold more easily in 
moist and cold weather, than in dry and cold. 
il. Loss OF HEAT BY RADIATION. 
Familiar Facts.—On a bright and calm day in 
winter we feel the sun’s rays to be quite warm, 
although the water on the ground be freezing, and 
the ice be dry and hard. The thermometer indicates 
a temperature below the freezing point, but when 
the direct rays of the sun fall on it, it rises at once, 
indicating a far higher temperature. This shows 
that the sun’s rays pass through the air without 
heating it, but that they heat any object, such as a 
solid body, which stops them. 
This passage of heat-rays from one body to an- 90 
FIRST LESSONS IN PHYSIOLOGY. 
other without affecting the air through which they 
pass is called the radiation of heat. It differs from 
conduction, inasmuch as the radiating body is not 
in contact with the body heated, while conduction 
means the passage of heat from hotter to colder 
parts of the same substance, or of adjacent bodies. 
On a cold day, if a person is seated by a window 
in a warm room, his loss of heat by radiation is only 
partial, and, therefore, more dangerous than an 
equal radiation from all parts of his body, such as 
takes place when he is walking out of doors. A par- 
tial radiation may produce a cold, and, if continued, 
entail serious injuries upon the system. 
As the human body heats the air around it by 
conduction, and as warm air has less specific weight 
than cold air, currents of warmed air continuously 
ascend along the body. These currents are interfer- 
ed with by the atmosphere, which constantly pene- 
trates to the body, becomes heated at its expense, 
and thus exerts a cooling influence upon it. Hence, 
we feel colder when windy weather sets in, although 
the thermometer shows no reduction of temperature. 
All bodies continually tend to equalize their tem- 
peratures by the diffusion of heat. This diffusion 
takes place by conduction and radiation. 
III. LOSS OF HEAT BY EVAPORATION. 
Familiar Facts.—A few drops of alcohol or 
ether, placed upon the bulb of a thermometer, will 
rapidly evaporate ; this causes an immediate reduc- 
tion of temperature, which is indicated by the ther- RELATION OF AIR TO THE BODY. 
91 
mometer. So, snow and ice, when melting on the 
ground, reduce the temperature of the air. 
Now, evaporation means the conversion of a liquid 
into the gaseous state. The conversion of solids 
into the liquid (or gaseous) state is called melting 
or fusion. 
Whenever substances evaporate or melt, they ab- 
sorb heat; this heat is taken from the adjacent 
body, and this bod.y is thereby chilled. 
In the case of the alcohol, the heat was given to 
it by the thermometer; in the case of snow and ice 
melting on the ground, the heat was communicated 
by the air. Both, the thermometer and the air, un- 
der those circumstances suffered a loss of heat; this 
is the reason why the thermometer sank, and the 
air became chilled. 
The injurious effects of ‘wet feet,’ and of gar- 
ments moistened from rain, or from having been 
worn next to the skin too long, are due to the cold 
produced by evaporation, and also to the greater 
conductive power of water. The skin must be kept 
warm, and free from moisture ; garments worn next 
to the skin should be frequently changed. A per- 
son who, with his body heated from exertion or 
rapid motion, and perspiring copiously, should en- 
ter a colder atmosphere, or be exposed to a draught, 
would lose an enormous quantity of heat, both by 
conduction and radiation. 
Diseases resulting from 4 colds ’ are among the 
most painful and dangerous. The process of ‘ cool- 
ing off ’ should at all times be carried on slowly and 
fjrcidu till v. 92 
FIKST LESSONS IN PHYSIOLOGY. 
LESSON XXII. 
AIR, AO ITS RELATION TO THE HUMAN BODY.—IT. 
The normal temperature of the body should be 
maintained at all times, whether the temperature of 
the atmosphere be low or not. This is effected (1) 
by clothing, (2) by the bed, (3) by buildings. 
1. Clothing.—Our garments act like so many ar- 
tificial skins, and thereby protect the skin from the 
injury which would result to it were it left exposed 
to the changing habits of our climate. They lose 
heat in place of the skin ; they sustain intense cold 
or heat, rain and storm, in order that the delicate 
vessel of the skin may not be contracted by cold or 
expanded by heat, and its nerves not be shocked. 
But it is not desirable to shut out the atmosphere 
altogether from the body, else we might wear a 
tight fitting India-rubber suit, or one of kid-leather. 
In either of these the exhalation of the skin (Les- 
son XIII.) would be impeded, which would be fol- 
lowed by dangerous consequences. Besides, close- 
fitting garments are productive of cold, because 
they do not envelop a sufficient quantity of air; 
this may be well shown by wearing kid gloves in 
a cold atmosphere. India-rubber offers excellent RELATION OF AIR TO THE BODY. 
93 
shelter from storm and moisture, but it must not 
form an habitual garment, because it is impervious 
to air. Flannel permits a hundred times as much 
air to pass through its tissues as fine leather, yet 
it is very much warmer than either leather or India- 
rubber. 
The body heats the air around it; the air thus 
heated heats the garments, which should retain 
most of this heated air. The first purpose of cloth- 
ing, therefore, physiologically considered, must be 
to retard the outward diffusion of heat, by radia' 
tion and conduction, from the body. 
Radiation, however, may be prevented by a sin- 
gle cover. This is the case with the earth. In clear 
nights the earth radiates its heat out into space; 
this radiation produces a low temperature on its 
surface, which, under the tropics, becomes fatal to 
travelers sleeping out of doors. In cloudy nights, 
however, the clouds act as a screen; the heat radi- 
ated from the earth is, in great part, reflected back 
to it. 
If, in our latitudes, we wore a single garment, 
though protecting us from the effects of radiation, 
it would he powerless against losses by conduction. 
The outer, colder air, would constantly traverse 
it, cool the layer of heated air around the body, 
strike the skin and there warm itself at the expense 
of the delicate nerves and vessels of the skin. 
The second purpose of clothing, therefore, must 
Ibe to retard the inward motion of currents of outer, 
colder air. FIRST LESSONS IN PHYSIOLOGY. 
94 
From the preceding it is obvious that a regular 
succession of garments is necessary; that they, as 
well as the air which they contain within their 
meshes, grow colder as their distance from the body 
increases ; and that garments generally (more espe- 
cially the outside garments, as an overcoat,) carry 
on upon their surface the equalization of tempera- 
ture between the outer, colder, air and the heated 
atmosphere within, in order that it may not take 
place on the surface of the skin. 
As the garments worn next to the skin are con- 
stantly moistened by perspiration, their water- 
absorbing qualities should be consulted. And 
since moist fabrics are better conductors of heat 
than dry ones, such garments must be frequently 
changed. 
Linen is a rapid absorbent of moisture. As the 
moisture absorbed readily evaporates, and thereby 
produces cold, and as linen is also a good con- 
ductor of heat, it is a favorite article of clothing in 
summer; but it should never be worn next to the 
skin. 
Cotton neither absorbs as much moisture, nor 
conducts heat as well, as linen. It is, therefore, 
warmer, although much cooler than either wool or 
silk. 
Woolen is a great absorbent, which does not give 
np its moisture so readily as the preceding fabrics. 
This property makes it very valuable. It is a 
bad conductor on account of the great quantity of 
air contained within its meshes. It also possesses RELATION OF AIR TO THE BODY. 
95 
the property of condensing water-vapor within its 
tissue, and thus produces warmth. This explains 
why fresh flannel, put on after great exertion, feels 
so warm. It should at all times be worn next to the 
skin. 
2. The bed.—This is the sleeping apparel during 
nearly one-half of our life, and as important as cloth- 
ing. It is made of material similar to that of gar- 
ments and serves the same purpose. But it must 
be made much warmer than our clothing, because 
(1) the body develops less heat during sleep, and 
must yet be maintained at its standard tempera- 
ture ; (2) the body, when not lying down, is heated 
by currents of heated air ascending from the feet to 
the neck, while when stretched out horizontally the 
body is not so heated, for these currents then ascend 
perpendicularly from the body. 
3. Buildings.—Dwelling houses serve the same 
purposes as clothing, which they also resemble in 
this: that, as a rule, they are built of badly conduct- 
ing material. Like clothing, the walls of buildings 
should always be permeable to air. As long as 
they are in good condition they are easily penetrated 
by atmospheric currents. This is evident, for we 
know that wood, brick and stone are more or less por- 
ous, and that they readily absorb water; now, wher- 
ever water can penetrate, air, being so much lighter, 
can enter in hundredfold quantities; the fact that 
we never feel air pass through walls means nothing, 
since currents of air moving at a rate less than 
about 20 inches a second are not felt by the nerves. 96 
FIRST LESSONS IN PHYSIOLOGY. 
Moist walls are unhealthy for the same reasons 
as those applying to moist garments: (1) the stop- 
page of ventilation, the pores of the walls being 
taken up by water to the exclusion of air; (2) the 
cold-producing effects, owing to increased radiation 
and conduction to heat the water; (3) the cold gen- 
erated by the evaporation of the moisture. 
Large quantities of water are contained in the 
mortar of the walls in newly erected buildings. 
Most of this water must be first removed before the 
dwelling is fit to be inhabited. It is removed best 
by giving it sufficient time to evaporate, and pro- 
moting the evaporation by means of artificial heat 
and by removing the vapor by ventilation. 
Pure air is essential to health. Atmospheric 
air depends for its purity on being washed by rain 
and dew. It is heated and dried by the sun, fed 
with oxygen by plants and by them also freed of 
carbonic acid gas. Impure air may result from (1) 
the want of sunlight; (2) the want of cleanliness in 
the household; (3) the absence of efficient ventila- 
tion ; (4) the presence of dust, smoke or decaying 
matter. It is very dangerous to the lungs, and al- 
though its pernicious effects upon the health are 
generally slow, they are nevertheless sure. 
Ventilation and draught may now be better un- 
derstood. Ventilation is the imperceptible efflux of 
impure air and the simultaneous imperceptible in- 
influx of atmospheric air. It depends—(1) Upon the 
difference of temperature between in-doors and out. 
Thus, in severe cold weather, a room, to be well ven- RELATION OF AIR TO THE BODY. 
97 
tilated, must be heated. (2) The quantity of motion 
of the atmospheric air. Strong currents of air, as 
winds or storms, greatly facilitate ventilation. 
(3) The size of the orifices through which the air is 
expected to pass. When No. (1) fails, as e. g., in 
summer, we use No. (3) mostly—that is, we open 
doors and windows. 
Draught is a perceptible current of colder air 
striking, and consequently cooling, only a portion 
of the body. 
Read The Bazar Book of Health (The Dwelling, &c). Harpers. 
Disease Germs. L. S. Beale. Lindsay & Blakiston, Phila. 
Thermic Fever, or Sunstroke. Lippincott, Phila. 98 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXIII.-REYIEW. 
Lesson xxi.— 
1. The human body, in order to properly carry on 
the functions of life, requires a constant internal 
temperature. 
2. A reduction or increase of the standard tem- 
perature may, if continued, prove fatal to life. 
3. A constant temperature of very nearly 100° F., 
whatever be the temperature of the surrounding 
air, is one of the three most important requirements 
of health. (For the other two, see Lessons XIV. and 
XIX.) 
4. This temperature is maintained by interior 
functions of the body. 
5. All bodies continually tend to equalize their 
temperatures by the diffusion of heat. This diffu- 
sion takes place by conduction and radiation. 
6. Whenever substances evaporate or melt, they 
absorb heat; this heat is taken from the adjacent 
body, and this body is thereby chilled. 
7. The human body, as is seen from 5 and 6, loses 
heat in three ways : (1) by conduction, (2) by radia- 
tion, (3) by evaporation. REVIEW. 
99 
Lesson xxii.— 
8. The heat of the body is retained by clothing, 
the bed and buildings. 
9. Clothing protects the delicate vessels and 
nerves of the skin from the effects of intense cold 
or heat. They should include and contain air, be- 
cause air is a bad conductor of either heat or cold. 
10. Clothing (1) retards the outward diffusion of 
heat (by radiation and conduction) from the body ; 
(2) it retards the inward motion of currents of outer 
colder air. 
11. The bed must be warmer than one’s garments, 
because (1) the body develops less heat during 
sleep, and must yet maintain its standard tempera- 
ture; (2) the body, when in a horizontal position, 
is not heated by currents of heated air ascending 
along it. 
12. The walls of buildings should be permeable 
to air, the same as clothing. 
13. Moist walls are pernicious to health, because 
(1) of the stoppage of ventilation, the pores of the 
walls being taken up by water to the exclusion of 
air; (2) of the cold-producing effects, owing to in- 
creased radiation and conduction to heat the water; 
(3) of the cold generated by the evaporation of the 
moisture. 
14. The moisture in the walls of newly erected 
buildings is best removed by giving it sufficient 
time to evaporate, by promoting its evaporation by 100 
FIRST LESSONS IN PHYSIOLOGY. 
means of artificial heat, and by removing the water- 
vapor by ventilation. 
15. Pure air is essential to health. Our atmos- 
phere is washed by rain and dew. It is heated 
and dried by the sun ; it is fed with oxygen by 
plants, and freed by them of carbonic acid gas. 
16. Impure air may result (1) from the want of 
sunlight; (2) the want of cleanliness in the house- 
hold; (3) the absence of efficient ventilation; (4) 
the presence of dust, smoke, or decaying matter. 
17. Ventilation is the imperceptible efflux of im- 
pure air, and the simultaneous imperceptible influx 
of atmospheric air. 
18. Draught is a perceptible current of colder air 
striking only a portion of the body. FOOD. 
101 
LESSON XXIV. 
FOOD. 
11. Experiment.—Hydrogen gas may be liberated from muriatic acid 
poured on a little zinc or on a nail in a test-tube. The gas is recognized 
by its burning with a pale, bluish flame. By connecting the mouth of the 
test-tube with a suitable tube, the gas may be conducted into a tumbler fill- 
ed with and inverted over water. 
12. Experiment.— Oxygen gas may be liberated from an ounce of pul- 
verized potassium-chlorate mixed with a like quantity of manganese di- 
oxide, by placing the mixture in a test-tube and applying heat. It may be 
recognized by its rekindling a glowing taper ; like hydrogen, it is easily 
caught in an inverted tumbler. 
13. Experiment.—Nitrogen gas may be obtained from common air by 
burning a short piece of candle, fastened on a fragment of board so as to 
float on water, and inverting a glass jar over the candle. The light will be 
extinguished, some water will rise into the jar, and nearly all the remain- 
ing gas will be nitrogen. 
Carbon may be represented by a piece of coke or charcoal. 
Hydrogen, oxygen, nitrogen—three gases—and 
cartoon—a solid—are the principal elementary sub- 
stances which, when combined with each other, form 
the materials composing the human body. 
The functions of the human system cause a waste 
of tissues. This waste must be repaired or the in- 
dividual will die. Since the human body is com- 
posed of combinations of carbon, hydrogen, oxygen 
and nitrogen, it must be repaired by a supply of 
aliments containing these materials. When an or- FIRST LESSOJNS IN PHYSIOLOGY. 
102 
ganism is deprived of proper food it commences to 
feed upon itself. 
Waste of tissue arises from the incessant work 
which the body performs, consisting of mechanical 
motion, as when a person is walking, or a black- 
smith strikes a piece of iron on the anvil; or of vi- 
tal functions, such as breathing and digesting; or 
of mental processes, as when one is thinking and 
studying. All such work diminishes the weight of 
the organism ; and if the labor were continued with- 
out food being taken to repair the waste, the result 
would be death. For a further illustration, sup- 
pose that a man who has been carefully weighed, 
be placed in a glass house containing cold and dry 
atmospheric air, and told to walk up and down in it 
for an hour without interruption. At the end of 
that hour, if he be weighed again, he will be found 
to have lost in weight. This loss is balanced by the 
amount of work he has done, viz.: 1. The mechan- 
ical labor in lifting and moving the weight of his 
body at every step. 2. The rise in temperature, in- 
dicated by a thermometer hung up inside of the 
glass house, which shows that he has heated the 
air around him. 3. The moisture on the inner sides 
of the glass, due to expiration. 4. Carbonic acid 
gas, also due to expiration, the presence of which is 
shown by a white film of carbonate of lime on the 
limewater in a vessel placed on the floor of the 
glass house. 
Food, generally speaking, is any substance adapt- 
ed to supply the body with material that renews 
lost tissue or supports some process of life. It FOOD. 
103 
is divided into organic and inorganic materials. 
Organic food comprises (1) nitrogenous substances, 
such as meat, milk, or white of an egg; (2) fats, such 
as butter or lard; (3) compounds of carbon and 
hydrogen, such as starch or sugar. The last two 
classes, when pure, contain no nitrogen. Inorganic 
food comprises water, the most important article of 
food, and alkalies, such as salt and phosphates. ~No 
single class is generally considered sufficient; all 
of them are necessary to make food nutritive and 
convenient; a man feeding entirely upon bread and 
sugar may ultimately be starved as surely as one 
whose diet is composed solely of meat, or of mineral 
water. Intuitively, we eat bread and meat, or bread 
and cheese, bacon and beans, stuffing and fowl. 
Persons who live largely on meat prefer it fat; those 
who feed mostly on vegetables consume a great deal 
of milk, because milk contains the three classes of 
organic food, as well as inorganic materials. 
Oxygen is an article of food, as it serves to main- 
tain important vital functions. It is the only article 
of food which enters the system as a simple or 
elementary body; all the others are compounds. 
Digestibility of Food.—A substance may be 
highly nutritious, but if its consistency is so great 
that it is insoluble in the digestive fluids, it is use- 
less as nourishment. This is the case with bones 
and cartilages. Tasteless substances, such as com- 
mon oil, do not digest, because they fail to pro- 
duce secretion of saliva, an essential element in the 
preparation of food. Many articles of food are ren- 104 
FIRST LESSORS IN PHYSIOLOGY. 
dered nutritious by condiments, which, without 
these, might not even have been palatable. Tea, 
coffee and j uices must be regarded as great helpers 
to nutrition; so also a frequent change of, and 
variety in, our bill of fare. 
Irregularity in diet is a frequent cause of disease. 
Next to it, perhaps, stands the want of the proper 
preparation of food by cooking. The purpose of 
cooking is : (1) to soften the food; (2) to give it an 
agreeable favor. Beans, grains and many kinds of 
fruit can not be digested in a raw state. 
Hunger and Thirst.—The man whom we sup- 
posed to take exercise in a glass-house would dwin- 
dle to nothing in due course of time unless he 
took food to repair his waste. The imperious sen- 
sations which remind us forcibly of the want of 
solid and liquid aliment are hunger and thirst. To 
satisfy the former, the body must be supplied with 
solid food; to satisfy the latter, with water in some 
shape or other. 
Solid Food.—Over the whole world beef is justly considered the most 
nutritious kind of flesh. Its flavor is fuller and more attractive than that 
of other meats, and, as it has a denser structure, the volume of beef re- 
quired for a meal need not be as large as that of other kinds of flesh. Veal 
is inferior to beef, as it is more difficult to digest. Mutton, although a 
lighter food than beef, is more suited to persons who take little exer- 
cise. Pork is less nourishing than either beef or mutton. It is commonly 
believed to be less digestible, and scientists have found that it requires more 
time for digestion. Ham is more nearly like beef, as it contains less fat 
than the other parts of the pig. Pork is known to be more frequently 
diseased than other meats. Its use is most extensive in new coun- 
tries on account of the facility in raising pigs, in preserving the meat, 
and also on account of the difficulty in having a sufficient demand in thinly- 
settled districts for a freshly-slaughtered ox or sheep. Fish should never FOOD. 
105 
take the place of beef permanently, but rather play the part of an agreeable 
companion to, or variety of, other animal food. The nutritive qualities of 
red-blood fish, as the salmon, are nearly as great as those of any other red- 
blood flesh, while white fish is less nutritive. Butter depends for its flavor 
very much upon the food of the animal from which it is derived. As lean 
meat serves principally to produce and maintain the structures of the body, 
the fats—and they include butter—mainly generate by their oxidation the 
heat required for the vital processes. 
Wheaten floitrand bread are “ the most important vegetable production of 
temperate climates — that upon which the life of man in these regions 
mainly depends. Its importance rests upon several properties, by which 
it is acceptable and good food for all ages and classes of the people. It is 
produced abundantly and cheaply ; is easily ground and refined; is readily 
and thoroughly cooked; has a mild flavor which is universally agreeable, 
and contains nearly all the essential elements of nutrition. It is preferable 
to any of the other great vegetable products on which men chiefly live, 
since it is a far more agreeable food than maize, and a more nutritious food 
than rice. It is probable that the health and mental and bodily vigor of 
the inhabitants of temperate climes are more attributable to this food than 
to any other single cause.” Potatoes can not be used alone, as they lack 
mineral elements; about three pounds of potatoes are equivalent to one 
pound of bread as regards nutritive contents. 
Liquid Food. — Water is, of all foods, whether liquid, solid or gaseous, 
the most important. It forms about 87 per cent, of the human body. 
Lean beef contains nearly 72 per cent, of water, veal 63, mutton 72, fat 
pork 40, poultry 73, fish 75, wheaten bread 37, coffee and tea nearly 100. 
To be good to the taste it must contain, as it nearly always does, a small 
quantity of atmospheric air. Mineral matters in water render it hard; for 
domestic purposes it is rendered soft by boiling, or by treatment with lime, 
soda or ammonia. Organic matter in water is harmless when existing 
in very minute quantities; if otherwise, it is very injurious to the system 
and a frequent source of disease. Turbid water from wells is impure, 
while the turbidity of water from streams simply arising from sand or the 
soil is quite harmless. Water infected with organic matter, or offensive 
to the smell or taste, must be rejected. Milk contains all the nutritive 
elements, and is readily digested. Tea is an infusion of the leaves of the 
tea-plant, of scarcely any nutritive quality, but highly valued as a means of 
exciting vital processes and stimulating respiration as well as perspiration. 
Coffee is probably as little nutritious as tea; like this, it stimulates respira- 
tion, but, unlike tea, it tends to make the skin dry. 106 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XX Y. 
DIGESTION.—I. 
[Before studying this Lesson review “Teeth,” Lesson III.] 
The food of plants requires no modification pre- 
vious to its being absorbed by the vegetable organ- 
ism. Plants feed principally on water, carbonic 
acid, ammonia, and saline substances, all of which 
they find ready for their absorption. Man and ani- 
mals, however, derive their food principally from 
organic substances. They prepare it within their 
bodies before it is absorbed by the blood; and man, 
in addition, cooks his food. 
The changes wrought upon the food in the body 
may be divided into three parts: 1. Digestion, or 
the proper preparation of food in the alimentary 
canal (Lesson III.), so as to fit it for absorption. 
2. Assimilation, or the conversion of food into blood 
and tissue. 3. Excretion, or the decomposition of 
food and its removal from the body. With the ex- 
ception of the lungs, which absorb oxygen, the ali- 
mentary canal is (generally) the only channel by 
which food can pass into the blood. 
The quantity of food—dry, solid and nutritions— 
daily introduced into the mouth of a man of aver- 
age size and activity, is about 35 ounces, to which 
must be added about a pound of oxygen gas ab- 
sorbed by the lungs, making in all a little over DIGESTION. 
107 
three pounds. To this should be added the oxygen 
which, during insalivation, mingles with the food. 
Digestion commences immediately upon the pass- 
age of food into the mouth before entering the 
stomach. Solid food must first be 
crushed by the action of the teeth, 
jaws and tongue. This part of di- 
gestion is called Mastication.. 
While the structure of teeth be- 
longs to Lesson III., it may be inter- 
esting here to refer to the adapta- 
tion of teeth in different classes of 
animals to the food upon which the animal sub- 
sists. Thus, in fish, the food is swallowed entire; 
hence, the teeth have, as a rule, the form of sharp, 
curved spines (Fig. 22). Such teeth merely serve the 
purpose of retaining or holding the prey. The 
Fiy.22 
Jaws of aFiah. 
Fiff.23. 
Skull of a Horse. 
horse has incisors in both jaws (Fig. 23), while her- 
bivorous animals of the ruminating order have their 108 
FIRST LESSON'S IN' PHYSIOLOGY. 
incisors only in the lower jaw. These incisors 
merely serve to cut off the grass or herbs upon 
which the animal feeds. The process of mastica- 
tion is performed entirely by the molars, the canines 
being either wanting or only imperfectly developed. 
Carnivorous animals, such as the bear or dog, have 
incisors for dividing the food, canine teeth for at- 
tacking and retaining the prey, and molars for 
grinding (Fig. 24). In man the teeth are so selected 
as to combine the features of those of the herbivor- 
ous and the carnivorous animals, which distinctly 
points to the fact that his food should be composed 
both of animal and vegetable substances. The 
tongue has the function of holding back the por- 
tion of aliment which is about to pass down not yet 
wholly crushed by the teeth; and any particles of 
food which have been pushed outside of the teeth 
are thrust back again under the teeth by the com- 
pression of the lips and cheeks. The tongue also 
crushes soft substances against the palate. It is, at 
the same time, an organ invested with special mo- 
bility and acute sensibility, so as to pass judg- 
ment upon the qualities, situation and degree of 
trituration of the aliment in the mouth. The com- 
bined action of the teeth, tongue, lips and cheeks 
results in the breaking down of the food. The pur- 
pose of this is, that the food shall present a large 
surface to the dissolving action of the various 
fluids acting upon it. If large masses were to pass 
down unbroken by the teeth, they would scarcely 
be altered in the stomach, and supply 
nutrition imperfectly. For this and other reasons, DIGESTION. 
109 
rapid eating should he studiously avoided; it fre- 
quently causes indigestion. 
Insalivation, the second part of digestion, takes 
-place in the month. It is here that the masticated 
food thoroughly mixes 
with the saliva of the 
mouth, abundantly se- 
creted from a number 
of salivary glands, and, 
at the same time, min- 
gles with air, which is 
contained in the bub- 
bles of the saliva. This 
liquid contains over 990 
parts of water in 1,000 
parts of its weight. It 
changes a large portion of the starch, which the 
food may contain, into sugar. 
Fig.24^. 
Skull of a Polar Bear. 
Deglutition, or the act of swallowing—the third 
part of digestion—takes place after the aliment, by 
means of mastication and insalivation, has been re- 
duced to a minute pulp, and transferred from the 
mouth through the oesophagus or gullet, to the 
stomach. This downward passage is effected by a 
successive contraction of the muscular parts around 
the oesophagus above the food, while they are lax 
below. Hence it is that a man can drink standing 
on his head; and a horse with its head lower than 
its stomach. Food, while in the mouth, is controll- 
ed by the will, but deglutition is not. 110 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXVI. 
DIGESTION.—II. 
Digestion in the stomach is the fourth part of di- 
gestion. The stomach (Fig. 25, p. 114) is the con- 
tinuation of the gullet, hut it is much wider, and of 
different forms in different animals. It is a sort of 
hag of about one and a quarter square feet internal 
surface, with a capacity of five pints, and a weight 
of seven ounces, in the adult man. It has two open- 
ings—one (a) to admit food, called Cardia, and 
which is always open ; the other (5), called Pylorus, 
which, during stomach digestion, is firmly closed so 
as to allow only the finest pulp to pass. On the 
outside the hag consists of a thin membrane, next 
to which is a muscular coat, forming the center; and 
of a mucous layer, which forms the inner lining of 
the substance of the bag. The muscular coat is 
made up of involuntary muscles; it is these which 
perform the mechanical labor of kneading and roll- 
ing about the pulp. The food is pushed on along 
the great curvature of the stomach (on the left side 
of the body) to the right, and thence to the left along 
the lesser curvature. The continual rolling motion, 
together with the continual addition of gastric j uice, 
finally reduces the food to a fine pulp of a consis- 
tency somewhat like that of a thick soup, which is 
called chyme. The stomach is not capable of great DIGESTION. 
muscular effort; hence, it can not crush, e. g. an 
entire grape. The violence of abdominal motion in 
vomiting is not due to the effort of the stomach 
alone, but to the co-operation of abdominal muscles. 
Chief functions of the stomach: (1) to mix all 
food into a pulp; (2) to dissolve the nitrogenous 
portion of the food by means of the gastric juice 
(see next Lesson). The conversion of starch into 
sugar, which takes place in the mouth, is in the 
stomach discontinued temporarily, but not sus- 
pended, as will be seen further on. (Regarding 
absorption in the stomach, see the next Lesson.) 
Conditions favorable to stomach digestion. The 
following are among the most important: 1. A tem- 
perature of 100° F., nearly. Any reduction, such as 
results from overdoses of water or ice cream, may 
lead to serious results. When a substance, instead 
of being digested in the stomach, is digested in the 
intestines, the time required is vastly greater. 
2. Continual motion of the walls of the stomach 
to permeate the food with gastric juice. 
3. The removal of such portions of the food as 
are thoroughly digested. This brings the remainder 
into better contact with the gastric fluid. 
4. Perfect mastication and insalivation of the ali- 
ment previous to its entrance into the stomach. 
5. A moderate quantity of food. The stomach 
should not be distended. 
6. Regular intervals between any two consecutive 
meals. They should be long enough for the food of 
one meal to have left the stomach before the next is 
introduced. 112 
FIRST LESSONS IN PHYSIOLOGY. 
7. No severe physical or mental exertion either 
immediately before or after a meal. 
8. A tranquil mind. 9. Bodily health. 
10. Favorable weather. 
The processes which the food has undergone be- 
tween its first introduction into the mouth and its 
removal from the stomach through the pylorus are : 
(1) mastication, (2) insalivation, (3) deglutition, (4) 
digestion in the stomach. 
The changes wrought upon the food by these pro- 
cesses should now be carefully reviewed. What 
happens to the food in the stomach will be ex- 
plained in the next Lesson. 
“ According to the experiments of Dr. Beaumont, liquid substances are, 
for the most part, absorbed by the vessels of the stomach at once, and any 
solid matter suspended in them, as in soup, are concentrated into a thicker 
material before the gastric juice operates upon them. Solid matters are 
affected so rapidly during health that a full meal, consisting of animal and 
vegetable substances, may be converted into chyme in about an hour, and 
the stomach left empty in two hours and a half. Dr. B. found that among 
the substances most quickly digested were rice and tripe, both of which were 
digested in an hour. Eggs, salmon, trout and venison were digested in an 
hour and a half; tapioca, barley, milk, liver and fish in two hours; tur- 
key, lamb and pork in two hours and a half. Beef, mutton and fowls re- 
quired from three to three and a half hours, and these were more digesti- 
ble than veal. These facts were different from what was anticipated, and 
show that prevailing notions as to the digestibility of different kinds of food 
are very erroneous. It must be remembered, however, that easy digesti- 
bility does not imply high nutritive power. A substance may be nutritious, 
though so hard as not to be readily broken down ; and many soft, easily 
digested materials may contain a comparatively small amount of nutri- 
ment.”—J. H. Bennett. Physiology. Lippincott & Co., Phila. 
Read Dyspepsia. By E. P. Miller. Miller, Haynes & Co., N. Y. DIGESTION. 
113 
LESSON XXYII. 
DIGESTION.—III. 
Digestion in the intestines—the fifth part of the 
process of digestion. The intestines (Fig. 25) are 
the continuation of the stomach. They form a long, 
narrow tube, which, like the stomach, is composed 
of membranous, muscular and mucous coats. The 
intestines are of different length in different orders 
of animals. They are divided into two parts, viz., 
the small intestine and the large intestine. 
The small intestine is subdivided into the duode- 
num, D, and the small intestine proper, Dp. The 
order in which they follow each other is, (1) the 
stomach, (2) the duodenum, (3) the small intestine 
proper, (4) the large intestine. 
The alimentary canal begins with the mouth and 
terminates with the rectum. Its entire length is 400 
inches, nearly, of which about 240 inches belong to 
the small intestine. The small intestine has many 
windings, is indirectly attached to the spinal col- 
umn, and fills the lower central portion of the ven- 
tral cavity. 
The small intestine possesses a regular motion in 
the direction of its own course; this motion is call- 
ed 'peristaltic, and consists of muscular contrac- 
tions, such as take place in the gullet, the purpose of 114 
FIRST LESSONS IN PHYSIOLOGY. 
Fig. 25.—The Digestive Appara- 
tus (Henle, Anat). 
Front \ iew—Head and Neck 
turned toward the right. 
T Trachea, t Left Liver cut off. 
g Gullet. C Caecum. 
a Cardia. va Vermif. Appen. 
S Stomach. Co Colon. 
b Pylorus. R Rectum. 
P Pancreas. L Liver. 
D Duodenum. 1 Gall Bladder. 
Dp Sm. Intest. 2 Diaphragm, 
pro., laid aside, sp Spleen. DIGESTION. 
115 
which is, to propel the food onward to the lower 
parts and into the large intestine. 
The large intestine, about five feet long, is shorter 
but wider than the small intestine. It has three 
subdivisions: the caecum, C, the colon, Co, and the 
rectum, R. The cmcum is the short portion below 
the junction of the small intestine, and distinguish' 
able by a vermiform appendix, v, a, about three 
inches in length. The continuation of the caecum 
forms the colon, which rises on the right side of the 
abdomen up to the liver. This portion of it is 
the ascending colon. The colon then suddenly turns 
at a right angle and crosses over to the left side of 
the body; this horizontal part of it is called the 
transverse colon; finally, it makes a sudden turn 
downward and backward along the left side of the 
body, where, accordingly, it is called the descend- 
ing colon, which is succeeded by the rectum, R. The 
large intestine is readily recognized by its width, its. 
stretching capacity and its many folds and pouches. 
Its motions are far slower than those of the other 
intestine, and scarcely ever result in actual dis- 
placements of the parts with reference to each other, 
such as take place in the small intestine. 
DIGESTIVE FLUIDS. 
1. The saliva, the action of which was explained 
on page 109. 
2. The gastric juice. The interior coat of the 
stomach contains a great number of glands which 
are open upon its surface. Some of these are in the 116 
FIRST IN PHYSIOLOGY. 
vicinity of the pylorus, and secrete a mucous sub- 
stance which covers the interior surface of the 
stomach, and serves to envelop undigested pieces 
of food so as to facilitate their passage through the 
intestines. The others, which form by far the greater 
number, secrete a clear acid liquid, the gastric juice. 
This fluid has an extraordinary solvent power on 
albuminous and other substances ; one part of it in 
60,000 parts of water will be sufficient to exert this 
power. It does not act upon fatty substances fur- 
ther than liquefying them. It is readily precipitated 
by alcohol; this may explain the pernicious effect 
upon the stomach, caused by the use of alcoholic 
drinks. The churning motion of the stomach, to- 
gether with the solvent action of the gastric juice, 
reduces the food to chyme, which passes through the 
pylorus into the duodenum, and is shortly after- 
ward mixed with bile and pancreatic juice. The 
stomach is the part in which the food undergoes 
its most important change. 
3. The Bile is a brownish-yellow, very bitter 
liquid secreted by the liver (L, Fig. 25). The liver 
is the largest gland in the body ; it weighs from 50 
to 60 ounces, has a dark-red color, and lies on the 
right side of the body. Its upper part is connected 
with the diaphragm, its lower touches the intes- 
tines. The liver (1) secretes bile, and (2) modifies 
sugar for purposes which this has to serve. The 
bile accumulates in a reservoir, called the gall-blad- 
der, from which, whenever the duodenum is dis- 
tended by chyme coming from the stomach, it flows 
into the duodenum, to mingle with the chyme. Bile DIGESTION". 
117 
contains waste materials which it has taken from 
the blood; it must, therefore, be conducted out of 
the system. If prevented from entering the duode- 
num, it congregates in the blood, producing jaun- 
dice, and acting then as a poison. Should some of 
it happen to be thrown into the stomach, digestion 
there would cease at once; nausea and vomiting, the 
usual bilious symptoms, would occur. It acts also 
as a solvent of the fatty portions of food, and as a 
stimulant to the action of the intestines. Chyme, 
after its union with bile, is usually called chyle. 
Chyme, as it leaves the stomach, is composed of— 
(1) Albuminous matter, broken down, partly dis- 
solved, partly dissolving, and, it may be, partly un- 
dissolved. 
(2) Fatty matter, broken down, but not dissolved. 
(3) Starch, being slowly converted into sugar, and 
as fast as it becomes sugar, dissolving in the fluids 
of the mixture. 
(4) Gastric juice, mixed with substances 1, 2, 3, 
and liquids, and such portions of aliment as are 
undigestible. 
4. The Pancreatic Juice is a clear, colorless 
liquid, distinguished (1) by its great capacity for 
digesting fats after they have become fluid by the 
warmth of the stomach; (2) by its dissolving albu- 
minous substances. It is secreted from a gland, P, 
about seven inches long, having the form of a 
bunch of grapes, and generally resembling the sali- 
vary glands of the mouth. This juice also enters 
the duodenum. The salivary glands and the pan- 
creas are readily influenced by the nervous system; 118 
FIRST LESSORS IN PHYSIOLOGY. 
thus, the sight, or smell, or the mere thought of 
food may prompt the salivary glands to pour saliva 
into the mouth, or, in common language, cause 
“ the mouth to water.” 
5. The Intestinal Juice, a thin fluid, is secreted 
from minute glands on the interior surface of the 
small intestine; its business seems to be to digest 
albuminous matter which has escaped the action of 
the gastric juice. The main office of the small in- 
testine is to digest fat. Intestinal juice is also se- 
creted from the colon. 
The quantity of these five liquids generated daily 
has been estimated at 22 pounds, nearly, of which 
that of the gastric juice amounts to about 14 
pounds. It is plain that their office is to dissolve 
the food and act chemically upon it. Each of them 
seems to have its special function, and yet none is 
exclusively directed to one object. They all aid 
each other, and are in turn assisted by the peristal- 
tic motion of the intestines, which thoroughly 
mixes the food with them, and propels the chyle 
from above downward through that portion of the 
alimentary tube which succeeds the stomach. The 
undigested masses collect in the rectum to be prop- 
erly removed. 
Read Constip. of Bowels. By S. B. Birch. Lindsay & Blakiston, Phila. ASSIMILATION. 
119 
LESSON XXVIII. 
ASSIMILATION. 
Chyme and chyle are merely digested food. Both 
are in the alimentary tube; one is in the stomach, 
the other in the intestines. As yet they are stran- 
gers to the system—that is to say, they do not form 
part of it. 
The oxygen of the air which enters the lungs rap- 
idly burns up the particles of waste tissue which 
are thrown into the lungs by the venous blood. 
How, this waste matter must be replaced by fresh 
particles, else the vital processes speedily cease. 
In other words, at every instant of life a quantity 
of animal tissue is dying, and must at the next in- 
stant be replaced. If no freshly-digested food is at 
hand, as during disease, the burnt up particles of 
the body are replaced, first, by the fat of the tis- 
sues, and hence the sunken appearance of the eyes 
and cheeks; or next, by the flesh of the tissues 
themselves, which results in emaciation, and fin- 
ally in death, unless cure can be effected. Thus, 
death and life are intimately associated and depen- 
dent upon each other in the living organism. 
The question now arises: How is the digested ali- 
ment converted into blood so as to be distributed in 
this form over the entire body, and to replace waste 
matter—in fact, to furnish the material for the 120 
FIRST LESSONS IN PHYSIOLOGY. 
growth and maintenance of the body ? The answer 
is : The chyle throughout the course of the ali- 
mentary canal is taken up by capillaries and 
special minute vessels, called chyle-vessels or lac- 
teals, and conveyed into the circulation at large. 
With the aid of respiration, it is then made into 
nourishing blood. The process of taking up the 
chyle forms part of the process of absorption. 
Absorption.—The object of this process is, (1) to 
supply the blood with fresh materials; (2) to re- 
move such particles as have accomplished their 
mission in the body. Absorption, then, has a two- 
fold character; it absorbs essentials from without 
the body and carries them to the blood; it absorbs 
waste materials from within the system and con- 
veys them outside the body. Absorption is mainly 
carried on by two distinct sets of vessels, viz., blood 
vessels or capillaries, and lacteals or lymphatics, al- 
so called absorbents. The former are abundantly 
spread over the interior surface of the stomach, and 
both the small and large intestines ; the latter only 
in the intestinal canal, but most numerously in the 
small intestine. Both sets of vessels form a perfect 
network, completely covering the interior surface of 
the intestinal canal; in the small intestine this net- 
work is closer to the chyle than anywhere else. 
Absorption by Blood Vessels.—The minute blood- 
vessels and capillaries in the mucous coat of the 
stomach and intestines (Fig. 26) absorb at b and c 
completely digested aliment; this substance is so 
finely divided as to readily pass through the walls 
of the blood-vessels in the manner, roughly speak- ASSIMILATION. 
121 
ing, of water passing through (from without to the 
interior of) the walls of a hollow tube made of 
blotting-paper. The blood at A is arterial; on its 
passage through the capillaries, b and c, it absorbs 
chyle (together with waste materials), which renders 
it venous; through a it descends into vein Y, to 
be ultimately conveyed to the lungs. The blood- 
vessels are not very particular in the choice of fluid 
particles ; they absorb nearly all kinds except the 
fatty portions. Water, and similar beverages, are 
believed to be absorbed by the blood-vessels of the 
stomach without passing into the duodenum. 
Fig.26 
Transverse Section of Mucous Membrane of Colon. 
A Artery. V Vein, a a Descending Veins. bb Venous Net on 
Inner Surface, c Capillaries in Mucous Membrane. 
Absorption by the Lacteals is carried on in the 
same manner. It is rendered most effective in the 
small intestine, because the interior wall of this intes- 
tine presents a larger surface to the chyle as it passes 122 
FIRST LESSONS IN PHYSIOLOGY. 
by. This greater extent of surface is owing to the 
fact that the mucous membrane which forms the 
interior surface, is folded into a great abundance of 
Fig. 2 7. 
Transverse Section of the Duodenum of a Calf. 
1 Villi. 2 Interior Chyle-Vessels. 3 Glands. 4 Exterior Chyle-Vessels 
or Lacteals. 5 6 Muscular Coat. * Valvular Chyle-Duct. 7 Skin. 
conical projections, called villi (Fig. 27, 1), some- 
what resembling the velvety projections of a Turk- ASSIMILATION. 
123 
ish towel. From the villi the absorbed materials 
pass through the interior chyle vessels, 2, and 
through glands, 3, to the exterior chyle-vessels or 
lacteals, 4. These vessels gradually increase in 
size, and on leaving the intestine obtain the valvu- 
lar structure of veins. This prevents any absorbed 
chyle from flowing back to the villi. The way in 
which each villus imbibes the chyle is explained 
thus: the villi have minute muscles which cause 
them alternately to contract and expand; at every 
expansion each villus fills with chyle; at every con- 
traction it squeezes its contents into the lymphatic 
vessels beyond. The villi may be compared to the 
delicate root-fibres of plants, which are spread in 
the ground for the purpose of absorbing food for 
the plant; like the villi, these vegetable fibers are 
without openings, and yet, as is known from the 
fact that drooping leaves revive again after a shower 
on a hot day, they are capable of absorption. The 
special function of the villi seems to be the absorp- 
tion of the fatty portion of the chyle, although they 
absorb also other materials. The villi are found 
only in the small intestine. 
The lymphatic glands receive the chyle from the 
lymphatic or chyle-vessels (Fig. 27, *) mentioned 
above. The largest of these glands is the spleen 
(Fig. 25), situated on the left side of the abdomen. 
The lymphatic glands are widely distributed in the 
body. The chyle on passing through them under- 
goes some change, and on leaving them it flows into 
the thoracic duct. 
The thoracic duct (Fig. 28) is a tube of the width 124 
FIRST LESSONS IN PHYSIOLOGY. 
of a goose quill, nearly, which receives the chyle of 
the lymphatic vessels and glands, and empties it 
into a vein on the left side of the chest, near the 
heart. A similar, smaller tube, likewise throws its 
contents into a vein on 
the right side of the 
chest, near the heart. 
Thus, the lymphatic ves- 
sels are the carriers of 
the chyle on its way to 
the blood; they act like 
veins in this, that they 
contain valves to make 
their contents flow in one 
direction only; with one 
end they terminate in 
two ducts, which open 
into the large veins and 
finally into the heart; 
at the other end they 
terminate in microscopic 
branches or lymph-cap- 
illaries, which are dis- 
tributed throughout the 
tissues of the body. The 
villi form part of these 
lymph-capillaries. The 
lymphatic vessels of the 
intestinal canal pass by 
the name of lacteals, because their contents resem- 
ble milk in appearance; there is no difference be- 
tween lacteals and lymphatics. It should be borne 
Fiit. 28 
The Thoracic Duct. ASSIMILATION. 
125 
in mind that there are blood-vessels and capillaries 
within each villus as well as around the villi, which, 
as before mentioned, carry on absorption. 
From the preceding it is evident that man and 
the higher vertebrates have, in addition to the intri- 
cate system of arteries and veins, another system 
of vessels, called the lymphatic system. This con- 
tains a fluid called lymph, which is chyle altered 
by the lymphatic glands. As the blood-vessels 
have blood capillaries, so the lymphatic-vessels 
have lymph-capillaries near the skin; these widen 
into lymph-vessels toward the interior of the body. 
Read Science Lectures. First Series. Heywood : Manchester. 126 
EIRST LESSONS IN PHYSIOLOGY. 
LESSON X XIX. — REVIEW. 
Lesson xxiy. 
1. The human body is composed largely of com- 
binations of carbon, nitrogen, hydrogen and oxy- 
gen ; hence our food must contain these elements. 
2. Waste of tissues is due to the incessant work 
performed b}r the body ; most of this work consists, 
during life, of (1) the mechanical labor in lifting 
and moving the body; (2) the maintenance of the 
standard of temperature; (3) secretion of moisture 
and carbonic acid. 
8. Food may be called any substance adapted to 
supply the body with material that renews lost tis- 
sue or supports some process of life. 
4. Food consists of organic and inorganic mate- 
rials. 
5. Organic food comprises (1) nitrogenous sub- 
stances ; (2) fats; (8) compounds of carbon and hy- 
drogen, such as sugar or starch. 
6. Inorganic food comprises water, and alkalies, 
such as salt and phosphates. 
7. Substances of too great consistency, or such as 
are tasteless, are indigestible. 
8. The purposes of cooking food are too soften it 
and to give it an agreeable flavor. REVIEW. 
127 
Lesson xxv.— 
9. The changes wrought upon the food in the 
body are (1) digestion, or the proper preparation of 
food in the alimentary canal; (2) assimilation, or 
the conversion of food into blood and tissues; (3) 
excretion, or the decomposition of food. 
10. Digestion comprises (1) mastication, (2) in- 
salivation, (3) deglutition, (4) stomach-digestion, (5) 
digestion in the intestines. 
11. The chief functions of the stomach are (1) to 
mix the food into a pulp ; (2) to dissolve the nitro- 
genous portion of the food by means of the gastric 
juice. 
12. The chief conditions favorable to stomach- 
digestion are (1) a temperature of 100° F., nearly; 
(2) continual motion of the walls of the stomach; 
(3) the removal of thoroughly digested portions of 
food from the stomach; (4) previous perfect masti- 
cation and insalivation of the food; (5) a moderate 
quantity of food; (6) regular intervals between 
meals ; (7) no severe physical or mental exertion 
immediately before or after a meal; (8) a tranquil 
mind ; (9) bodily health ; (10) favorable weather. 
13. The processes undergone by the food between 
its first introduction into the mouth and its removal 
from the stomach through the pylorus are (1) mas- 
tication, (2) insalivation, (3) deglutition, (4) diges- 
tion in the stomach. 128 
FIRST LESSONS IN PHYSIOLOGY. 
Lesson xxvi.— 
14. The part of the alimentary canal succeeding 
the stomach is the intestines. They are divided 
into the small and the large intestine. 
15. The small intestine comprises the duodenum, 
and the small intestine proper. 
16. The large intestine comprises the caecum, co- 
lon, and rectum. 
17. The small intestine has peristaltic motion. 
18. The digestive fluids are (1) the saliva, (2) the 
gastric juice, (3) the bile, (4) the pancreatic juice, 
(5) the intestinal juice. 
19. Functions of the saliva : 
(1) Softening the food ; 
(2) Converting starch into sugar ; 
(3) Mingling the food with air. 
Function of the gastric juice: Dissolving al- 
buminous and other substances. 
Functions of the bile: 
(1) Absorbing waste material from the 
blood; 
(2) Dissolving fatty portions of the food • 
(3) Stimulating the action of the intestines. 
Functions of the pancreatic juice : 
(1) Digesting fats; 
(2) Dissolving albuminous substances. 
Function of the intestinal juice (probably): 
Digesting albuminous matter. 
20 The food undergoes its most important 
change in the stomach. When leaving the stomach 
it is called chyme. REVIEW. 
129 
21. Chyme is composed of (1) albuminous matter, 
(2) fatty matter, (3) starch, (4) gastric juice. 
22. After its union with bile, chyme is usually 
called chyle. 
23. The object of absorption is (1) to supply the 
blood with fresh materials ; (2) to remove waste 
particles. 
24. Absorption is effected by blood-vessels (capil- 
laries), and by lacteals (or lymphatics). 
25. Absorption by blood-vessels takes place 
chiefly in the stomach and the intestinal canal. 
The so absorbed materials are conveyed to veins. 
26. Absorption by lacteals takes place in the 
small intestine by minute vessels called villi; these 
lead the absorbed chyle into the lacteals or lymph- 
atic vessels, whence it is conveyed through the 
lymphatic glands to the thoracic duct, and thence 
thrown into veins. 
27. The lymphatic system of the body has its 
ramifications throughout the body similar to the 
system of blood-vessels, from which it differs in this, 
that its fluid is lymph, and flows in only one direc- 
tion. 
28. By the aid of respiration, the chyle is finally 
made into blood. 
29. The want either of proper food or of proper 
digestion destroys one of the three most essential 
requirements for health, viz., the proper composi- 
tion of the blood. FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXX. 
THE NERVOUS SYSTEM — I. THE DIFFERENT PARTS. 
General Remarks.—We have become acquainted 
with the various bones and tissues which compose 
the structure of the body; with some of the mus- 
cles which more the body; with the alimentary 
canal and its secretions, which convert food into 
nutriment; with the organs of circulation—the 
heart, the blood-vessels, the lymphatics—distribut- 
ing nutriment all over the body; and with several 
organs serving to withdraw waste material from 
the body, such as the skin and the lungs. We 
must now gain an insight into a powerful organ, 
called the nervous system. It is distinct from all 
other systems in the body. The following are its 
functions : 
1. It connects tlie different portions and organs 
of the body into an organic unit or whole. Thus 
a violent shock to the nervous system, such as 
great anger or fear, may cause increased action 
of the heart, an accelerated pulse and immediate 
loss of consciousness. Here, then, the nervous sys- 
tem acts upon the blood-vessels ; these act upon the 
muscles, and this combined action causes not only 
single portions of the body to succumb, but the en- 
tire body as a unit. THE NERVOUS SYSTEM. 
131 
2. It animates, or governs, all movements of the 
muscles, whether these be voluntary or not. Thus, 
when a person endeavors to resist a yawn, to re- 
press laughter or tears, a distinct exertion of mus- 
cles is requisite for his effort. This is voluntary 
motion prompted by an act of his will; whereas, the 
churning motion of the stomach is an example of an 
involuntary movement governed by the proper 
nerves. 
3. It regulates the temperature, nutrition and 
secretion of the body. Thus, sudden fear often pro- 
duces a chilling effect in lowering the temperature 
of the skin ; weakness of the nervous system nearly 
always impairs the digestive process; intense an- 
guish frequently causes increased perspiration. 
4. It controls the processes of nutrition. This 
may be proved by the fact that the injury of a nerve 
leading to a tissue is frequently followed by the 
waste or destruction of the tissue. 
5. It receives impressions, which are communi- 
cated by its terminal branches. Lateral pressure 
against the eye-ball causes a luminous impression 
or image; this is owing to the pressure exerted 
upon the delicate terminal branches of the optic 
nerve (Lesson XXXIV). 
6. It conveys impressions to different portions of 
the body. In leaping, if a person alights upon the 
heel he will feel shocking pains in the back part of 
the head; the impression made at the foot is, by 
the nerves, conveyed to the head. 132 
FIRST LESSONS IN PHYSIOLOGY. 
7. It can generate influences which no other organ 
or system can produce, such as sight, smell, taste 
etc., etc. By virtue of this function, it puts the 
body in direct communication with the outer world. 
This is evident, for a living being without the senses 
of sight, smell, taste, hearing, touch and sensibility, 
if existing at all, would be utterly unconscious of 
the world around him. 
The performance of all these functions is com- 
prised under the term Innervation. 
The nervous system, although a continuous sub- 
stance, is conveniently subdivided into two sys- 
Fig. 29 
The Brain — (side view). 
Cb Cerebrum. Cbl Cerebellum. Mo Medulla Oblongata. 
terns: 1, tlie cerebrospinal system, and 2, the sym- 
pathetic system. The former comprises the cerebro- 
spinal axis—that is, the brain and the spinal cord— 
together with the cerebral and spinal nerves which 
emanate from this axis. The sympathetic system THE NERVOUS SYSTEM. 
133 
contains the chain of sympathetic ganglia and the 
nerves which they give off1. 
The Brain (Fig. 29) is a very soft substance, 
forming in man the enlarged upper terminus of the 
spinal cord. It is encased in the cavity of the cra- 
nium, which it fills, and from which it is difficult to 
be extracted entire. The brain substance of man 
generally varies in weight from 40 to 60 ounces, and 
it is universally admitted that, as a rule, the quan- 
tity of brain substance corresponds to the intellec- 
tual powers of the individual, although it is be- 
Fig. 30 
Two Nerve Cells and Nerve Fibers. From the Brain. 
Magnified 400 times. 
lieved that the quality of this substance also plays 
an important part. The brain consists of cells and 
fibers (Fig. 30), which are rendered visible only by 
a good microscope. The brain is divided into the 
large brain or cerebrum, the small brain or cerebel- 
lum—only one-eiglith as large as the former—and 
the enlarged spinal cord or medulla oblongata. The 
cerebrum in man and apes entirely covers the cere- 134 
FIRST LESSONS IN PHYSIOLOGY. 
Fig. 31. 
bellum. The cerebrum and cerebel- 
lum consist each of two hemispheres, 
one on the right, the other on the 
left side. The surface of the cere- 
brum is covered with a great many 
foldings and windings or convolu- 
tions, irregular in form and direction ; 
these are separated from each other 
by deep furrows. The cerebellum 
also has convolutions, but they are 
of a more regular form and direction. 
The spinal cord (Fig. 31) is the 
downward continuation of the 
medulla oblongata. It is a soft sub- 
stance contained in a bony cavity, 
formed by the vertebral column or 
back-bone (Lesson II). It extends 
nearly to the sacrum ; it is furrowed 
like the brain into two lateral, sym- 
metric parts. Between these two 
parts — that is, in the centre of the 
cord and through its entire length — 
runs a line canal, which originates in 
a point between the cerebellum and 
the medulla oblongata. 
The cerebro-spinal nerves originate 
in both the brain and the spinal 
cord, whence they ramify and spread 
all over the body (Fig. 32). They 
have the form of fibers and cells. A 
nervous fiber is often made up of 
minute tubes: each tube contains a 
The Spinal Cord, front view, with the projecting nerves cut off. .THE NERVOUS SYSTEM. 
135 
peculiar transparent, semi-solid substance which 
contains a thick fluid. The nervous fibers terminate 
in the organs to 
which they lead, 
and there form 
terminal branches. 
The nervous tubes 
vary in size from 
one-thousandth of 
an inch to much 
smaller sizes ; i n 
the spinal cord 
they are much 
smaller; in the 
brain they are 
smallest. 
The sympathetic 
system consists, 
like the brain, of 
cells and fibers. It 
is situated in front 
and at the sides of 
the spinal column; 
its ganglia or nerve- 
cells are connect- 
ed with one an- 
other, and with the 
spinal nerves by 
nerve-cords. The 
nerves given off 
from these ganglia chiefly follow the course of the 
Tig. 3 2. 
The Nervous System. 136 
FIRST LESSONS IN PHYSIOLOGY. 
blood-vessels, and are copiously distributed over 
the heart and about the stomach. 
The nervous system appears to be composed of 
two distinct substances—the gray and the white. 
In the cerebrum and cerebellum the white sub- 
stance is contained within the gray ; in the medulla 
oblongata and spinal cord, the gray substance is 
enclosed in the white. The nervous fibers and 
tubes are white ; the cells are gray. 
The central organ of the nervous system is the 
gray substance. This has been admitted by even 
those who used to think that the intellectual pow- 
ers had no connection whatever with the nervous 
system. Scientists agree that the gray substance 
evolves nervous power, while the white mainly 
serves to conduct nervous power. If the white ma- 
terial of the nervous system be compared to a net- 
work of telegraph wires spread over a large extent 
of territory engaged in war, then the gray substance 
may be likened to the controlling power at head- 
quarters—that is, the commander-in-chief. From 
all parts telegrams will be sent and transmitted to 
him along the wires stating the condition of affairs, 
while he not only sends and transmits messages, 
but makes his own combinations and plans, and 
forwards his orders to distant points along the 
wires. THE NERVOUS SYSTEM. 
137 
LESSON XXXI. 
THE NERVOUS SYSTEM—II. FUNCTIONS OF THE DIF- 
FERENT PARTS. 
The Functions of the Brain.—The thin layer of 
gray matter upon the hemispheres of the larger and 
smaller brain is intimately associated with mental 
operations. The reason for the convolutions and 
fissures on the surface of the brain is evident: they 
cause the layer of gray matter to be more extensive, 
and, consequently, other things being equal, to in- 
crease in quantity with the increase of convolutions 
and fissures. There are strong reasons why the 
main function of the cerebral hemispheres, and 
more especially that of the gray matter, seems to 
be the manifestation of intellectual powers and of 
powers of the will, viz.: 
1. In the animal kingdom, there is generally a 
correspondence between the quantity of gray mat- 
ter, depth of convolutions, and the sagacity of the 
animal. 
2. The gray matter of the brain is much more 
smooth during the first period of the infant’s life, 
and its increase corresponds with the development 
of intelligence. 
3. In diseases which have been known to com- 
mence at the circumference of the brain, and to 138 
FIRST LESSONS IN PHYSIOLOGY. 
pass toward the center, medical observations have 
found that the faculties of the mind are affected 
first; while in those diseases which commence in 
the central parts of the brain, and thence pass to- 
wards the cicumference, they are affected last. 
4. Experiments upon animals show that when the 
brain is gradually sliced away, the animal grows 
more dull and stupid as the quantity of brain cut 
away increases. 
Mental derangement may he caused by (1) im- 
perfect nutrition of the brain; (2) insufficient, or ex- 
cessive flow of blood toward the brain; (3) a per- 
verse condition of the blood ; (4) prolonged sleep- 
lessness ; (5) deep affliction or despondency. The 
usual symptoms of progressing derangement are 
weakened attention and loss of memory, which 
should be promptly met by avoidance of physical 
or nervous excitement, and by proper attention to 
the body. Insanity, a more continuous state of 
mental derangement, often springs from like 
sources, but sometimes from hereditary predisposi- 
tion. Insanity is characterized by lack of appreci- 
ation of the proper relations between the self and 
the external world. 
As persons can live though one of their lungs 
may he seriously injured, so life is not necessarily 
cut off in case one of the cerebral hemispheres has 
been damaged. 
The functions of the cerebellum, although not 
distinctly known as yet, seem to he the regulation 
of muscular movement. THE NERVOUS SYSTEM. 
139 
The function of the medulla oblongata consists 
in generating and controlling the motions of respi- 
ration and deglutition. The brain, cerebellum and 
the spinal cord can be sliced away one after the 
other without immediately destroying life ; where- 
as, an interference with the medulla oblongata is 
followed by instantaneous death. 
Functions of the spinal cord.— 1. To transmit 
sensitive impressions from its outer nerves to tlie 
brain. 2. To transmit tlie manifestations of the will 
from tlie brain to the spinal-motor nerves, which 
xesult in muscular activity. 3. To originate nerve- 
force independently of the brain whenever a stimu- 
lus is applied. Thus, when a stimulus, such as a 
drop of acid, is applied to the upper leg of a 
decapitated frog, he brings the toes of the corre- 
sponding foot to the place to wipe off the acid, but 
he will not leap away. In this case an impression 
has been made upon a sensitive nerve leading to 
the spinal cord. This sensitive or sensory nerve 
conveyed the impression to the spinal cord, the 
spinal cord made response to the impression 
through a motor nerve, and this response resulted 
in the reflex action of the foot. So when, inde- 
pendent of any influence of the brain, a small piece 
of bread is passed into the gullet by voluntary mo- 
tion, it will be urged onward to the stomach by in- 
voluntary motion—that is, by the reflex action of 
the spinal cord. The bread here acts as an excit- 
ing stimulus upon the spinal marrow, which gener- 
ates motor power; this motor power is ‘reflected’ 
back and produces the involuntary movements or 140 
FIRST LESSONS IN PHYSIOLOGY. 
reflex action of the muscles whose sensitive fibers 
were stimulated. 
The functions of the sympathetic system are not 
fully known as yet. It would appear, however, 
that while it is intimately connected with the other 
divisions of the nervous system, it presides over the 
actions of the alimentary canal, the glands, the 
blood-vessels and the heart. The heart may be re- 
moved from the body, and yet its rhythmical move- 
ments will continue for a number of minutes. This 
independent motor power on the part of the heart 
can only be explained by the existence of sympa- 
thetic ganglia or centers linked together by delicate 
nerve filaments, constituting of themselves a dis- 
tinct nervous system. 
Functions of Nerves.—If the nerve of a tooth be 
divided, the tooth has lost its sensibility. If the 
nerves leading to the biceps be severed, this muscle 
loses its motor power; it will no longer move the 
forearm. If these nerves be exposed in their course 
and irritated, the biceps will be thrown into violent 
movements, and intense pains experienced as com- 
ing from the biceps. These facts show that the 
nerves, generally speaking, are endowed with motor 
and sensory properties. That is to say, the nerves 
enable us to seize ordinary sensations, and to per- 
form acts of motion. 
There are nerves which are specially engaged in 
motion, and others, such as the optic nerve, which 
generate merely sensations. Either class may he 
injured without any damage to the other. Thus, a 
blind man rolling his eyes shows that, though his THE NERVOUS SYSTEM. 
141 
optic nerve is blighted, the motor nerves are in full 
action. So a limb may be paralyzed—that is, de- 
prived of all motion—and yet be very sensitive. If 
a motor nerve be divided, and a galvanic current 
applied to the portion of the nerve connected with 
the muscle, the muscle contracts. This shows that 
motor nerves act like telegraphic wires. 
Cases have been known where soldiers complain- 
ed of pain in their limb, which had long before been 
amputated. This is evidence that sensory nerves 
act like insulated wires, and, besides, that we refer 
pain and all other sensations to the parts which are 
supplied with nerves; we suppose the sensation to 
exist in the direction from which the nerves com- 
municate it. 
The nerves leading from the brain to the eye, ear, 
etc., etc., are in pairs; also those originating in the 
spinal cord. The latter are distributed nearly over 
the whole body, and are endowed with both motor 
and sensory properties. 
Read Dynamics of Nerve and Muscle. C. B. Radcliffe. Macmillan 
& Co. 142 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXXII.—RE VIEW. 
Lesson xxx.— 
1. Functions of the nervous system : 
(1) It connects the different parts and organs 
of the body into an organic unit or 
whole. 
(2) It animates or governs all movements of 
the muscles, whether voluntary or not. 
(3) It regulates the temperature, nutrition 
and secretion of the body. 
(4) It controls the processes of the organic 
life of the body. 
(5) It receives impressions which are gener- 
ated by its terminal branches. 
(6) It conveys impresssions to different por- 
tions of the body. 
(7) It can generate influences which no other 
organ or system can produce, such as 
sight, smell or taste. By means of this 
function, it puts the body in direct com- 
munication with the outer world. 
2. The nervous system is subdivided into the 
cerebro-spinal system and the sympathetic. 
3. The brain is divided into the cerebrum, tlio 
cerebellum and the medulla oblongata. 
4. The nervous system appears to be composed of 
two distinct substances, the gray and the white. REVIEW. 
143 
5. The gray substance is the central organ of the 
nervous system. 
Lesson xxxi.— 
6. The main function of the cerebrum seems to 
be the manifestation of intellectual powers, and of 
the will. 
7. The functions of the cerebellum seem to con- 
sist in the regulation of muscular movements. 
8. The function of the medulla oblongata is to 
generate and control the motions of respiration and 
deglutition. 
9. The functions of the spinal cord are—(1) to 
transmit sensitive impressions from its outer nerves 
to the brain; (2) to transmit the manifestations of 
the will from the brain to the spinal-motor nerves ; 
(3) to originate nerve-force independently of the 
brain whenever a stimulus is applied. 
10. The functions of the sympathetic system seem 
to be, to control the action of the alimentary canal, 
the glands, the blood-vessels and the heart. 
11. Nerves are generally endowed with motor and 
sensory properties. There are some which have 
only motor properties, and others which serve the 
purpose of generating sensations. 144 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXXIII. 
THE SENSES IN GENERAL.—THE SENSE OF TOUCH. 
The ideas, words and actions of a human being 
are largely dependent upon the soundness and the 
training of his sensory organs. 
Sensory organs are tools, or instruments, capable 
(1) of receiving impressions from the outer world, 
and (2) of making us conscious of those impres- 
sions. The means by which consciousness of im- 
pressions arises is sensation. Thus, the eye with 
its proper nerves is a sensory organ; it is capable 
of receiving the impression that a certain ribbon is 
blue; there is no other organ which can obtain such 
an impression. The eye, besides being capable of 
receiving that impression, is also capable of mak- 
ing us conscious of it, viz., the blue color. A man, 
after his eyes were removed, would be utterly in- 
caple of recognizing the blue tint, although his 
mind were never so clear. 
Sensation, in the present example, is excited by 
the action of the blue rays upon the retina ; so we 
speak of the sensation of cold, meaning by it the 
peculiar effect which cold has upon the nerves. 
Nearly all sensations come from without the 
"body—that is, from the outer world; they may be THE SENSE OF TOUCH. 
145 
called objective sensations. The yellow color of a 
lemon, the blue color of a ribbon, are objective sen- 
sations. It sometimes happens that the nerves of a 
sensory organ are affected when there is no objec 
tive or outside cause whatever. In this case they 
make us believe things that have actually no exist- 
ence. The eye, for example, if closed and pressed 
upon with a finger, develops a luminous image; 
this sensation is drawn not from the exterior world, 
but solely from within the body, hence, is not ob- 
jective, but subjective. The peculiar noise known 
as the ‘humming of the ear’ is also a subjective 
sensation. 
The sensory organs are five in number, viz., that 
of sight, hearing, touch, taste and smell. They are 
merely the peculiarly shaped termination of a par- 
ticular nerve. Impressions acting upon this termin- 
ation, or anywhere upon the nerve, whether coming 
from within the body or from without, affect it in a 
way that is peculiar to it, and concerning which 
nothing positive is known. Thus, the eye-ball is so 
constructed as to collect a great number of rays of 
light which affect the optic nerve, and thereby pro- 
duce the sensation of sight. What becomes of this 
sensation—that is, in what manner it produces the 
consciousness of sight, and in what manner it ulti- 
mately serves intellectual functions, we do not 
know, and probably never shall. The ear is utterly 
blind to the minute waves of light but very sensi- 
tive to the serial waves of sound. So each organ 
has a distinct structure, in virtue of which it has its 146 
FIRST LESSONS IN PHYSIOLOGY. 
particular manifestations; and the different senses 
may be compared to the various departments of 
government in a country, all of which together 
make up the government itself. 
THE SENSE OF TOUCH. 
Pressure, resistance, smoothness, roughness, hard- 
ness, softness, also cold and heat, are the most com- 
mon sensations excited by the sense of touch. The 
distinct structure of this sense consists in the 
nerves, which are spread out under the epidermis 
(Lesson XIII.) and within the dermis or cutis. It is 
a curious fact that the proper sensation is excited 
only on condition that the epidermis (which is 
known to contain no nerves) lie between the ex- 
panded nerves in the dermis and the exciting agent; 
that is to say, the stimulus or exciting agent must 
not be in direct contact with the dermis. If by ac- 
cident, as by burning, the epidermis has been de- 
stroyed, the sense of touch of the exposed nerve is 
reduced to a mere sense of pain. The termination 
of these nerves is not a flat surface, but consists of 
a great number of small, conical projections, called 
papillce. Different portions of the body possess 
different degrees of sensibility; compare the acute- 
ness of the finger tips with the dullness of the neck. 
The amount of sensibility is greatly lessened when 
the skin is stretched. 
A person who takes hold of an exceedingly cold 
iron bar experiences a sensation nearly like that 
obtained by touching one overheated. The tooth- 
ache caused by the contact of a tooth with ice THE SENSE OF TOUCH. 
147 
cream is the same as that resulting from severe heat 
applied to the tooth. These well-known facts show 
that an excess of cold or heat causes pain instead of 
impression of temperature; the pain is the same, 
by whichever it may be caused. 
Beyond the dermis the nerves are insensible to 
heat and cold; so the optic nerve, beyond its expan- 
sion—the retina—is no longer sensitive to light. 
The sense of touch is capable of great improve- 
ment. ‘ Professor Saunders, of Cambridge, who lost 
his sight when two years old, could distinguish by 
this sense genuine medals from imitation ones. 
Other blind men have, by their exquisite touch, 
been enabled to become sculptors, conchologists, 
botanists,’ etc., etc. 148 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXXIV. 
THE SENSES OF TASTE AND SMELL. 
Taste.—Sweetness, acidity and 'pungency are 
sensations most frequently excited by this sense. 
Its distinct structure consists of papillce spread over 
the tongue and portions of the cavity of the mouth. 
These papillm are the terminations of certain nerves 
coming from the brain. 
The sense of taste varies greatly in different per- 
sons ; it depends upon education, habits, and often 
upon imagination. It is diminished when the mu- 
cous surfaces of the tongue and mouth are affected, 
as in case of fever. It is a remarkable fact that 
when one part of the tongue is injured or paralyzed, 
the other has its capacity for tasting unimpaired. 
The sensations of taste are largely connected with 
those of other senses, such as smell, touch, and 
even sight. Thus, when the nose is held tightly 
closed so as to obtain no smell, the taste of many a 
substance is rendered difficult to distinguish; and 
it is very nearly tli(? same if the sense of sight is in- 
terfered with. 
Smell.—Fragrance and fetor are the principal 
sensations excited by- this sense. Its distinct struc- 
ture consists in olfactory nerves, which are spread THE SENSE OF SMELL. 
149 
over the interior surface of the nasal cavity, and 
protected by the latter. The olfactory nerves com- 
mence higher up in the nose ; the lower portion of 
the nose warms the cold air as it ascends, and thus 
protects the sensitive surface higher up. It also 
prevents the latter from becoming dry; this is of 
the greatest importance, as the function of the olfac- 
tory nerve ceases when the nasal chambers are dry. 
Substances, in order to produce smell, must have the 
gaseous form. This does not mean that all gases 
are odoriferous ; for oxygen, nitrogen, hydrogen, 
and many other gases, when in the pure state, are 
odorless. The fragrance of a rose, for erxample, is 
caused by particles of the flower being diffused in the 
air and transmitted to the olfactory nerve by means 
of a current of air inhaled during the act of inspira- 
tion. Like taste, smell may be sharpened by edu- 
cation and habit. 
As a rule, we judge localities with strong odors to 
be unhealthy. The escape of illuminating gas is 
easily detected by its odor, and may be fatal to the 
inmates of a room. Many strong odors, however, 
are harmless, while, on the other hand, quite in- 
odorous atmospheric air may contain the germs of 
the most dangerous epidemics. Such is the case 
with the air of low grounds, marshes and swamps. 
The connection between bad odors and pernicious 
effects is not yet cleared up ; the production of odor 
is closely connected with that of chemical action. 150 
FIRST LESSON’S IN PHYSIOLOGY. 
LESSON XXXV. 
SIGHT.—I. 
Light, colors of all kinds, and vision generally, 
are the principal sensations derived from the organ 
of sight. Its structure comprises the eye-ball and 
its accessory organs. The eye-ball owes its bulb- 
like form, solid appearance and resistance to pres- 
sure from without and within to a hard, fibrous 
membrane, covering it entirely, and having in front 
a transparent, horny part. 
The eye-hall consists of (1) three distinct coats, 
and (2) an optical apparatus. 
I. The three coats of the eye (Fig. 33): 
a. The Sclerotic.—This membrane is the outer 
coat of the eye ; four-fifths of it is white, opaque, 
hard, very little elastic ; it forms the rear portions 
of the membrane, the remaining one-fifth being the 
front part, a sort of window, called the cornea. 
The sclerotic gives form to the eye, serves for the 
attachment of muscles and envelops and protects 
the parts within. Both sclerotic and cornea are 
hard, but the cornea is colorless, transparent, and 
elastic. 
b. The Choroid.—It lines all the interior of the 
sclerotic with the exception of the optic nerve en- 
trance. It contains a capillary network of blood- 
vessels to feed and warm the eve. It is soft and THE SENSE OF SIGHT. 
elastic, and lined within by a black tissue, or pig- 
ment, to absorb unnecessary rays of light. Where 
this pigment is wanting, as in albinos, a confusion 
of sight is caused in daylight, probably because 
the unnecessary rays of light are reflected instead 
of absorbed. 
The Iris.—The bulb of the eye is divided into 
two unequal parts by a muscular membrane, the 
iris, forming a sort 
of curtain, with a 
central opening, the 
pupil, to admit the 
rays of light. The 
iris is lined on its 
rear surface by the 
choroid; in front it 
is provided with col- 
oring matter, which 
determines the color 
of the eye. The iris 
possesses only in- 
voluntary muscular 
fibers (ciliary pro- 
cesses'), by the aid 
of which it con- 
tracts—and thus en- 
larges the pupil— 
when a greater 
amount of light is 
needed; and it dilates—thus diminishing the aper- 
ture—when light is abundant. Thus, the iris regu- 
Fig. 3 3 
The Eye-Ball — Horizontal Section. 
S Sclerotic Coat. C Cornea. 
Ch Choroid Coat. / Iris. 
Cc Ciliary Processes. R Retina. 
O Optic Nerve (blind spot). 
* Aqueous Humor (anterior chamber). 
** Aqueous Humor (posterior chamber). 
L Crystalline Lens. 
Cv Vitreous Humor. 
Fc Yellow Spot (optic axis). 152 
FIRST LESSONS IN PHYSIOLOGY. 
lates tlie supply of light required for distinct vision. 
c. Retina.—Both sclerotic and choroid coats are 
pierced so as to admit the optic nerve. This nerve 
comes from the brain and enters the eye-ball from 
the rear. On reaching the interior surface of the 
choroid coat, the optic nerve divides into minute 
branches, which are so densely interwoven among 
each other that they form a nerve membrane, very 
delicate in structure, and about °f an inch in 
thickness. The point where it enters the choroid is 
not in the main axis of the eye-ball—a straight line 
drawn through the center of the pupil and bisecting 
the eye-ball—but is situated toward the inner cor- 
ner of the eye. This point is not sensitive to light, 
and, therefore, called the ‘blind’ spot. It is ascer- 
tained by the following simple experiment: 
14. Experiment.—Close the left eye; with the 
right eye look steadily at the cross below, holding 
the page at a distance of about twelve inches. 
In. this position both dot and cross will be seen 
distinctly. But if the book be slowly brought 
nearer to the face, the right eye being still fixed 
upon the cross, the dot will disappear during an in- 
stant, and as the book approaches the face, becomes 
visible again. Now, during the instant that the dot 
vanished out of sight, the image of the dot was on 
the blind spot of the retina—that is, on the region 
of the retina where the optic nerve enters the cho- 
roid. THE SENSE OF SIGHT. 
153 
II. The Optical Apparatus.—This is transparent, 
and refracts the light-rays to the retina. It consists 
of four lenses: a, the cornea, the network of the 
lenses ; h, the aqueous humor, the second lens from 
the front, a watery liquid containing a little salt; 
c, the crystalline lens, the third lens, one of the 
most peculiar bodies in existence, which has the 
appearance of a double-convex glass, and is situat- 
ed between the iris and the vitreous humor; the 
vitreous humor, the fourth lens. It is filled with a 
watery fluid, and forms by far the largest part of 
the eye-ball. 
Thus, the optical apparatus of the eye comprises 
two solid substances—a horny and a glassy one— 
and two liquids, all four serving the purpose of 
lenses. There is no artificial contrivance which ap- 
proaches it in excellence. 
The eyebrows serve to guard the eye against ex- 
cess of light; the eyelids, to keep the surface of the 
cornea moist; the eyelashes, to retain dust floating 
in the atmosphere. The remarkable mobility of 
the eye-ball is effected by a number of muscles, 
which act upon it in various directions. 
Read ‘ Our Eyes.’ By H. W. Williams. J. Osgood & Co.: Boston. 
Read * Diseases of the Eye.’ James Dixon. Lindsay & Blakiston : Phila. FIRST LESSONS IN PHYSIOLOGY. 
154 
LESSON XXXVI. 
SIGHT.—II. 
The accommodation of the eye.—If a small box, 
blackened on the inside, be provided with a convex 
lens or a watch-glass, placed in one of its sides— 
which is then the front side of the box—we have a 
camera obscura. The lens collects rays of light 
from the objects before it; an image of these ob- 
jects is produced somewhere in the box. We can 
catch the image by inserting a piece of ground 
glass, and it will then be distinctly visible; or, if a 
sensitive photographic plate be taken in place of 
the glass, the image will be fixed on the plate. This 
is the principle of photography. If the image be 
examined, we shall find that only those spots are 
pictured on it distinctly which are nearly at the 
same distance from the lens; the image of objects 
farther off is brought to a focus in front of the 
plate; that of objects nearer to the lens, behind 
the plate. 
A little thinking will enable us to see that the 
eye may be compared to such a camera. The box 
corresponds to the sclerotic coat; the lens answers 
to the cornea and crystalline lens ; the glass plate, 
or the back of the box, to the retina. Were we to 
fill the box with water, this fluid would indicate the 
fluids of the eye. It will here be observed that in THE SENSE OF SIGHT. 
155 
the camera we have nothing for the iris; so we 
must imagine an opaque plate with a hole in the 
center, suspended directly behind the watch-glass, 
whose purpose it should be to regulate the supply 
of light. But the camera has yet another defect, 
viz.: it has no means of adjusting the focus so as to 
view objects at different distances. In order to ob- 
tain the images of objects at a greater distance we 
might move the glass plate toward the lens; and, 
on the other hand, to receive the images of objects 
situated nearer, the plate would have to be pushed 
farther back. We might also slide the lens forward 
and backward, as is done in the ordinary camera. 
Or we might effect the adjustment in still another 
way : take a very convex lens to obtain the image 
of nearer objects, and exchange it for a less convex 
one when the image of distant objects is to be 
thrown on the plate. 
But the simplest way of all would be, if one and 
the same lens could be made to alter its convexity 
so as to adjust itself of its own accord to distances. 
This actually occurs in the eye. 
15. Experiment.—Stick two pins upright into a 
straight piece of wood, not quite, hut nearly, in a 
straight line, with the eye applied to one end of the 
wood ; one pin to he about six inches from the eye, 
the other about twelve inches. If we look at the 
nearer pin first we shall see it very distinctly, while 
the other pin produces a blurred image. If now we 
look at the other pin the blurred image will at once 
become distinct, but we feel that somewhere in the 
eye an effort had first to be made. We observe, 156 
FIRST LESSONS IN PHYSIOLOGY. 
also, that the nearer pin now yields a blurred image, 
and on repeated trials, it appears evident that we 
utterly fail to see both pins distinctly at the same 
instant of time. 
This experiment, as well as a great many familiar 
facts of the kind, proves that the eye can see an ob- 
ject distinctly at different distances. Hence, it must 
be that the eye has the capacity of adjusting itself 
according to the dis- 
tance of objects. 
This accommoda- 
tion on the part of 
the eye is brought 
about by a change 
in the form of the 
crystalline lens. The lens is flattened when a more 
distant object is viewed (Fig. 34, A), and becomes 
more convex (B) when the object to be viewed is 
nearer. 
-Fig. 34 
The distance of distinct vision is about ten 
inches. This means that, generally speaking, no 
object which is brought within less than ten inches 
of the eye can be rendered distinctly visible without 
effort. There is a certain range within which alone 
the adjustment of the eye can take place. It is 
subject to personal variation. 
Short-sightedness and long-sightedness arise often 
from a defect in the adjusting powers of the eye. In 
some persons the cornea is more convex than usual, 
or the refractive powers of the eye are greatly in- 
creased. Such persons are short-sighted (or near- 
sighted) : they can see only near objects distinctly, THE SENSE OF SIGHT. 
157 
because objects at ordinary distances have their 
rays come to a focus, not on the retina, but in front 
of the retina. The images of these objects are 
thereby rendered indistinct, for the rays, instead of 
blending into points, form minute circles upon the 
retina, which causes the blurred appearance of the 
images. Some people, especially such as are ad- 
vanced in years, have the cornea flattened—that is, 
not sufficiently convex—and for this reason the 
rays from objects at ordinary distances are not 
brought to a focus on the retina, but behind it. 
Either defect is amended by suitable glasses. Short- 
sighted persons require concave glasses—glasses 
thinnest in the center—which counteract the greater 
convexity of the eye. Long-sighted people wear 
convex glasses—glasses thickest in the center—so 
as to render the eye apparently more convex. 
Visible Direction.—From the observation of all 
images formed by rays of light after crossing each 
other through an aperture, it is evident that the 
images or external objects are inverted upon the 
retina. The probable reason why we do not see all 
objects inverted is our habit of supposing that the 
point from which a ray strikes us lies in the direc- 
tion from whence the ray comes. Thus, a point at 
the top of a steeple, although on the retina pictured 
below, is by the mind supposed to be situated above, 
because its ray strikes the retina from above. (See 
First Lessons in Physics, Lesson XXXIV.) 
Duration of Impressions upon the Retina.— 
When the retina has received an impression of light 158 
FIRST LESSONS IN PHYSIOLOGY. 
it retains the impression a little longer than during 
the actual time in which the light lasts. A lumin- 
ous impression, however short the time during 
which the light itself lasts, usually remains on the 
retina one-eighth of a second. Supposing that two 
luminous points were to act successively upon the 
retina in a less interval than one-eightli of a second, 
then the two impressions would appear as one im- 
pression. This explains why a lighted stick, if 
turned round very rapidly by the hand, appears as 
a luminous circle ; or wdiy a vibrating string may 
be visible as a sort of broad film. 
Color-blindness is probably a defect in the retina, 
or in the humors of the eye, of persons who are un- 
able to distinguish between certain colors, and 
sometimes even have no appreciation of any color. 
They are said to be color-blind. 
The sensitiveness of the retina is readily dimin- 
ished. If we look steadily at an intensely bright 
light, the part of the retina on which the rays fall is 
rapidly weakened, and even temporarily blinded. 
This may be ascertained by turning from the bright 
light toward a moderately lighted surface ; the dark 
spot which then comes to view is the result of mo- 
mentary blindness in that part. It is also injurious 
to strain the eye when the supply of light is insuf- 
ficient, as when persons attempt to read during twi- 
light. THE SENSE OF HEARING. 
159 
LESSON XXXVII. 
HEARING. 
Sound, noise and music are the principal sensa- 
tions derived from the sense of hearing. The organ 
of hearing is the ear. The eye has an optical ap- 
paratus to convey waves of light to the terminal 
branch of the optic nerve, the retina; so the ear has 
a complex apparatus for the transmission of waves 
of sound to the terminal branches of the auditory 
nerve. 
Fig. 35. 
The Ear.—Transverse Section through the Side Walls of the Skull. 
OE Outer Ear. M Hammer. 
ET External Tube. / Anvil. 
Ty Tympanic Membrane. va, ha, vpa Semicircular Canals. 
D Drum or Tympanum. Coc Cochlea. 
Eu Eustachian Tube. AN Auditory Nerve. 160 
FIRST LESSONS IN PHYSIOLOGY. 
The general structure of the ear (Fig. 35) consists 
of (1) the outer ear; (2) the middle ear; (3) the 
labyrinth, a complicated system of canals, which 
is filled with a liquid resembling water. 
1. The outer ear (Fig. 35, OE) is a cartilage, 
shaped somewhat like a funnel, and provided with 
muscles. On account of its shape and elasticity it 
is peculiarly adapted to collect and transmit waves 
of sound. 
2. The middle ear consists of (1) the external 
tube, E T, and (2) the drum, or tympanum, D 
(scarcely visible in Fig. 35). The former may be 
considered the tube of the funnel, formed by the 
outer ear. The outer wall is cartilaginous; its inner, 
of bony tissue. Its rear end is closed by the tym- 
panic membrane, Ty, a translucent, delicate mem- 
brane which is stretched across the tube in an ob- 
lique direction. Were it not for this membrane the 
external tube and the drum would form a single pas- 
sage. The drum is a cavity filled with air, bordered 
at one end by the tympanic membrane, at the other 
by two openings—one called the oral window (Fv, 
Fig. 37), the other the round window (Fc, Fig. 37). 
In the fresh state each of these openings is firmly 
closed by a membrane; in the dry skull both are 
wide open, and lead into the labyrinth. The drum 
also communicates with the roof of the mouth by 
means of a long passage called the Eustachian tube, 
Eu. This canal serves the purpose of equalizing 
the temperature as well as the pressure of air on THE SENSE OF HEARING. 
161 
either side of the tympanic membrance, an import- 
ant item for the healthy state of the ear. 
The drum contains three small bones (Fig. 86); 
the hammer, M, the handle of which {Mm) is fasten- 
ed to the inner side of the tympanic membrane; the 
anvil, I; and the stapes 8. The head of the ham- 
mer forms a joint with the anvil; the foot-plate of 
the stapes closes the 
oval window. These 
small bones make con- 
nection between the 
tympanic membrane 
and the labyrinth, or 
more properly, the oval 
window (Fv, Fig. 37) 
which leads to the laby- 
rinth. They convey the 
vibrations of the tym- 
panic membrane to the 
labyrinth. 
3. The Inner Ear, or Labyrinth, consists of (1) 
the vestibule (not visible in Fig. 37), a chamber 
which is connected with the drum by means of the 
oval window. (2) Three hoop-like semi-circular 
canals, viz., two vertical ones, va, vpa, and one hori- 
zontal, ha. (3) The cochlea, c, a cavity having the 
form of a spiral shell, with two and a half windings. 
Thus, the entire labyrinth consists of chambers 
and canals which are hollowed out in the solid por- 
tion of the temporal bone (Lesson II.). Each such 
cavity contains a fluid in which are floating minute 
branches of the auditory nerve (AN. Fig. 35). 
\ Fig. 36 
The Small Bones of the Ear. 162 
FIRST LESSONS IN PHYSIOLOGY. 
The sensation of sound is excited in about this 
way: The outer ear collects waves of sound, and 
conveys them through the external tube to the tym- 
panic membrane, which is shaken by these waves, 
and causes the three small bones to vibrate. The 
last of these bones, the stapes, impinges upon the 
vestibule, to which it imparts its vibrations. These 
are at once taken up by the 
fluid in the vestibule and 
transmitted to the remain- 
ing liquids in the various 
canals composing the laby- 
rinth. The motion of the 
liquids causes the minute 
fibers and hair like term- 
inations of the auditory 
nerve, which are floating 
freely in the liquids, to vibrate; and their vibrations 
are carried by the auditory nerve to the brain. 
Fig■ 37 
The Labyrtnth—(ext. view). 
Read ‘Deafness.’ E. B. Lighthill. Carleton: New York. 
Read ‘ Sight and Hearing.’ J. H. Clarke. Scribner & Armstrong : N. Y. REVIEW. 
163 
LESSON XXXVIII. — REVIE W. 
Lesson xxxiii.— 
1. Sensory organs are capable (1) of receiving im- 
pressions from the outer world, and (2) of making 
us conscious of these impressions. 
2. The means by which the consciousness of im- 
pressions arises within us is called sensation. 
3. The structure of the sense of touch consists in 
nerves which are spread out under the epidermis. 
Lesson xxxiv. 
4. The structure of the sense of taste consists in 
papillce spread over the tongue and portions of the 
cavity of the mouth. Papillae are the terminations 
of certain nerves coming from the brain. 
5. The structure of the sense of smell consists in 
olfactory nerves, which are spread over the interior 
surface of the nasal cavity. 
Lesson xxxv.— 
6. The structure of the sense of sight consists in 
two eye-balls, each of which comprises (1) three 
distinct coats, and (2) an optical apparatus. 
7. The three coats of the eye-ball are: 
(1) The sclerotic coat; 
(2) The choroid coat; 
(3) The retina. 164 
FIRST LESSONS IN PHYSIOLOGY. 
8. The retina is the terminal expansion of the op- 
tic nerve. Both optic nerves unite into one optic 
nerve in the brain. 
9. The optical apparatus is made up of— 
(1) The cornea; 
(2) The aqueous humor; 
(3) The crystalline lens; 
(4) The vitreous humor. 
Lesson xxxvi.— 
10. The eye is capable of adjusting itself accord- 
ing to the distances of objects. This power is call- 
ed the accommodation of the eye. 
11. The distance of distinct vision of the eye is 
about ten inches. 
12. Short-sightedness and long-sightedness are 
remedied by concave and convex glasses, respec- 
tively. 
13. The visible direction of the eye is our habit 
of supposing the point from which a ray strikes it 
to lie in the direction from whence the ray comes. 
14. The retina retains impressions a little longer 
than during the actual time in which the light lasts. 
15. Color-blindness is a defect of persons in dis- 
tinguishing between certain colors, or the impossi- 
bility of detecting any color. 
16. The sensitiveness of the retina is readily ex- 
hausted. 
Lesson xxxvii.— 
17. The structure of the sense of hearing consists 
of two ears, each of which comprises (1) the outer 
ear, (2) the middle ear, (3) the inner ear or labyrinth. REVIEW. 
165 
18. The outer ear is peculiarly adapted to collect 
and transmit waves of sound. 
19. The middle ear consists of (1) the external 
tube, and (2) the drum or tympanum. These are 
separated from each other by the tympanic mem- 
brane. The drum contains three small bones: the 
hammer, the anvil and the stapes. Its inner end 
contains the oval window and the round window. 
The three small bones connect the tympanum—that 
is, the tympanic membrane—with the oval window. 
20. The labyrinth or inner ear consists of the ves- 
tibule, three semi-circular canals and the cochlea. 
21. The labyrinth is filled with liquids, in which 
are floating the terminal fibers and filaments of the 
auditory nerve. 166 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XXXIX. 
THE MIND. 
We have now seen that man possesses a passive 
framework composed of bones, which form the 
levers by which he accomplishes his movements. 
These levers are acted upon by the muscles, which 
thereby become the proper organs of motion. 
These, in turn, are controlled to a greater or less ex- 
tent by the nervous system. The bones, muscles, 
sensory organs and nervous system have very prop- 
erly been called the ‘Animal Apparatus of Life ’; 
they are found in all the higher animals. 
Now, there is another function apparent in the 
human body, in virtue of which a constant build- 
ing-up or repairing of these essentials of animal 
life is going on within the body, which is called for 
by the continuous wear and tear of bones, muscles 
and blood. This function is performed by organs 
which (1) make blood, such as the alimentary canal 
and the lymphatics ; (2) keep file blood in circula- 
tion, as the heart; and (3) maintain it in a pure 
state, as the lungs. These organs have been com- 
prised under the head of ‘ Organic Apparatus of 
Life,’ and are also influenced by the nervous sys- 
tem. 
The animal apparatus of life intimately connects THE MIND. 
167 
man with the highest animals; the organic appa- 
ratus of life with the vegetable kingdom. 
Many of the higher species of animals have been 
greatly changed by domestication. Their ferocious 
habits have been modified, their instincts improved, 
their intelligence developed; but in spite of all this, 
domesticated races, when left to themselves, after a 
few generations return to their original wildness. 
And the superiority of training which an individual 
animal may have received never benefits his species 
or race. 
With the human toeing it is very different. Man is 
gifted not only with an unlimited capacity for men- 
tal accomplishment, but also with a never-ending 
desire to acquire new mental attainments. And in- 
dividuals of ability and talent seldom fail to benefit 
their race. From these gifts spring the eagerness 
of the human being for education. Education con- 
sists chiefly in repressing the lower habits of hu- 
man nature, and in developing its nobler qualities. 
Beyond all this there exists yet something more 
elevated, though more difficult to analyze, viz.: the 
faculty which enables us to conceive the idea of the 
infinite and our relations to the infinite, by which 
we possess aspirations after Truth, Goodness, Right 
and Beauty. 
If the capacity for, and desire after, mental ac- 
complishment, referred to above, be expressed by 168 
FIRST LESSONS IN PHYSIOLOGY. 
the term Mind, we must recognize (a) that the mind 
is greatly dependent upon the condition and the 
state of health of the body, and (b) that the body, in 
turn, is easily affected b}7- the mind. There are 
many familiar facts to testify to this, among which 
may be mentioned as proofs of a : (1) The necessity 
of proper food to nourish the brain : that is, of pure 
blood with an abundance of oxygen. Wherever 
this is wanting, mental activity decreases. (2) The 
effect of local affections of the brain, as when a per- 
son has received a severe blow on the head. (S) The 
effect of intoxication, or (4) of poison, or (5) of fever, 
or other bodily disorder. And among the numerous 
proofs of b we have : (1) The well-known effects of 
anxiety, fear or joy on the body. (2) The injurious 
effect of mental depression on bodily functions. (3) 
The self-restraint exerted by the body in obedience 
to efforts of the will. 
Attention.—Every individual has a certain capa- 
city of concentrating his faculties upon a task which 
he wishes to perform. Thus, he may wish to acquire 
knowledge, to repress his anger, to control his 
habits, or to observe strict honesty in his dealings 
with others ; but for any and all of these activities 
he needs a certain power of will. This power of 
will he must bring to bear upon his faculties in 
order to be successful. If all his faculties are di- 
rected upon any one activity at a time, as for 
example, upon the acquisition of mathematics, he 
-nearly excludes them from any other activity, and 
is then said to be attentive. Attention, therefore, is PERCEPTION. 
169 
the concentration by the power of will of all the 
faculties upon some one activity to the exclusion of 
others. Thus, a young person who is bent over his 
slate, concentrating all his activities upon an arith- 
metical problem, is almost unaware of what is go- 
ing on around him. His will deprives the sensory 
organs of nearly all their faculties, which are now 
spent in inward attention. On the other hand, a 
countryman visiting a large town for the first time, 
does not follow any particular train of thought, but 
has his senses busily engaged by the novelties with 
which he is impressed at every step. His will does 
not direct his faculties to any special activity; they 
are devoted to his sensory organs, and, consequent- 
ly, his attention is wholly outward. 
Perception.—A sleeping person may unconscious- 
ly start at a loud noise, and then resume his former 
state of sleep. His sensation was correct; he was 
conscious of it, but he had no distinct perception 
regarding the source or nature of the sound, be- 
cause he bestowed no attention upon it. Or, if the 
young student, referred to above, had been less ab- 
sorbed by his mathematical problem, he might have 
unconsciously heard cries outside of his room, and 
yet not have had a distinct perception of them; and 
having finished his task, and hearing the cries again, 
this time with his full attention directed toward 
them, he may dimly remember to have heard them 
before. While, then, a sensation is an impression 
upon a conscious state of mind, a perception is an 
impression upon a conscious state of mind accom- 
panied by attention; or, perception = sensation -4- 170 
FIRST LESSONS IN PHYSIOLOGY. 
attention. From the preceding it will be clear that 
a person having heard a loud report at a distance 
repeated several times, in speaking about it will, 
with perfect propriety, describe the sensation which 
the sound produced in himself, and which, as yet, 
he may attribute to the roaring of cannon, or thun- 
der, or to an explosion. Now, let him arrive on the 
spot from whence the noise proceeded. Suppose it 
to have been due to the practice of artillery. He 
will then perceive the source and the nature of the 
report, and thus obtain a distinct perception of the 
cannon, which he may afterwards describe. He has 
now learned something outside of himself, and 
his mind is no longer engrossed with its own 
sensation. 
Ideas.—After his return, the same person can ac- 
curately picture the cannon and represent to himself 
its effect; that is, he has retained a mental repre- 
sentation or idea of the object and its effect. This 
idea he can afterwards reproduce in audible or visi- 
ble signs—words; or, if he is an artist, he can 
paint it. An idea is the mental representation of 
an object; it calls for a higher mental activity than 
perception. 
A succession of ideas gives rise to thought. The 
conscious mind is incessantly engaged in thought. 
We might continue, and treat of the laws of 
thought, emotion, habit, will, sleep and dreams, but 
the limits of the present volume have now been at- 
tained. For further information, the young student 
should, throughout the course, peruse the works of 
reference indicated. 171 
DEFINITION OF PHYSIOLOGY. 
Definition of Physiology.—Physiology is the 
science of the functions of animals and vegetables. 
Human 'physiology is the science which treats of 
the functions of the human body and the manner 
in which they are brought about. 
Read Mental Hygiene. D. A. Gorton. Lippincott: Phila. 
Expression of the Emotions. Darwin. 
Body and Mind. Maudsley. Macmillan & Co.: New York. 
Diseases of Brain. By Forbes Winslow. Churchill & Son: Lond. 
Disorders of the Mind. By F. Winslow. Churchill & Son : Lond. 172 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON XL. 
ALCOHOL — STIMULANTS —NARCOTICS. 
ALCOHOL. 
1. Properties.—If sugar be allowed to ferment, 
one of the products of this fermentation is alcohol. 
Pure alcohol is a highly volatile thin-fluid, combus- 
tible liquid, of a vivifying odor and burning taste. It 
is specifically lighter than water, having a specific grav- 
ity of about 0.8, which means that a given volume of 
it weighs only about T87 as much as the same volume 
of pure water. Its boiling point is lower than that of 
water, being about 175° Fahrenheit (that of water 
being 212 F.°). 
It has a strong attraction for water, and mixes with 
it in all proportions. What is known as the ordinary 
alcohol of commerce is pure alcohol mixed with 
water. 
A drop of it placed upon the skin produces the sen- 
sation of cold, which is due to its rapid evaporation. 
2. Uses. —Alcohol is used in the arts for many 
useful purposes. On account of its great capacity of 
dissolving substances, it is used as a solvent of rosins, 
cements, pharmaceutical preparations, and for the 
manufacture of perfumes and essential oils. ALCOHOL. 
173 
On account of its capacity for preserving vegetable 
and animal fibres, it is used to preserve anatomical 
preparations and articles of food. 
On account of its stimulating powers it is used by 
physicians in small quantities greatly diluted with 
water, to promote or stimulate the action of organs 
such as the heart or stomach. But instead of usino- 
O 
pure alcohol diluted with water, pure light wines are 
usually recommended by physicians on account of 
their flavor, as all such wines contain a small portion 
of alcohol. 
3. General Effects. — Beer, wine, liquors and what- 
ever other names the different beverages may bear 
that are used by mankind on account of the effects 
which the smaller or greater percentage of alcohol 
they contain may exert, are known for their general 
effects upon the human system as well as for the cer- 
tain special effects which we will describe hereafter. 
Most people use them as stimulants, some as medicine, 
and some — the unfortunate victims of a slavish de- 
sire— as a means of reaching an early grave. 
What is a “ stimulant ? ” We define it as a means of 
increasing the vitality of some organ, or of the human 
system in general. Physicians not infrequently pre- 
scribe some one of the alcohol-containing liquids which 
we have mentioned before, for the purpose of invig- 
orating some sluggish organ, such as the stomach or 
heart of a sick or convalescent person; writers some- 
times avail themselves of the “ stimulating” effectof a 
little wine, to accelerate the action of their brain; men 174 
FIRST LESSONS IN PHYSIOLOGY. 
about to expose themselves to the dangers of a peril- 
ous journey, or to severe inclemency of the weather, 
provide themselves frequently with wine or brandy to 
guard against loss of heat or against other privations. 
A healthy, vigorous person requires no artificial 
stimulus to carry on the regular functions of his sys- 
tem; consequently he needs no stimulating drinks. 
This does not mean, however, that a small quantity of 
alcohol greatly diluted with water, such as beer or 
light wine, taken in small quantities and only infre- 
quently, perhaps once or twice a day, at meal times, 
will produce a great deal of harm, provided the system 
is used to it, and readily assimilates and tolerates it. 
But there certainly exists no sound reason why young 
persons should use stimulants. 
Large doses of alcoholic liquids produce intoxication 
and delirium tremens. The brain is over-stimulated; 
the reasoning faculties are in disorder ; the liver, heart 
and connective tissues accumulate fat; the channels 
of nutrition have become impaired, and the whole 
system has degenerated. When a person has sunk to 
this lower stage he is said to have delirium tremens, 
which is usually the result of continued intoxication. 
1. Special Effects:—1. On the Heart.— The reason 
why small quantities of alcohol which are greatly 
diluted with water stimulate the system, is due to the 
fact that the alcohol enters the circulation, permeates 
the body and is burnt up or oxidized within the system, 
yielding, as a result of this combustion, heat and vital 
force to the tissues of the body. Since, then, the circu- ALCOHOL. 
175 
lation is stimulated, it follows that the action of the 
heart is invigorated; the structural part of this organ, 
however, suffers no change. Larger doses of “ stim- 
ulants,” however, exert a depressing influence upon 
the heart, rendering it flabby, dilated, and sometimes 
fatty, so as to reduce its action; they lower the tem- 
perature of the body and generally retard the action of 
the cells. In the language of a medical author — 
O O 
“ The agreeable excitement at first caused by such 
“ doses of alcohol is succeeded by a reaction, char- 
“ acterized by lassitude and drowsiness, the latter 
“condition usually lasting longer than the previous 
“one of exhilaration.” 
In many diseases it is desirable to animate the 
circulatory system to greater action; this is especially 
the case with fever patients ; they can stand consider- 
able quantities of alcohol without intoxicating effects; 
and as alcohol lowers the temperature of the body, the 
fever-heat is lowered also, owing to the use of alcohol, 
and thereby improves the condition of the patient. 
2. On the Lungs.—Persons who are addicted to 
excessive drinking, and especially those “ chronic ” 
drinkers who are predisposed to lung troubles, are 
liable to pneumonia and to consumption. 
3. On the Stomach.—The immoderate use of alco- 
hol may produce chronic inflammation, congestion or 
catarrh of the stomach and the duodenum. The inner 
coat of the stomach is greatly changed by the exces- 
sive use of alcohol, and loses its capacity for secretion 
and absorption. As a result of this, digestion in the 176 
FIRST LESSONS IN PHYSIOLOGY. 
stomach is impaired aud the nutrition of the body 
weakened. 
4. On the Liver.—A commonly occurring disease 
of the liver, known as cirrhosis of the liver, in which 
this organ becomes hardened and shrunk, arises from 
an abuse of alcoholic drinks, more especially of spirits 
undiluted with water. Most cases of this kind, when 
once established, terminate in death. 
5. On the Blood and Blood-vessels. — Whatever im- 
pairs the functions of the stomach is certain also to 
impair the proper condition of the blood and the nutri- 
tion of the body; so that an habitual excess of alco- 
hol cannot but deteriorate the “life-giving” liquid. A 
too frequent use of alcohol tends to change the coats 
of the blood vessels. Both changes combined— that 
of the blood and the vessels that circulate it through 
the body — together with the injurious influence which 
large doses of alcohol have upon the nerves, have a 
baneful effect upon the entire system. 
6. On the Brain and Nervous System. — A large 
amount of alcohol acts on the nerves and nerve centers 
as a poison. In the latter stage of drunkenness or 
debauch it may cause insensibility to such a degree 
as to produce death. We quote from an expert writer 
on the subject: “ In slight cases of intoxication pro- 
longed drowsiness may be the chief symptom; but in 
the more severe forms the patient is quite insensible; 
the power of motion is in complete abeyance; the 
breathing is loud and deep; the face is usually pale; 
the pupils are generally dilated; the pulse is slow and ALCOHOL. 
177 
labored; the skin feels cold and clammy; the temper- 
ature is low.” 
Effects of Excessive Use of Alcohol:— (1) Intoxica- 
tion.— The ordinary manifestations of intoxication 
are too well known to require description. Headache, 
vertigo, vomiting, coated tongue, staggering walk, 
disordered vision, loss of appetite, increased thirst, 
and general lassitude or depression; all these phen- 
omena, or any of them, are the ordinary results of in- 
toxication. If made a habitual occurrence, intoxica- 
tion passes into wrhat is known as “ chronic alcoholism,” 
where those symptoms are greatly intensified, and give 
rise to muscular tremors, loss of sleep, noises in the 
ears, dull headaches, foul breath, redness around nose 
and mouth, dyspepsia, fatty heart, impaired mental 
condition and general weakness of body and mind. 
(2) Delirium Tremens.—Chronic drinking may 
be followed by delirium tremens, which is a worse 
form of “chronic alcoholism,” although it maybe 
produced by other causes as well. Its symptoms vary, 
but as a rule are described as follows: “ Inability to 
take food; marked anxiety and restlessness; tremor 
of the voluntary muscles; furred and tremulous 
tongue ; cool skin, which is frequently bathed in per- 
spiration; cold hands and feet, and a soft, weak pulse. 
There is complete insomnia, or short periods of sleep 
are interrupted by terrifying dreams, and the patient’s 
nights are tormented with visions of horrid insects, 178 
FIRST LESSONS IN PHYSIOLOGY. 
reptiles and other objects pursuing him and eluding 
his attempts to escape from them or to seize them. 
His mental impairments increase, and attempts at sui- 
cide are common. In this stage a prolonged sleep may 
occur, and the disease thus terminate. If it continues, 
the strength fails, the pulse diminishes, the tremor in- 
creases, the tongue gets dry and brown in the center, 
the patient talks incessantly and picks at the bed- 
clothes and death is ushered in by a delusive calm, or 
takes place in a paroxysm of violence.” 
(3) Alcoholic Insanity. — This species of insanity 
is a result of alcoholic poisoning; it occurs when a 
person has inherited a strong tendency to mental dis- 
turbance and uses alcohol to excess. Not infrequently 
this results in a wild delirium called mania a polu, 
during which attempts to commit suicide are often 
made; or in a melancholical state of mind, which leads 
to the same suicidal disposition. If sleeplessness, 
mental depression and a general loss of nervous power 
associate themselves with those symptoms, this kind 
of insanity becomes chronic, and may cause paralysis, 
permanent insanity and death. 
STIMULANTS. 
Wine is the fermented juice of the grape. One 
thousand parts of it contain, as a rule, about 900 parts 
of water, 80 parts of alcohol, and 20 parts of various 
bodies, such as acids and ethers. 
Wines containing a large portion of carbonic acid STIMULANTS. 
179 
gas are c;ilied “ sparkling ” wines; such as contain a 
great deal of “acid” are called “ sour” wines ; those 
containing much free sugar, “sweet” wines, and 
those containing a large quantity of alcohol, “ strong ” 
or “ heavy ” wines. 
Red wines contain from about 10 to 15 per cent of 
alcohol, which means that 100 volumes of such wines 
contain from 10 to 15 like volumes of alcohol. White 
wines contain less. 
Rum is the product of the distillation of fermented 
sugar cane. 
Brandy or Cognac is a result of the distillation of 
strong wines. 
Arac is obtained by distilling rice or palm juice. 
Whisky is a product of the distillation of wheat, 
rye or corn. 
Liquors, in general, are highly flavored liquids con- 
taining a large percentage of alcohol mixed with large 
quantities of sugar. 
Beer contains less alcohol than wine; generally not 
over five per cent. 
Coffee and Tea are mild stimulants, yet they should 
not be taken in strong doses, nor in large quantities. 
Their effect seems to be to assist digestion; they are 
therefore generally taken after meals. But their in- 
temperate causes indigestion, nervousness and other 
troubles. 
Chocolate and Cocoa are not so stimulating as coffee 
and tea, but are much more nutritive. 180 
FIRST LESSONS IN PHYSIOLOGY. 
NARCOTICS. 
Narcotics are remedies which induce sleep or insensi- 
bility. The principal narcotics in use are (1) opium 
and morphium) or morphia, (2) chloroform, (3) sul- 
phuric ether, (4) chloral, (5) cocoaine, (6) bromide 
of potassium, (7) belladonna, (8) digitalis, (9) alcohol. 
In smaller doses these substances cause sleep ; 
in larger doses, insensibility, which may terminate 
fatally. 
1. Opium — Laudanum and morphium — these sub- 
stances are the most effective and reliable narcotics. 
Laudanum is a preparation of opium. Morphium or 
morphia, is the most valuable part of opium; it is the 
morphium in opium which renders opium effective as 
a narcotic. This class of narcotics may relieve pain 
even without causing sleep. Opium is administered 
especially in typhus fever and other disorders, when 
delirium and loss of sleep may become dangerous to 
life. But opium also acts as a drawback, as it tends 
to disturb the stomach. And the habit of “ eating” 
opium is a terrible calamity. 
2. Chloroform.—This powerful anaesthetic was first 
introduced by Simpson, of Boston, 1847. It is a very 
convenient remedy to annul pain, but a very danger- 
ous one, as some persons are particularly liable to be 
affected by it in the heart. 
3. Sulphuric Ether. — This is a colorless liquid, the 
vapors of which, when inhaled, blunt the senses, es- 
pecially the sense of pain, so that even severe pains 181 
NARCOTICS. 
are no longer felt, and short operations may be per- 
formed during the time the inhalation goes on. When 
the inhaling process ceases, sensibility returns almost 
immediately. It is a much safer narcotic than opium 
or chloroform. 
4. Chloral. —This substance is also liable to affect 
the heart, and is a valuable remedy for simple sleep- 
lessness. 
5. Cocoaine.— This is an alkaloid obtained from 
the leaves of coca. This drug has but recently been 
introduced into medicine, and has become very promi- 
nent on account of its being the strongest local 
anaesthetic known; that is, it deadens the sensibility 
of a simile organ without affecting the others; for ex- 
O O O 7 
ample, if applied to the eye it produces complete in- 
sensibility of the cornea and conjunctiva, which per- 
mits operations to be performed on this delicate organ 
without the aid of chloroform or ether. 
Another remarkable property of this substance is its 
anaesthetic effect upon the mucous membrane. Like 
all narcotics it should be taken or administered with 
great caution; and the effects of its abuse are terrible. 
6. Bromide of Potassium is usually administered to 
restore brain and nerves from the fatigue produced by 
overwork. It too, however, has, like all narcotics, its 
disagreeable features, one of which is its weakening 
influence on the muscles. 
7. Belladonna, and 8, Digitalis. — Both are reme- 
dies for strengthening the heart and the arteries, and 
preventing too free a flow of blood to the brain. 182 
FIRST LESSONS IN PHYSIOLOGY. 
9. Alcohol. — The uses, properties and effects of 
this liquid as a narcotic have been given. 
Tobacco contains a volatile alkaloid called “ nico- 
tine ” which is very poisonous; a drop or two of 
this poison would prove fatal. But the cases of 
“ tobacco poisoning ” by means of nicotine are very 
rare. The mischief done by smoking cigarettes or by 
the excessive use of tobacco is of slow growth and 
effect, but nevertheless sure. To one not used to 
smoking, the effects of a small dose of tobacco are 
well known, viz.: vomiting and vertigo. The effects 
from an excessive use of it are : A tendency to lower the 
general health; to decrease the digestive capacity; 
and to weaken or irritate the nerves and brain. While 
the temperate use of tobacco apparently works no harm 
in adults, this does not argue that it is beneficial to 
them ; and its use by the young should at all times be 
condemned, because to them even a mild use of it is 
hurtful. QUESTIONS. 
16. How is the skeleton divided? 
What is its number of bones ? 
17. Describe the three cavities of 
the skeleton. 
18. What forms the trunk of the 
body ? 
PAGE 16.— 
19. How are the arms attached? 
and how are the movable 
joints fastened together? 
20. How are bones renewed? 
LESSON III.—The Head; Cere- 
bro-Spinal Axis; Teeth. 
page 17.— 
21. Give princ. parts of the head. 
PAGE l8.— 
22. What two cavities in the head ? 
23. What is each a part of? 
page 19.— 
24. What separate tubes do they 
help to form ? 
25. Describe the parts of a tooth? 
PAGE 21.— 
26. Give number and arrangement 
of temporary teeth in, either 
jaw. 
27. Give the same of permanent 
teeth in either jaw. 
28. What sudden changes are in- 
jurious to the teeth; and why? 
29. Mention two great functions of 
bones. 
(X st. Locomotion. 
2d. Protection of softer parts, 
as e. g., the skull protect- 
ing the brain.) 
30 1 low do teeth differ from bones? 
A.—STRUCTURE. 
LESSON I.—Organic and Inor- 
gan) c Matter — Animal 
Structure, 
page 9.— 
1. How are all objects around us 
divided ? 
PAGE 10.— 
2. Upon what is this division 
based ? 
3. How does inorganic matter dif- 
fer from organic as to form ? 
4. How, in respect to coherence ? 
5. How, as to growth ? 
6. How, as to composition ? 
PAGE 12.— 
7. How, as to derivation? 
8. Give the structure of higher 
animals. 
9. Define “Organisms;” “Func- 
tion.” (In Physiology, the 
term Function means office, 
work, or action; the last is 
the preferable.) 
10. State the functions of Organ- 
isms. 
LESSON II.—The Skeleton. 
PAGE 13.— 
11. What effect has intense heat on 
bones ? 
12. How does dilute acid affect 
bones ? 
13. Of what substances are bones 
composed ? 
14. Give the structure of bones. 
TAGE 14 — 
15 How do bones grow ? 184 
FIRST LESSONS IN PHYSIOLOGY. 
LESSON V.—The Trunk, 
page 24.- 
31. Describe the spinal column. 
32. What are vertebrae ? 
33. How are the lungs protected 
from above, and by what are 
they encircled ? 
PAGE 25.— 
34. Describe a vertebra. 
page 26.— 
35. Give three functions of the 
spinal column. 
36. How many ribs are fastened to 
the sternum; and why do the 
other ribs not reach it ? 
37. What lies between each pair of 
vertebrae ? 
38. What two offices have these 
cartilages ? 
39. How is the variation in the 
length of the human body ex- 
plained ? 
40. How is the pelvis formed ? 
LESSON VI.—The Limbs. 
page 27.— 
41. What similarity in the bones of 
the upper and lower limbs ? 
42. Describe the hand. 
PAGE 28.— 
43. Describe the foot. 
44. What supports the body when 
erect ? 
45. State the purpose of the ball- 
and-socket joint. 
46. Where is this joint found? 
47. What is the hinge-joint ? 
48. How many bones in the foot ? 
49. Give the object of the arch of 
the foot ? 
50. State the chief advantages of 
the human hand. 
LESSON VII. — Cartilages — 
The Larynx. 
0 
PAGE 30.— 
51. Give three samples of cartilage? 
52. How does cartilage differ from 
bone ? 
53. Give four uses of cartilage ? 
PAGE 31.— 
54. What, and where, is the glottis? 
55. What is the epiglottis ? 
56. Bound the larynx. 
57. Describe the trachea. 
58. Describe the bronchi and bron- 
chial tubes. 
59. Describe contents of the larynx. 
60. How is sound produced in the 
larynx ? 
LESSON IX.—Muscles; Fat. 
PAGE 35.— 
61. What happens when the fore- 
arm is bent up ? 
62. Describe a muscle. 
63. Why are muscles generally 
called the organs of motion ? 
PAGE 36.— 
64. What is the first property of 
muscles ? 
65. What the second ? 
66. Explain rigor mortis. 
67. How are voluntary muscles dis- 
tinguished from involuntary? 
68. Give two instances of each 
class. 
69. Which class is uncontrolled by 
the will? 
PAGE 37.— 
70. What are the chief uses of fat ? 
LESSON X.—Muscles Motor 
Agents—Walking. 
page 38.— 
71. Show why the arm is consider- 
ed a lever. 
72. To what does the arm owe its 
variety of motions ? 
73. By what are those motions ex- 
erted ? 
page 39.— 
74. Explain why 100 pounds of 
effort is required to balance 5 
pounds at the free end of the 
arm stretched out horizontally. 
page 40. — 
75. In what three forms do we re- 
gain much of the muscular 
force which is apparently lost? 185 
QUESTIONS. 
76. How do muscles generally ter- 
minate ? 
77. Decide the first step in the act 
of walking. 
78. Describe the second step. 
79. Describe the third step. 
80. Describe the fourth step. 
LESSON XI. — Muscles (con- 
tinued)—Work of Muscles 
—Leaping. 
page 42.— 
81. Explain the fatigue in standing 
erect long. 
82. What are the functions ot con- 
nective tissue ? 
page 44.— 
83. Why are the muscles of the 
head and trunk less substan- 
tial? 
84. Where is the helmet ? 
85. Give the number of external 
muscles. 
86. What two motions constitute a 
leap ? 
page 46.— 
87. How is it that a person in leap- 
ing exerts a muscular force of 
twice his weight into the ver- 
tical height ? 
page 47.— 
88. In what way is the mechanical 
power of the body used to 
best advantage ? 
89. How far may we exhaust our 
forces ? 
90. What limits should be observed? 
LESSON XIII.—Skin—Hair and 
Nails—Excretion of Skin. 
page 51.— 
91. How is glue produced from 
skin ? 
92. Describe the parts of the skin. 
93. Describe the epidermis. 
94. What are its main functions ? 
95. What are the main functions of 
the dermis ? 
page 52.— 
96. Describe the dermis. 
97• State the general properties of 
the skin, and give their uses. 
98. Describe the hair and nails. 
99. Describe the two excretions of 
the skin. 
page 53.— 
100. What does the quantity of water 
lost by transpiration depend 
upon ? 
B.—NUTRITION. 
LESSON XIV.—The Blood. 
PAGE 54.— 
101. Describe the clot. 
102. What is the name and the color 
of the liquid ? 
103. What is the composition of 
blood ? 
page 55.— 
104. Give the temperature and spe- 
cific gravity of the blood. 
105. What is the quantity of blood 
in the body ? 
106. What does the health of the 
blood depend upon ? 
107. Describe the red corpuscles. 
page 56.— 
108. Describe the white corpuscles. 
109. What gases does the blood con- 
tain ? 
page 57.— 
no. Give the uses of the blood. 
LESSON XV.—The Circula- 
tion. 1. 
page 58.— 
111. How large is the heart? 
112. How is it that the blood leaves 
the heart and returns to the 
heart again? 
page 59.— 
113. Describe the divisions of the 
heart. 
114. Describe the communication 
between auricle and ventricle? 
page 60.— 
115. Give the course of the blood 
from the heart, and back again 
to its starting place. 186 
FIRST LESSONS IN PHYSIOLOGY. 
116. Which' artery carries venous 
blood ? With what part of the 
heart is it connected ? 
117. Where is the blood rendered 
impure, and to which division 
of the heart does the impure 
blood flow ? 
PAGE 61.— 
118. Mention several helpers which 
assist the action of the heart. 
119. State the functions of each sub- 
division of the heart. 
120. Compare these functions with 
one another. 
LESSON XVI.—The Circula- 
tion. 11. 
page 62.— 
121. How may the movements of the 
heart be examined ? 
122. What movements form a pulsa- 
tion ? 
123. Define systole and diastole. 
What is their ratio of time ? 
PAGE 63.— 
124. What is it that prevents the 
blood, as it leaves the heart, 
from returning at once into 
the veins ? 
125. Describe the auricular systole. 
126. Explain the ventricular systole. 
page 64.— 
127. What is the course of the blood 
on leaving the ventricles ? 
page 65.— 
128. What two effects has the pres- 
sure of the three ounces of 
blood passing into the arteries 
after each ventricular systole ? 
page 66.— 
129. What is the pulse? Where may 
it be felt ? Why are the capil- 
laries pulseless ? 
page 67, 68.— 
130. Give the use of the arteries ? 
And state two reasons why 
compression of veins does not 
check the circulation. 
LESSON XVIII.—The Lungs. 
PAGE 74.— 
131. Define arterial and venous 
blood. How do they differ 
from each other ? 
132. How, and where, is venous 
blood converted into arterial? 
page 75.— 
133. Locate and describe the lungs. 
134. Give the structure of the trachea, 
bronchial tubes and the finer 
tubes. 
135. How many lobes in each lung? 
What is a lobule ? 
136. What becomes of the finer 
bronchial tubes? 
137. Describe the air-cells and their 
contents. 
page 77.— 
138. What is the purpose of the capil- 
laries of the lungs, and how 
is it accomplished ? 
139. What does venous blood gain 
and lose in the lungs? By 
what means is its purification 
effected ? 
page 7g.— 
140. What is accomplished by inspir- 
ation and expiration ? What 
are the most powerful aids in 
this process. 
LESSON XIX.—Respiration, 
page 79.— 
141. Describe the process of inspira- 
tion. 
142. Describe expiration. 
143. Explain the widening and 
lengthening of the chest dur- 
ing ordinary inspiration. What 
are the helps in very deep in- 
spiration ? 
PAGE 81.— 
144. What rhythm is observable in 
inspiration, and to what is it 
similar ? 
145. Give the points in which inspir- 
ed air differs from expired. 
146. Explain the absorption of oxy- 
gen by venous blood. QUESTIONS. 
187 
147. What does the oxygen combine 
with, and what becomes of 
this combination finally ? 
PAGE 8l.— 
148. Why is fresh air necessary, and 
why ventilation ? How does 
a lack of either shorten life ? 
PAGE 82.— 
149. Explain coughing, sneezing 
and sighing; also, laughing, 
sobbing and snoring. 
.150. Compare the lungs with the 
heart, giving three points in 
common and three points of 
difference. 
DESSON XXL—Air and its 
Relation to the Body. i. 
page 87.— 
151. Explain the requirement of the 
body in regard to vital heat. 
152. What penalty attaches to the 
decrease of the normal tem- 
perature? What to the in- 
crease of the normal tempe- 
rature ? 
page 88.— 
153. In what ways do we experience 
losses of heat ? 
154. Define conduction of heat. 
page 89.— 
155. Show that water conducts heat 
better than air. 
page 90.— 
*56. Define radiation of heat. State 
how a person may expose him- 
self to partial radiation, and 
what the effects may be. 
157. Explain the feeling of cold in, 
windy weather. 
158. In what way are bodies affected 
by conduction and radiation 
of heat ? 
page 91.— 
159. What explains the loss of heat 
by evaporation ? 
360. To what are the injurious effects 
of wet feet ascribed ? How 
should we guard against cold ? 
LESSON XXII.—Air and its 
Relation to the Body. ii. 
page 92.— 
161. Describe the functions of our 
garments. 
162. Why is flannel a healthier ma- 
terial than india-rubber? 
page 93.— 
163. What is the first object of cloth- 
ing? What the second? 
164. Give the characteristics of linen. 
Why is it to be avoided next 
to the skin ? 
page 94.— 
165. How does cotton differ from 
linen ? 
166. Give the characteristics of wool- 
lens. What makes woollen 
goods valuable as clothing 
material ? 
PAGE 95.— 
167. Explain why the bed should be 
warmer than the clothing. 
PAGE 96.— 
168. State why moist walls are un- 
healthy. IIow is their moisture 
removed best ? 
169. What does the purity of air 
depend on ? What causes the 
impurity of air? 
PAGE 97.— 
170. Distinguish between ventilation 
and draught. What does ven- 
tilation depend on ? 
LESSON XXIV.—Food. 
PAGE IOI.— 
171. What are the principal elements 
composing the human body? 
PAGE 102.— 
172. What are the sources of loss to 
the body ? 
173. Illustrate this by a man in a 
glass house. 
PAGE 103.— 
174. Define food. 
175. How are the materials which 
constitute food divided ? 
176. What mixture of these divisions 
is essential to our well-being ? 188 
PIRST LESSONS IN PHYSIOLOGY. 
PAGE 104,— 
177. Mention two substances that 
are nutritious but not digest- 
ible. 
178. Why are many tasteless sub- 
stances not nutritious ? How 
may they be rendered nutri- 
tious. 
179. State the purpose of cooking 
our food. 
180. What sensations remind us of 
the necessity of taking food? 
What is meant by oxygen- 
starvation ? 
PAGE I07.— 
194. Through what channel does 
food pass into the blood ? 
195. What is the daily quantity of 
solid food of a man ? 
196. What two important additions 
should be made to this ? 
197. When does digestion commence? 
198. In what consists the first part 
of digestion ? 
199. What purpose do the teeth in. 
fishes subserve? 
PAGE 108.— 
200. Describe the characteristic teeth 
of the herbivores. 
201. Describe teeth of carnivores. 
202. What significant arrangement 
in the human teeth ? 
203. What is the function of the 
tongue in digestion? 
204. What organs combine to break 
down the food ? 
205. Why is it broken down ? 
206. Why is rapid eating injurious? 
PAGE 109.— 
207. Describe the second part of the 
digestive process. 
208. State the function of the saliva ? 
209. When does deglutition take 
place, and how is it effected ? 
210. Why may a starving sheep be 
rightly said to be carnivorous 
(See pages 102 and 119.) 
LESSON XXVI.—Digestion, ir. 
page 110.— 
211. Describe the stomach. What 
name is given to its two open- 
ings, and where are they sit- 
uated ? 
PAGE III.— 
212. In what way is the food in the 
stomach reduced to chyme, 
and what fluid assists in this 
operation ? 
213. Which kind of muscles perform: 
mechanical labor in the stom - 
ach ? 
214. Why cannot the stomach crush 
an entire grape ? 
SOLID AND LIQUID FOOD 
(181.—Fine Print—State the advan- 
tages of beef. 
182. How does veal compare with 
beef? 
183. How does mutton compare with 
beef? 
184. What are the advantages and 
disadvantages of pork ? 
185. What part should fish play in 
meals ? 
186. Give the object of eating butter. 
PAGE 105.- 
187. State the excellencies of wheat. 
188. How does the potato compare 
with bread? 
189. Which is, after all, the most 
important of all foods, and 
why ? What constitutes im- 
pure water? 
190. What is remarkable about milk? 
Why are coffee and tea highly 
valued ?) 
LESSON XXV.—Digestion, i. 
PAGE 106.— 
191. Whence do plants derive their 
food? 
192. What do animals generally feed 
on? What great distinction 
between animals and plants 
respecting their food? 
193. Describe the changes wrought 
upon the food in the body. QUESTIONS. 
189 
215. State the chief functions of the 
stomach. 
216. What action is temporarily 
suspended in the stomach ? 
217. Give the conditions favorable 
to stomach-digestion. 
218. Why may ice-water taken dur- 
ing a meal prove injurious ? 
219. Give the desirable length of the 
interval between two consecu- 
tive meals. 
220. State the process undergone by 
the food between the mouth 
and the pylorus. 
LESSON XXVII.-Digestion. hi. 
PAGE 113.— 
221. Describe the intestines. 
222. How are they divided? 
223. State the length of the small 
intestine, and of the entire 
alim. canal. 
224. Where does the peristaltic mo- 
tion take place, and what does 
it consist in ? 
PAGE 115.— 
225. How is the large intestine 
divided ? 
226. Describe the position of each 
part. 
227. How is the large intestine 
readily recognized ? 
228. How does the motion of the 
large intestine differ from that 
of the small ? 
229. Mention all the digestive fluids. 
.page 116.— 
230. What is the purpose of the mu- 
cous substance secreted by 
the stomach ? 
231. Describe the other liquid se- 
creted by the stomach. 
232. What action has this liquid upon 
fatty substances ? 
233. Explain the pernicious effect 
upon the stomach of immode- 
rate quantities of alcohol. 
234. What two actions convert the 
food into chyme ? 
235. What becomes of the chyme 
after leaving the stomach ? 
236. Where does the food undergo 
its most important change ? 
237. Describe the liver. 
238. What are the functions of the 
liver ? 
239. Where does the bile accumulate, 
and whither does it flow ? 
page 117.— 
240. Why must the bile be con- 
ducted out of the system ? 
241. What does bile produce when 
in the blood ? 
242. What does bile produce when 
thrown into the stomach ? 
243. What name has the chyme after 
its union with bile? 
244. Give the remaining two actions 
of the bile. 
245. State the composition of the 
chyme when leaving the stom- 
ach. 
page 118.— 
246. What distinguishes the pan- 
creatic juice? 
247. Describe the pancreas, and the 
peculiarity it has in common 
with the salivary glands of the 
mouth. 
248. What is the office of the intes- 
tinal juice? Where is it se- 
creted ? 
249. What is the estimated quantity 
of the five digestive liquids a 
day? What of the gastric 
juice alone? 
250. Describe the combined action 
of five liquids. 
LESSON XXVIII-Assimilation. 
PAGE 119.— 
251. Explain the interdependency of 
life and death in the organism. 
PAGE 120.-- 
252. How is digested aliment con- 
verted into blood so as to be 
distributed over the entire 
body ? 
253. Describe the twofold object of 
absorption. 190 
FIKST LESSONS IN PHYSIOLOGY. 
PAGE 122.— 
254. Describe blood-vessels or capil- 
laries (Fig. 26). Describe 
the lacteals (Fig. 27). 
255. Describe the absorption of the 
chyle by blood-vessels. 
256. Describe the absorption by the 
lacteals. 
257. Explain the absorption of chyle 
by a villus. 
PAGE I23.— 
258. Describe the lymphatic glands. 
page 124.— 
259. Describe the position aud action 
of the thoracic duct. 
260. Trace the further progress of 
the chyle. 
C.—INNERVATION. 
LESSON XXX.—The Nervous 
System, i. 
page 130.— 
261. Give the first two functions of 
the nervous system, demon- 
strating each. 
PAGE I3I.— 
262. Give the third, fourth and fifth 
functions, demonstrating each; 
263. Give sixth and seventh func- 
tions, and demonstrate each. 
PAGE 132.— 
264. How is the nervous system div- 
ided and subdivided ? 
PAGE I33.— 
265. Describe the brain. 
page 134.— 
266. Describe the cerebrum and 
cerebellum. 
267. Describe the spinal cord. 
268. Where do the cerebro-spinal 
nerves originate? What is 
their form ? 
269. Describe nervous fibres. Where 
do they originate ? 
270. What do nervous fibres form at 
their termination? 
271. What is the size of those nerv- 
ous fibres, and where are they 
smallest ? 
PAGE 135.— 
272. What does the sympathetic sys- 
tem consist of ? 
273. Where is it situated, and how 
is it connected ? 
274. What course is pursued by its 
nerves ? 
PAGE 136.— 
275. Mention the two substances 
composing the nervous sys- 
tem. 
276. Where is the white substance 
within the gray, and where 
the gray within the white ? 
277. Of which substance are the nerv- 
ous fibres and tubes ? Of 
which the cells ? 
278. Which substance forms the cen- 
tral organ of the nervous sys- 
tem ? 
279. What function has the gray- 
substance ? What function the 
white ? 
280. To what may both materials be 
compared ? 
LESSON XXXI.—The Nervous 
System, ii. 
page 137.— 
281. Explain the reason for the con. 
volutions in the brain. 
page 138.— 
282. What seems to be the function 
of the cerebral hemispheres ? 
and what are the reasons for 
believing this ? 
page 139.— 
283. State the function of the medul- 
la oblongata. 
284. In what respect is the medulla 
obi. specially distinct from the 
brain and the spinal cord? 
285. Give the functions of the spinal 
cord. 
page 140.— 
286. Describe the functions of the 
sympathetic system. 
287. Explain the two special func- 
tions of the nerves. 191 
QUESTIONS. 
288. Demonstrate the existence of 
motor nerves. 
page 141.— 
289. Demonstrate the existence of 
sensory nerves. 
290. What are the nerves of the 
spinal cord endowed with ? 
LESSON XXXIII.—The Senses. 
PAGE I44.— 
291. Define sensory organs. 
292. What is sensation? Show by 
an example. 
page 145.— 
293. Distinguish between objective 
and subjective sensations. 
294. Explain in what manner the 
sense of sight is produced. 
295. How are sensations generally 
produced, and what becomes 
of them ? 
Touch. 
page 146.— 
296. Give the common sensations 
excited by the sense of touch. 
297. In what does its distinct struc- 
ture exist ? 
298. Show by facts that an excess of 
heat or cold produces like 
impressions. 
page 147.— 
299. How far do the nerves retain 
their sensibility to touch? 
300. State why this sense seems cap- 
able of great improvement. 
LESSON XXXIV.—Taste. 
PAGE I48.— 
301. Give the most frequent sensa- 
tions excited by the sense of 
taste. 
302. In what does the distinct struc- 
ture of this sense consist ? 
303. What tends greatly to modify 
the sense of taste ? And what 
is remarkable about the ton- 
gue? 
304. How can it be proved that this 
sense is largely connected with 
other senses ? 
PAGE I49.— 
305. Give the principal sensations 
produced by the sense of 
smell. 
306. Describe its structure. 
307. How are the nasal chambers 
protected from dryness ? 
308. W hat form must all matter have 
in order to impress itself, 
upon the olfactory nerves ? 
309. How does a dog obtain the 
scent of an object? 
310. State what connection there is, 
if any, between bad odors and 
their supposed effects ? 
LESSON XXXV.—Sight, i. 
PAGE I50.— 
311. State the principal sensations 
excited by the sense of sight. 
312. Describe the structure of this 
sense. 
.313. What does the eye-ball owe to 
the membrane which covers 
it, and of what does the eye- 
ball consist? 
314. Describe the choroid. 
page 151.— 
315. Describe the iris, 
page 152.— 
316. Describe the retina. 
317. How may the blind spot in the 
eye be readily detected ? 
318. What do we experience when 
the retina is in a state of utter 
rest? 
page 153.— 
319. Describe the optical apparatus 
of the eye. 
320. What functions have the eye- 
brows and eye-lids ? And how 
is the mobility of the eye-ball 
effected ? 
LESSON XXXVI.—Sight, ii. 
page 154.— 
321. Describe a camera obscura, and 
the principle of photography. 
Smell. 192 
FIRST LESSONS IN PHYSIOLOGY. 
322. Show that the eye may be com- 
pared to a camera obscura. 
PAGE 155 — 
323. What is the experiment that 
proves that the eye can adjust 
itself to different distances. 
PAGE 156.— 
324. Describe the distance of distinct 
vision. 
325. Explain short-sightedness and 
long-sightedness,and tell how 
each may be neutralized. 
PAGE 157- — 
326. Explain visible direction. 
PAGE 158.— 
327. What is known regarding the 
duration of impressions on 
the retina? 
328. What is color-blindness? 
329. How may the sensitiveness of 
the retina be ascertained? 
330. Mention two frequent sources 
of injury to the eye. 
LESSON XXXVII.—Hearing. 
PAGE 159.— 
331. What are the principal sensa- 
tions derived from the sense 
of hearing ? 
PAGE 160.— 
332. Give the general structure of 
this sense. 
333. Describe the outer ear. 
334. Describe the external tube and 
the drum of the middle ear. 
335. Describe the contents of the 
drum. 
336. What seems to be the function 
of the eustachian tube ? 
PAGE 161.— 
337. Describe the labyrinth. 
PAGE 162.— 
338. State how the sensation of 
sound is produced. 
339. Compare the ear with the eye, 
givingthreepointsincommon. 
(1. Outer ear and ext. tube— 
opt. apparatus. 
2. Tympanum—retina. 
3. Auditory nerve — optic 
nerve.) 
340. Find three points of difference. 
LESSON XXXIX.—The Mind. 
PAGE l66.— 
341. Describe the two apparatus of 
life. 
PAGE 167.— 
342. State the difference between 
the higher animals and man, 
as regards domestication, 
education and the conscious- 
ness of the infinite. 
343. What specially characterizes 
the human species, at least 
the higher types of man ? 
page 168.— 
344. Give proofs of the dependence 
of the mind on the body. 
345. Give proofs of the dependence 
of the body on the mind. 
346. When is a person said to be 
attentive ? 
PAGE 169.— 
347. Demonstrate, by examples,that 
there is an inward and an out- 
ward attention. 
348. Define sensation and percep- 
tion. 
PAGE 170.— 
349. Define idea. 
PAGE 171.— 
350. Define physiology. 
LESSON XL. —Alcohol—Stimulants—Narcotics. 
page 172.— 
351. State prop, and uses of alcohol. 
352. Give general effects of stimu- 
lants. 
353. What is a stimulant? 
354. Give effects of small and large 
doses of alcohol or stimulants. 
355. Mention three special effects 
of alcohol. 
356. Describe 3 effects of the ex- 
cessive use of alcohol. 
357. State 5 important narcotics 
their uses and effects. , 
358. Give effect of excessive use 01 
tobacco. 
359. State effect and use of coffee 
and tea. GLOSSARY, 
CONTAINING TEE ANATOMICAL AND PHYSIOLOGICAL MEANING OF 
CERTAIN TERMS. 
Ab-do'men. The largest cavity of the body; below the dia- 
phragm and above the pelvis, containing the stomach, 
intestines, liver, spleen, etc. 
Ac'id. A substance generally sour to the taste, which 
changes vegetable blue colors to red, and combines 
with bases to form salts. 
Adipose'. Fat, or fatty. 
Albu'men. A substance like the white of an egg, coagu- 
lating by heat. 
Alcohol. A result of the formation of sugar. 
Al’i-ment. Nourishment; food. 
Al-i-ment'a-ry Ca-nal. A tube passing through the body, 
beginning with the mouth, piercing the diaphragm, and 
terminating with the rectum, by which nourishment is 
taken into the body, digested, and indigestibles excreted. 
Aor'ta. The great artery arising from the upper and the 
back part of the left ventricle of the heart; the common 
trunk of the arteries of the body. 
(Physiol.) A system of organs concerned in 
, oome special function of the animal body. 
Arac. Product of the distillation of rice or palm-juice. 194 
FIRST LESSONS IN PHYSIOLOGY. 
Ar'tery. Any branch of the aorta conveying blood in the 
direction from the heart to all parts of the body. 
As-sim-i-la'tion. The conversion of food into the substance 
of organized beings. 
Au'ricle. The external ear. Hence one of the two venous 
chambers of the heart, resembling the external ear. 
Beer. A fermented liquid made from any malted grain, 
with the addition of hops or other substances. 
Bi'ceps. Two-headed. A muscle attached to the shoulder- 
bone, connecting it with one of the bones of the fore- 
arm. 
Bicus'pid. A molar tooth having two points. 
Brandy. A result of the distillation of strong wines. 
Bronchus. The windpipe, or trachea. The bronchi, or 
bronchia, now mean the two tubes which arise from the 
bifurcation of the trachea, and carry air into the lungs. 
Cognac. A result of the distillation of strong wines. 
Cam'era-obscu'ra. An instrument used in a darkened room 
to throw images of external objects upon a surface. 
Ca-nine'. Applied to teeth, it means the pointed tooth 
next to the incisor. It is often quite long. 
Cap'-il-la-ries. A net-work of minute blood-vessels, con- 
necting the termination of the arteries with the termi- 
nation of the veins. 
Car'di-ac. From the Greek kardia, the heart. 
Carnivorous. Flesh-eating. Camivore, a carnivorous animal. 
Car'ti-lage, or gristle. A dense, firm substance of less 
hard tissue than bones. 
Cell. A small, distinct, spheroidal mass of protoplasm or 
living material. 
Cer-e-bel'lum. The little brain, beneath the cerebrum. 
Cer'e-brnm. The brain proper, occupying the entire upper 
portion of the skull. GLOSSARY. 
Cho'roid. A coat containing a great many blood-vessels, 
lining the interior surface of the sclerotic coat of the eye. 
Chyle. A milky fluid formed in the process of digestion by 
the action of the pancreatic juice and the bile on the 
chyme in the duodenum. 
Chyme. A pulp formed by the action of the stomach on 
the food. 
Cil'i-ary Processes. The minute radiating ridges formed 
around the iris by the anterior portion of the choroid. 
Clav'i-cle. The collar bone. 
Coch'lea. A cavity of the ear resembling a spiral shell. 
Coherence. The act or state of cohering. 
Co'lon. That portion of the large intestine extending from 
the caecum to the rectum. 
Connective tissue. The connecting medium by which the 
different parts of the body are held together. It passes 
from the dermis between all the other organs, ensheatli- 
ing the muscles, coating the bones and cartilages, and 
ultimately entering into the mucuous membranes. 
ContraCtile. Having the power of contraction. 
Corpus'cle. Minute body or particle of matter. 
Cu'ti-cle. The superficial layer of the skin. The same as 
epidermis. 
Cutis. The deeper portion of the skin. The same as dermis. 
Degluti'tion. The act, or power, of swallowing food. 
Delirium Tremens. Usually the result of continuous in- 
toxication. 
Dentine. The principal constituent of a tooth. 
Deriva'cion. Transmission of anything from its source. 
Dermis. The same as cutis. (See this.) 
Diaphragm. The muscular partition separating the chest 
from the abdomen, and assisting respiration. 
Dias'tole. A dilatation of the heart and arteries; opposed 
to systole. 196 
FIRST LESSONS IN PHYSIOLOGY. 
Digestibility. The quality of being digestible. 
Dilatation. Expansion. 
Duodenum. The first of the small intestines; is about 
as long as the breadth of twelve fingers. 
Enam'el. The hard exterior surface of the teeth. 
Epidermis. The same as cuticle. (See this.) 
Epiglot'tis. A cover on the aperture of the windpipe. 
Eu-sta'chi-an Tube. A tube extending from the inner side 
of the tympanum, opening at the back of the nostrils. 
Fetor. A strong, offensive smell. 
Fi'brine or fibrin. A white, tough, fibrous substance, ob- 
tained from coagulated blood. 
Function. Performance, office work, action. (SeeQues. 9.) 
Oan'gli-on, pi. ganglia. A mass of nerve-cells, forming a 
center from which nervous fibres radiate. 
Gas'tric. Belonging to the stomach. 
Glot'tis. Aperture at the top of the larynx. 
Hem’or-rhage. Loss of blood; bleeding. [imal. 
Herbiv'orous. Feeding of plants. Herbivore, herb-eating an- 
Hy'gi-ene. The knowledge of the preservation of health. 
ll'eo-jeju'num. The part of the small intestine immediately 
succeeding the duodenum. 
Incis'ors. The four front teeth of both jaws. 
Innervation. The function of the nervous system. 
Inorgan'ic. Destitute of organs or animation. 
In-sal-i-va'tion. The mixing of food with saliva. 
Fris. A membrane with an aperture in the center, stretched 
vertically across the eye, and separating the anterior 
from the posterior chamber. It gives the eye its color. 
Lab'y-rinth. The internal ear. 
Lac'te-al. A lymphatic vessel of the intestinal canal. 
(See Lymphatic.) 197 
GLOSSARY. 
Lar'ynx. Cavity at the top of the trachea, the organ of 
voice. 
Lever. A stiff bar or rod, which turns on, or is supported 
in, a fixed point. 
Lig'a-ment. A strong fibrous material, uniting bones or 
other solid parts together. 
Liquors. Highly flavored liquids containing large quantities 
of alcohol and sugar. 
Lymphat'ic. Vessel conveying a colorless, watery fluid, 
called lymph, to the thoracic duct. 
Mas-ti-ca'tion. The act of chewing. 
Me-dul'la Ob-lon-ga'ta. “ The oblong marrow.” Portion 
of the nervous cord within the skull nearest to the 
spinal cord. 
Mem'brane. A thin layer of tissue, serving to separate, 
cover, or envelop other organs. 
Mo'lar. A grinding tooth. 
Mo'tor. Giving motion. 
Mu'cous Mem'brane, or Mucous Coat. The continuation of 
the skin, in apertures and interior cavities: that is, the 
lining of the internal cavities. 
Mu'cus. A more or less tenacious fluid. 
Narcotics. Remedies inducing sleep or insensibility. 
Nutri'tion. The conversion of food into nutriment. Some- 
times used to comprise digestion, absorption, respira- 
tion, circulation and assimilation. 
CE-soph'a-gus. The tube which extends from the interior 
portion of the pharynx to the stomach; the gullet. 
Organ'ic. Having organs, animation; or, pertaining to 
organs. Hence, organism=*an organic being. 
Ossification. The formation of bone. 
Pal'ate. The roof of the mouth. 198 
FIRST LESSONS IN PHYSIOLOGY. 
Pancreas, or “ sweet-bread.” A gland of the abdomen, 
under and behind the stomach, at the right of the spleen. 
Pel'vis. Two separate bones to which the legs are attached, 
and which bound the abdomen below. 
Phys-i-oVo-gy. The science of the functions of animals and 
vegetables. Human physiology is the science which 
treats of the functions of the human body and the 
manner in which they are brought about. 
Proc'ess. Eminence of a bone; a portion prolonged 
beyond others with which it is connected. 
Pul'mo-na-ry. Pertaining to or affecting the lungs. 
Py-lo'rus. The lower or right orifice of the stomach. 
Ret'i-na. A very delicate membrane, lining the hinder 
two-thirds of the eye-ball. It is the continuation 
of the optic nerve. 
Rhythm. A measure of anything according to the number 
of regularly occurring impulses. 
Rigor Mortis. Stiffness of the entire body after death. 
Rum. Product of distillation of fermented sugar cane. 
Sa'crum. The triangular bone forming the posterior part of 
the pelvis, and terminating the vertebral column. It is 
a union of the 25th, 26th, 27th, 28th and 29th vertibrae 
into one great bone. 
Sa-li'va. A thin watery liquid of the mouth, having the 
property of converting starch into sugar. 
Sapicl'ity. The quality of bodies that gives them taste. 
Scle-rot'ic. The white of the eye. A tough, firm spheroi- 
dal case, the greater part of which is white and opaque. 
Se-cre'tion. The separation of substances from the blood 
of animals, or from the juice of plants. 
SensibiVity. The power which any tissue of the body has 
of causing changes inherent or excited on it to be per- 
ceived and recognized by the mind. GLOSSARY. 
199 
JSe'rum. Watery part of animal fluids, as of blood or 
milk. 
Skel'e-ton. The solid framework of the body of an animal. 
Stimulant. Means of increasing the vitality of some organ 
or of the human system. 
Sympathetic. A long double series of ganglia connected 
together by nervous cords. 
Sys'to-le. The contraction of the heart—opposed to dias- 
tole. 
Tac'tile. Perceptible to, or susceptible of, touch. 
Tem'perature. The amount of heat which a body may com- 
municate to other bodies. 
Ten'don. A white cord attached at one end to a bone and 
at the other end to a muscle; the same as sinew. 
Tho'rax. The chest; the part of the body between the 
neck and the abdomen. 
Thorac'ic. Pertaining to the thorax. 
Tis'sue. A membranous organization of parts. 
Tra'chea, or Trach'ea. A tube strengthened by cartilagi- 
nous rings extending from the larynx downward along 
the front part of the thorax, and passing into the thorax 
where it divides into two branches, a right and a left, 
called the bronchi. 
Tym'pa-num, or Drum. Cavity of the middle ear, sepa- 
rated from the external ear by the tympanic membrane. 
Vein. A vessel to convey venous blood to the heart. 
Ven'tricle. Generally applied to the two cavities of the 
heart which communicate with the auricles. Applied 
also to other cavities in the body. 
Ver'te-bra, pi. Vertebrae. One of the bones composing the 
vertebral column. It consists of a main part, called 
the body of the vertebra; and of seven projections, 
called processes. 200 
FIRST LESSONS IN PHYSIOLOGY. 
Vil'li. Soft projections or processes covering certain mem- 
branes. 
Vit're-ous Humor. The transparent mass which fills the eye 
behind the crystalline lens. 
Wine. Fermented juice of the grape. 
Whisky. Product of distilling wheat, rye or corn. INDEX. 
PAGE. 
Absorption 120 
Accommodation of the Eye. 154 
Adipose tissue 36 
Air, and its relation to the 
body 87, 92 
Alcohol 172 
“ special effects 174 
“ effects of exc. use.. 176 
Alcoholic insanity 178 
Alimentary canal 19, 113 
Animal structure 12 
Animal apparatus of life... 166 
Aqueous humor 153 
Arac 175 
Arch of the foot 28 
Arrangement of teeth 21 
Arteries 64, 67 
Attent:on 168 
Auricles 59, 61 
Back-bone 24 
Ball and socket-joint 28 
Bed 95 
Beer 175 
Belladonna 181 
Biceps 35 
Bicuspid 20 
Bile 116 
Blood — Action of 63 
Circulation .... 58, 62 
Composition 54 
Corpuscles 56 
Quantity 55 
Sounds 66 
Spec, gravity 55 
Uses 57 
PAGE. 
Bones 13 
Bones of the head 17 
Brain 132, 137 
Brandy 175 
Bromide of Potassium.... 181 
Butter 105 
Canines 20 
Capillaries 65, 66, 77 
Carbonic acid gas 11, 77 
Cartilages.... 14, 18, 26, 30, 80 
Chloral 181 
Chloroform 180 
Chocolate •••• 182 
Chyle 117, 119 
Chyme 117, 119 
Choroid 150 
Cheek-bone 18 
Chest 16 
Cells, cellular tissue 16 
Cells of air in lungs 77 
Center of ossification 14 
Cerebellum 138 
Cerebro-spinal axis 18, 134 
Circulation 58, 62 
Clot 54 
Clothing 92 
Cocoaine 181 
Coffee 105, 182 
Cognac 175 
Coherence 10 
Collar-bone 16, 24 
Composition 11 
Composition of bones 13 
Conduction of heat 88 
Contractility 35 202 
INDEX. 
PAGE. 
Corpuscles, of blood 55 
Corpuscles of touch 51 
Cotton 94 
Coughing 81 
Crystalline lens 153 
Delirium Tremens. 174, 177 
Dentine 20 
Dermis . 51 
Digestibility 103 
Digestion 107, 110, 111, 113 
Digestive Fluids 115, 118 
Digitalis 181 
Direction, visible 157 
Distinct Vision 156 
Draught 97 
Drum 160 
Duration of impr. on retina 158 
Ear 159 
Enamel 20 
Epidermis 51 
Epiglottis 30 
Evaporation 90 
Eye-ball 150 
Eye-tooth. 20 
Expiration 78, 79 
Fangs 19 
Fat 36 
Fibrine 54 
Fish 104 
Food 12, 104, 105, 106, 107 
Foot 27 
Form 10 
Formula for teeth 21 
Frontal bone 17 
Gastric juice 116 
Glossary of words 191 
Glottis 30 
Glue 51 
Grinders 21 
Gristle 14 
Growth 11 
Growth of bones., 14 
PAGE. 
Hair 52 
Hand 27 
Haunch-bone 24 
Head 17 
Hearing, sense of 159 
Heart 12,58,59,61, 83 
Hinge-joint 28 
Hunger 104 
Hydrogen 101 
Ideas 170 
Incisors 20 
Ingredients of bones 13 
Innervation 132 
Inorganic matter 9, 11 
Insalivation 109 
Intoxication 176 
Inspiration 78, 79 
Intestinal juice 118 
Intestines..... 113, 115 
Involuntary muscles 36 
Iris 151 
Irregularity in diet 104 
Insanity 138 
Jaw, upper and lower 18 
Knee-pan 28 
Labyrinth 161 
Larynx 30 
Laughing 82 
Leaping 46 
Lever 39 
Ligaments 29 
Limbs 15, 27 
Linen 94 
Liquors 175 
Lobes 75 
Lobules 76 
Long-sightedness 156 
Lungs 74, 83 
Lymphatic glands 123 INDEX. 
203 
FAGE. 
Marrow 13 
Milk 105 
Mind 168 
Medulla oblongata 139 
Molars 21 
Muscles 12,35,36, 38, 42 
Mutton 104 
Nails 52 
Narcotics 180 
Neck of teeth 19 
Nervous fibres..12,133,134, 140 
“ matter 12 
*' system, 130, 136,137, 140 
Nitrogen 80, 87, 101 
Nose-bone 18 
Occipital bone 18 
Opium 180 
Optic apparatus 153 
Organic matter 9, 11 
Organic apparatus of life.. 166 
Organism 11, 12 
Oxygen 12, 80, 87, 101, 103 
Pancreatic juice 117 
Papillae 146 
Pelvis 16, 24, 26 
Perception 169 
Peristaltic motion 113 
Perspiration 52 
Physiology, definitions of.. 171 
Pork 104 
Potatoes 105 
Processes 25 
Pulse 66 
Questions 183 
Radiation of heat 89 
Requirements of health.. 
26, 55, 82, 88 
Respiration 12 
“ by the skin 82 
Retina 152 
PAGE. 
Rhythm of the heart. 63 
“ of respiration .... 79 
Ribs 25 
Rigor-mortis 36 
Rum 175 
Sacrum 26 
Sclerotic 150 
Secretiou 52 
Sensation 144, ]70 
Sensibility 36 
Sensitiveness of retina 158 
Sensory Organs 144 
Serum 54 
Short-sightedness 157 
Shoulder blade 16, 25 
Side-bone 17 
Sighing 82 
Sight 150 
Skeleton 14 
Skull 14,18, 24 
Smell, sense of 148 
Sneezing 82 
Snoring 82 
Sobbing 82 
Sounds 159, 162 
Sphenoid-bone 18 
Spinal cord 25, 134, 139 
Sternum 24 
Stimulant 173 
Stimulants 178 
Stomach 110, 111 
Structure of higher animals 12 
“ of bones • • 13 
Sulphuric ether 180 
Sympathetic system.... 135, 140 
Taste, sense of 148 
Tea 105, 182 
Teeth 19 
Temperature of body 88 
Temporal bone 17 
Tendons 40 
Thirst 104 
Thoracic duct 124 
Thorax 16 
Thought 170 204 
INDEX. 
PAGE. 
Tobacco 182 
Touch corpuscles 61 
Touch, sense of 146 
Trachea 31 
Trunk 15, 24 
Tympanum ICO 
Veins 67, 77 
Ventilation.., 81, 96 
Ventricles 59, 61 
Vertebrae 18,24, 25 
PAGE.. 
Vision 150,154, 15ft 
Voluntary Muscles 3fr 
Walking 4fr 
W aste-materials 12, 102 
Water 105 
Wheat 105 
Whisky 175 
Windpipe 31 
Wine 17a 
Woolen 94 
Work ..44, 4T