WW? m^ ^K V4' SHU.'- as? "Ill rii-c- &*: ]*':■■! i£:.' ':rr. l^U] ; P' &■ P RI N C IP L E S 0 F M E I) I 0 I N E. AN KLKMKXTAIIY VIl-AV OF THE CAUSES, KATT'RE, TREATMENT. DIAGNOSIS AND FROCXOSIS OF I^EASE. .". 4 PRINCIPLES OF MEDICINE. AN ELEMENTARY MEW AUSES. NATURE, TREATMENT, DIAGNOSIS ANL PROGNOSIS DISEASE. WITH BRIEF REMARKS ON HYGIENICS, OR THE PRESERYATION OF HEALTH. CHARLES J. B. WILLIAMS, M.D., F.R.S. A XEW AMKKK'AN FROM THE THIRD AND REVISED LONDON EDITION > v> LIBRARY SUMEOHOCNCtULS Of f ICE PinLAEELHft-T! '■....." " LANCHARD & L KA. 18 5 7. 1857 v i ? ■sA'OiriA.fcv.irvf*^ 1 K k.< PREFACE, In this work the attempt is made to place the practice of Medicine on v looting somewhat corresponding with that of Physiology, Chemistry, and other sciences which equally depend on the accurate observation and rational arrangement of facts. If our knowledge of the healthy body, and of its parts and functions, be exact, it ought to be our best guide in the study of the same parts and functions in a state of disease. Yet the habit has long prevailed, and even still has its avowed advocates, of regarding the phenomena of disease as a new and separate order of things, the character and laws of which are to be investigated by themselves, and without reference to the standard of health from which they deviate; as if diseases were independent entities, and as if the body under their influence ceased to possess the same structures and functions which it has in health. Happily, however, such irrational dogmas do not now find much favour with the members of our profession, who, in proportion as they become more enlightened by sound physiology, recognise in it, when combined with careful clinical and pathological observation, the best guide to the understanding and treatment of disease. It must be admitted that there remain considerable doubt and obscurity in many subjects, both in Physiology and in Medicine, and the science of one and the art of the other must, therefore, still be acknowledged to be imperfect; but no one can dispassionately look back on the progress which has been made in both departments within the last thirty years, without being encouraged to hope for increasing precision in the science and greater success in the art. For an additional proof of the existence of a growing interest and confidence in rational medicine, I may perhaps be excused in referring to the success of the former editions of this work. When first I communicated to my publisher my intention of bringing out a work on the Principles of Medicine, I was by no means encouraged by the intimation that books on that subject did not VI PREFACE. sell; but no sooner was it discovered that the "Principles" were essentially and intelligibly practical, than the demand for the work became sufficient to exhaust two editions, long before I could find time to replace them. Several editions have also appeared on the Continent and in America. I have now to express my regret that the incessant engagements of my practice have so long delayed the appearance of this edition. In fact, it might have been deferred much longer, if I had not secured the valuable assistance of my friend and former pupil, Dr. R. J. Mann, who has contributed several articles on recent investigations in Physiology and Animal Chemistry, and has taken great pains in revising the composition of the whole work. To my friend, Mr. George Gulliver, I am also indebted for looking over the chapters on Diseases of the Blood and Inflammation, and for very important micro- scopic contributions on these subjects. Free reference has been made to va- rious recent authors on Physiology and Pathology; but I would especially mention the works of Dr. Carpenter, Mr. Paget and Professor Rokitansky, as sources from which I have derived much valuable information. It is right to mention that several of the early sheets of this work have been printed more than twelve months, which will account for the absence from them of reference to the most recent facts. 49 Upper Brook Street, August $th, 185G. CONTEXTS. Preface.............. Page in PRINCIPLES OF MEDICINE. Paragraph. Explanation of the Object of the Work.....p. 8;; 1, 2 Principles of Medicine. Synonyms. Whence deduced. Division into etiology. 3, 4 pathogeny, general therapeutics, and other subjects . . . . p. 33 Definition of Disease.........p. 33 5 Standards of comparison. Definition of health. Deviations from health; in func- tion; in structure. I) Physiology a standard of healthy function; anatomy—of structure. 7 Definitions of disease. 8 Variations in the standard of health. Examples. CHAPTER I.—ETIOLOGY—ON THE CAUSES OF DISEASE. Section I.—Nature and Division of Causes . . . . p. 34—40 0 Definition of causes of disease. Antecedent circumstances apt to be mistaken for causes. This error to be avoided by proving their occasional absence, and investigating the intimate nature of disease. Example. 10 Causes of disease intrinsic and extrinsic. Examples. 11 Causes of disease not sure in operation; except those "which are very strong. 12 They generally require predisposition. Examples. 13 Causes divided into remote and proximate. Remote divided into predisposing and exciting. 14 Co-operation of predisposing and exciting causes generally necessary. Examples. 15 Exceptions. 1C, Predisposition, generally deficiency of natural power of resistance. Examples of J 7 the operation of this resisting power. 18 Predisposition from error of function or structure. Other terms for predisposing 19 causes; why sometimes inapplicable. Division and nomenclature of causes conventional. Obscurity of causation. Section II.—Predisposing Causes of Disease . . . .p. 40—5L1 20 Classification of predisposing causes. 21. 22 I. Debilitating causes and their modes of operation. Imperfect nourishment. 23 Impure air. Excessive exertion of body or mind. Want of exercise, and 24 sedentary habits generally. Long continued heat. Long continued cold. Viii CONTENTS. Paragraph. 25—28 Habitual intemperance. Depressing passions. Excessive evacuations. 29, 30 Previous debilitating diseases. 31,32 II. Excitement, examples. III. Previous disease; operating by change of struc- 33 ture; by persistence of cause. Examples. 34, 35 IV. Present disease or defective function. Zymotic material in the body. 30,37 V. Hereditary constitution. VI. Temperaments. Definition and nature; san- :;8—41 guine; phlegmatic; bilious; nervous. Diathesis. VII. Age, and itspredis- 42—46 positions. Infancy, Childhood. Puberty. Full-growth. Adult age. Old 47—49 age; influences exemplified in vascular and nutritive functions. VIII. Sex. 50 IX. Occupation. Section III.—Exciting Causes of Disease.....P- 52—9o 51 Operation of exciting causes. Division into cognizable and non-cognizable. Classification. 52 I. Cognizable Agents. (1.) Mechanical causes: examples of their physical effects. Vital operation of severe injuries. 53 (2.) Chemical causes: extrinsic; intrinsic; modes of operation, as local irritants, as corrosives, as septics, and as chemical alteratives; examples of their effects. 54,55 (3.) Ingesta. Non-alimentary: condiments; action of salt in excess. Intoxi- 56 eating liquors, use and abuse of. Delirium tremens; principles of treatment. 57 Tea and coffee. Water. Adulterations of food, impure water, medicines, 58 Aliment, unfit in quality; a due mixture requisite. Simple principles, such as fibrin, starch, gum, &c. insufficient. Bread the staff of life. Dr. Prout's 59 views on aliments, sanctioned by familiar experience. Extent of conversion of the elements of food by digestion. Dumas' views; objections. Experi- 00, Gl ments of Petroz and Boussingault. Liebig's views. Effects of alimentary principles; albuminous, gelatinous, oleaginous, farinaceous, and saccharine. 02, 63 in defect, in excess, or bad in quality. Adaptation of food to climate, &c. Action of oil, starch, sugar, vegetable acids, &c. Aliment generally, in ex- cess. Defective. Symptoms of inanition. Chossat's experiments on star- vation. Liability of the ill-fed to zymotic diseases. 04 (4.) Violent exertion, effect on the heart, brain, lungs, and other organs. Par- 05 tial exertion. Exhaustion from fatigue. Want of exercise. 06 (5.) Mental emotion. Strong. Slow emotion. Mental anxiety. Excessive mental exertion. AYear and tear. 67 (6.) Excessive evacuation. Effects. Syncope, cerebral, and cardiac. Other effects and resulting diseases. OS (7.) Retention, Diminution, and Suppression of Evacuations, alvine, urine, bile, &c. i)9 Lower degrees common in disease. Suppression of artificial discharges; of cutaneous eruptions, &c. 70 (8.) Defective cleanliness, ventilation, and drainage. Their prevalence; modes 71 in which they excite disease. Filth, action on skin, &c. Filth in dwellings. 72 Defective ventilation often insidious in its operation. Evil results, in dwell- 73 ings and public buildings. Defective drainage; results of effluvia from cess- pools. London sewers. TJntrapped drains. Causes and consequences. 74, 75 (9.) Temperature and changes. Effects of extreme heat or cold. Cold, applied generally and locally. Dr. James Arnott's method of applying cold. Power of the body to resist cold. Burns and scalds. Shock to the system. Ex- 76 periments of Sir A. Cooper and Chossat on cold. Stimulating effects of heat. 77 Fartial application of heat. Coup de soleil. Sedative effects of cold. In- CONTENTS. IX Paragraph. tropulsion of blood. Effect on the arteries. Indirect effects of cold. Chil- 78 Mains and frostbite. AVarmth to be restored in benumbed parts, gradually. 79 Mode in which cold excites internal disease. Dr. Alison's views: objections. It acts by deranging the circulation, and chemical changes of the blood. 80 Symptoms of "cold caught." Railway draughts. Fogs. Ozone. Means of diminishing susceptibility to cold. Cold bathing. AVater cure. Good 81 and bad effects. Effects of cold proportioned to previous state of the body. Atmospheric changes. II. Non-cognizable Agents.—Zymotic poisons divided into Endemic, Epi- demic, and Infectious. 82 (I.) Endemic Poisons. Proofs of their existence. Sources. Malaria. Na- 83, 84 ture of malaria. Its properties. Localities of malaria. Its virulence in 85 proportion to heat with moisture. Diseases caused by malaria. Periodi- 86 city of their attacks, causes of this. Kinds of malaria. Endemic diseases from cognizable causes. 87, 88 (II.) Epidemic Poisons. Proofs of their existence. Epidemic. Cognizable 89, 90 causes distinguished from non-cognizable. Epidemic constitutions or pe- 91 riods. Nature of epidemic influences. Dr. Prout's observations. Ani- 92 malcule origin of epidemic diseases; Linnaeus; Sir H. Holland, &c. Ehren- berg's observations. 93,94 (HI.) Infectious Poisons. Proofs of their existence. Modes of infection: by 95,96 wounds; by contact; by aerial communication; by several modes. Diffi- 97, 98 culties of explaining infection. Analogy of fermentation; of animal and 99, 100 vegetable generation; examples. Parasitic view of infection confirmed by 101 circumstances which promote and check it. Character of cholera infec- 102 tion. Peculiarities of infectious diseases, of endemic diseases, of epidemic 103 diseases. Diseases propagated in several ways. Pestilences. General 104 operation of all these causes depressing, but may excite reaction. Effect 105 modified by the weather. Means of checking or counteracting zymotic poisons. Antiseptics. Stimulants. Tonics. Eliminants. CHAPTER II.—PATHOLOGY (PROPER)—THE NATURE AND CONSTITUTION OF DISEASE. 106 Disease composed of elements. Knowledge of these essential to medical science. Analogy with chemistry, &c. Primary elements of structure and 107 function; healthy and diseased. Primary elements of disease. Alterations 108 of these elements in degree, and in kind. Table of primary elements of 109 disease. Table of proximate elements of disease; in excess, defect, and 110 perversion. These elements are the especial objects of general patho- logy .......P- 95—97 FUNCTIONAL DISEASES—PRIMARY ELEMENTS. Section I.—Diseased Irritability . . p. 97—102 111 Irritability. The distinctive property of muscular fibre. Dependent on sup- ply of blood. Structure of muscular fibre. 112__Hi la. excess. Varieties in strength, in mobility, and in duration. Examples. 115 Causes. Remedial measures. 116—118 Defective, in force, mobility. Examples. Connexion of irritability with 119 nerves not essential. Remedial measures. 2 X CONTEXTS. Paragraph. Section II.—Diseased Tonicity . . . . p. 102—105 120 Tonicity; description; function; distinct from irritability; as proved by dif- ferent effects of heat and cold. Long recognised practically. 121, 122 Excessive. Examples; effect on pulse. Remedial measures. Sedatives. Cold. 123,124 Defective. Exr.mples: atony, retarded and dichrotous pulse. Remedial mea- sures. Tonics. 125 Elementary Nervous Functions. Dependent on supply of blood. In- fluenced by poisons; mechanical irritation; heat, &c. Expenditure of ner- vous matter . . . . . p. 106—107 Section III.—Diseased Sensibility . . p. 107—115 126 Sensibility referable to the nervous system, and divided into the centric and local. General. Excessive, from excitement, from disease, from temperament. Pa- 127,128 thological causes. Remedial measures. Narcotics. Tonics. AmesthesiH by inhalation of chloroform and ether. Mode of action. Cautions. 129, 130 Defective. Causes: from disease, nge, temperament. Remedies. 131 Perverted. Examples; causes. Remedies. 132 Local sensibility. Variations illustrated by experiment. Pathological causes. 133—136 Excessive, in orifices, in internal organs. Pain and other varieties. Re- 137,138 medial measures. Local anodynes. Benumbing cold. Defective. Para- lysis of sensation. Remedies. Section IV.—Diseased Atoluntary Motion . . p. 115__120 139 Division into general and partial. 140,141 General voluntary motion, in Excess: examples. Phrensy; Hysteria; taran- tulism, &c. Defective: examples. Lethargy; catalepsy; hysteria, &c. 142 Perverted: examples. Chorea; delirium tremens; shaking palsy, &c. 143,144 Partial, excessive. Tricks; fidgets. Defective; pathological causes: exam- 145 pies. Remedies for diseased voluntary motion. Excessive. Narcotics; calmants; douche. Modes of action of these remedies. Remedies for de- 116 fective volition. Stimulants. Mental excitement. Revulsives. Reme- 147 dies for perverted volition. Narcotics; tonics. Remedies for locally dis- eased volition. Electricity, &c. Section AT.—Diseases of Reflex and Sympathetic Neryo us 152 153 LXFLUKXCE • • p. 121-130 14«, 149 Natural reflex function : examples. Excessive, in involuntary muscles • ex 150,1*1 amples. In voluntary muscles: examples. Convulsions; centric and eccen- tric. Partial, by reflected irritation; spasms; cramp, &c. Irritation of involuntary muscles; the spinal marrow the centre of reflexion Pathological causes of inordinate excito-motion; irritation of spinal marrow or its nerves; accumulation by rest; from action of opium, &c. Epileptic fits. Action of strychnia and other poisons. Tetanus. Hydrophobia 1-1 Defective reflex motion. In coma, asphyxia, sinking, &c. Sleeplessness from exhnustion. 155 Remedial measures for excessive reflex action. Narcotics, nervous sedatives irA .„ ^ant«, chloroform, tonics. For defective. Stimulants; opium lo6, U, Reflected or sympathetic sensations. Examples. Spinal and superficial sensi bihty; involuntary reflex action; chorea. Remedies. CONTENTS. XI Section VI.—Diseased Secretion ... p. 130—140 Paragraph. 158 Secretion due to a vital property; aided by chemical affinity; not to be ascribed to nervous influence. 159—161 Changes due to altered supply of blood, or to nervous influence. Excessive. 1 '->2—164 Effects : forwards; examples: backwards; on the organ; examples. On the 105,166 blood: examples. Relations of bile and urea. Remedies. Depletion and other evacuations. Astringents. Alteratives. 167—169 Defective secretion. Causes. Effects: forwards; examples: backwards; on 170, 171 the organ; examples. Suppression of excretions; uroemia, cholajmia, &c.; 1 72, 173 extreme; moderate; in idiopathic and symptomatic fevers, gout, rheuma- 174, 175 tism, and other diseases. Remedies, through the circulation. Special 176—178 stimulants. Alteratives. Tonics. Substitutes for defective secretion. Perverted secretion. Examples. Effects. Remedies. Section VII.—Diseases of the Constituents of the Blood p. 140 179 Constituents of the blood, when altered, form elements of disease. 180, 181 Enumeration of constituents and modes of alteration. Chemical composition of the blood. Disease of Red Particles . . .p. 140—148 182—184 Natural offices, composition, and proportions. Excessive. Examples. Signs and effects. 185,186 Deficient. Examples and effects. Alterations; in colour; in shape and size; 187,188 breaking up. Arterial change; cause. Mulder's and Carpenter's notions. 189, 190 Mr. W. Jones' observations; explanation. Mr. Gulliver's observations. 191—193 Origin of red particles. Causes of their decrease. Spoilt blood. Disor- ders of spleen and uterus. Remedies for excess, defect, and alteration of red particles. Section VIII.—Fibrin and White Corpuscles . . p. 148—161 194 Nature of fibrin. Structure in washed clot, or lymph; circumstances inducing 195 fibrillation; composition; an oxy-protein. Purposes: materials of tex- tures. White corpuscles. Excess of fibrin. Examples in inflammation. Signs and effects. Increase of white globules, at expense of red. Defi- 196, 197 ciency of fibrin. Examples ; fluidity of blood, in fevers; in Gaspard's ex- 108 periments, &c. Causes. Effects: hemorrhage; congestion, venous mur- murs, &c. Magendie's experiments. 199_201 Alterations in quality: apparent from character of coagulum, which shows 202 properties of self-coagulation, contraction, and separation. Self-coagula- 203 tion; varieties and causes; its occurrence within the vessels. Contraction; 204,205 varieties and causes; cupped blood. Separation; causes, varieties. Causes 206, 207 of the buffy coat. Appearances of coagulated blood. Large clot; small 208' clot. Separated and cupped; mode of exhibiting these properties. Source 209 of fibrin, and formation of white globules. Increase by inflammation. Ma- terial of coagulable lymph. Varieties. Coagulation of fibrin during life. Vegetation and polypi. 210,211 Remedies for Excess of Fibrin. Blood-letting. Evacuants. Narcotics. Tod oil. Mr. Blake's experiments. 212 Remedies for defect; diet; regimen; stimulants; tonics; antiseptics; oxydating agents. 213—215 Means of altering quality of fibrin; depletion; alteratives; salines. Tonics; diet and regimen. Xll CONTENTS. Paragraph. _ Section IX.—Albumen and other Animal Principles Dissolved in the Serum .... • p. 161-163 216 Natural proportion and offices of albumen. 217, 218 Excess. Examples. Causes. Remedies. 219,220 Defect. Examples. Effects. Dropsical diathesis. Remedies; by checking waste; by increasing supply. Section X.—Fatty and other Combustive Matters . p. 103—166 221 Kinds of fat in the blood. Sources. Sugar in the blood. 223, 224 Excess. Examples. Milky serum. Depends on the presence of unassimi- lated chyle. Fat formed by degeneration of albumen; fatty cachsemia; re- medies. Obesity. Defect. Examples. Causes of atrophy; remedies. Section XI.—Saline and Mineral Matters . . p. 166—168 225 Thirst caused by salt. Natural, proportions; uses. Excess—scurvy? 227 Defect: in yellow fever and malignant cholera. Effect of saline injections. Use of salines in fevers. Treatment of cholera. Section XII.—AA'ater . . . . . p. 168—170 228 Natural proportion. 230 Excess. Examples and effects. From too much drink. Deficiency. Ex- 231 amples. Symptoms. Causes. Effects of cholera—of abstinence from li- quids. Remedies for excess and defect. AVater cure and dry diet. Drink- ing : use and abuse. Water increases waste of tissues. Section XIII.—Changes in the Blood by Respiration . p. 170—175 232—234 Analysis of changes. Excess. Examples in disease ? Inhalation of oxygen; effects. 235, 236 Defect: the element of asphyxia. Effect proportioned to suddenness as well 237 as degree. Explanation of this. Analysis of asphyxia. Classification of 238 symptoms. Defect gradually induced. Hybernation. Cyanosis: state of 239 the functions; little muscles and much fat; with defective respiration. 240 Emphysema. Remedies for defect; Lowering functional activity. Treat- 241,242 ment of asphyxia. Stimulants. Warm bath. Promoting respiration. 243 Other means of arterializing the blood. Treatment of congestion of apnoea. 244 Diet in dyspnoea. Section XIV.—Changes in the Blood by Secretion . 175—182 245 Defective secretion of urine. Experiments of Prevost and Dumas. Effects 246 of diseased kidneys. Views of Frerichs. Acute and chronic albuminuria. 249 Defective secretion of bile. Examples. Effects on blood, &c. Bilious 251 attacks. Perspiratory nature of secretion; checked by cold; effects. Ari- carious action of skin and kidneys. Rheumatism; increased acid in blood; materies morbi. Remedies to be directed to this element. 252 Treatment of rheumatism: by nitre; lemon juice; the author's plan. Water cure. Section XV.—Changes in the Blood from the Transformation of Chyle and of the Textures of the Body . 182__188 253 Natural changes imperfectly known. Gout and other lithic acid diseases. 254 Decay of textures. Causes: rich and too highly azotized food. Treat- ment of uraemia. Treatment of cholEemia; of bilious attack. Morbid effects of lithic acid on the kidneys. Nephralgia and nephritis. Gout in CONTENTS. Xlll Paragraph. various forms; irregular; regular; sthenic; asthenic; chronic; chalkstones of gout. 255 Diabetes. Sugar traced to the blood; formed in the liver. Sugar often pre- sent in the urine of the aged and asthmatic. 256 Treatment of gout and diabetes, compared and contrasted. Treatment of diabetes. Treatment of gout by alkaline eliminants. Cautions. Local treatment. Fit of gout. Gouty constitution. Gout in the stomach. 257 Azoturia, or excess of urea. Result of decay of texture. Remedies: repose; stimulants; tonics; narcotics; tea and coffee. 258 Fatty transformation in the blood; impairing nutrition. Fatty degeneration. Section XVI.—Tox.emia—Changed Properties of the Blood from the Presence of Foreign Noxious Matters . . 189—194 259 The blood the seat of morbid poisons; and of the virus of malignant disease; proofs. Examples of action of morbid poisons on the blood. Decomposing matter a nidus. Poisons of exanthemata; of typhoid fever, &c.; traced in operation, and with the reacting powers of the system causing the varieties of these diseases. 260 Treatment indicated by the operation of the poison, and subsequent reaction. Remedies to counteract the poisons. To destroy or expel them. To re- gulate and sustain the functions. CHAPTER III.—PROXIMATE ELEMENTS OF DISEASE. Section I.—An.emia ..... p. 195—200 261 Explanation of proximate elements of disease. 202—264 General anosmia. Nature, exciting causes, and symptoms. Physical signs. 205—267 Changes in the blood. Symptoms of excitement in anaemia. Explanation 268, 289 of these symptoms. Symptoms of coma, &c. Cases and interpretation of 270, 271 nature of anaemic coma. Nutrition in anaemia. Predominance of nervous 272 symptoms. Fatal terminations. Extraordinary success of remedies in anaemia. Iron and other tonics; modes of exhibition. Regimen and diet. Treatment of nervous symptoms. Venous murmurs. 273 Partial anosmia. Examples. Effects: cause of gangrene; numbness; wasting; degeneration. Treatment. General and Local. Section II.—Hyperemia or Excess of Blood . . p. 206 274 Definition and nature. Classification of varieties. Section III.—Plethora—General Excess of Blood p. 206—211 275—277 Origin of plethora. Subjects. Symptoms. Tendencies. Causes. Division 278,279 into Sthenic and Asthenic. Symptoms of Sthenic. Subjects. Tendencies. 281__283 Asthenic. Symptoms. Subjects. Tendencies. Results. Fever. Gout. _>84__286 Remedial measures. Bloodletting; where unfit. In sthenic, other mea- sures needed. In asthenic, tonics as well as evacuants and eliminants Diet and regimen. XIV CONTEXTS. 287, 288 289 290 291, 292 294 295, 290 Paragraph. Local Hyperemia. Excess of Blood in a part. Section IA'.—AVith Motion diminished. Congestion p. 211—229 Congestion analyzed. Its causes classed. Congestion from venous obstruction. Examples, in health and in disease. Ex- planation of congestion in emphysema. Congestion from atony of the vessels. From general debility. Hypostatic. From local debility; over-distention. Examples. From intropulsive ac- tion of cold and malaria. From over-excitement or inflammation. Exam- ples and illustrations by microscope. Stagnation in the vessels. From arrest of secretion or capillary circulation. Explained by Mr. Graham's law of "Osmotic force." From imperfect respiration. (Is the power of the heart sufficient of itself to maintain the circulation? Dr. Sharpey's experiments. Microscopic examinations; fallacies. Objections to the supposition of spontaneous movement of the blood particles. Dr. Carpen- ter's assumption of the existence of a motory power in the capillaries con- sidered, and admitted as identical with Graham's "Osmotic force.") Ob- servations of Mr. Erichsen. Obstruction to circulation in asphyxia, partly from contraction of the small arteries, but also by suspension of osmotic force in capillaries. Atony of vessels also impedes transit of blood. Ex- periments to show the neutralization of force in the flaccid vessels. Cause of long continuance of congestion. Symptoms and effects of congestion. 1. In congested part—Impaired func- tions. Effects on secretion explained. Production of flux. Examples. Considerable congestion required to produce dropsy. Amount of tension and quality of blood determine quality of effusion, liquid and solid. Ex- amples. Albuminuria referred to congestion of the kidney. Reasons. Congestion continuing causes hypertrophy of a peculiar kind. Origin of granular disease and cirrhosis. Other instances. 2. Effects of local con- gestion on the system. Fit of ague deprives it of blood. Examples. In- jury to blood. This congestion may cause cachaemia. 313 Remedies for congestion. Removal of causes, venous obstruction and causes 314, 315 of atony. Posture. Pressure. Friction. Exercise. Astringents and 316,317 tonics; when applicable. Stimulant remedies; Operations shown by the 31s microscope: when hurtful. Depletion and other evacuants. Hremostasis 319, 320 or counter congestion. Preceding remedies combined or alternated. Pre- vention of congestions by increasing tone. Section V.—Local Hyperemia. Excess of Blood in a Part with Mo- tion INCREASED. DETERMINATION OF BLOOD . . p. 229__240 321,322 Examples in health and in disease. Determination to the head. Examples, 324, 325 with symptoms. The cause of various fits. Determinations caused by 32G, 327 stimuli. Physical cause of determination of blood. Enlargement of ar- 328, 329 teries, proved by the author's microscopic experiments. Observations of 330 Mr. Paget and Mr. W. Jones. Cause of the enlargement, a loss of tonicity. 331 Influence of the nerves on the arterial tonicity. Experiments of Bernard 332 and W. Jones. Final cause of determination to supply more blood where wanted. Determination from intropulsion. Subjects of determination. Determination may cause anaemia in other parts. Determination affects any arteries. 333 Symptoms and effects of determination of blood. Parts most subject to it. 334—336 To the head. Explanation of its different effects in different cases. To 299 300- -302 303 305, 306 307 3C8 309, 310 311, 312 CONTENTS. XV P'ragraph. 3^7—340 the kidneys. To the mucous membranes. To the skin. Other symp- 341 toms. Determination if continued leads to hypertrophy. o42, 343 Remedies. Removal of causes. Means which promote the tonic contrac- 311, 345 tion of dilated arteries. Cold. Astringents. Sedatives which restore 346 contraction of vessels. Derivants. Posture. Evacuants. Blood-letting; 347,318 general and local; its effect seen by the microscope. Cases requiring 349 blood-letting. Remedies to relax the arterial system and quiet the heart. Measures to equalize and strengthen the circulation. Tonics. Section VI.—Results of Hyperemia .... p. 240—266 350 Hemorrhage, flux, and dropsy, results short of inflammation. 351 Hemorrhage from plethora. Examples. Epistaxis, haematemesis, &c.; 352 from congestion of venous obstruction. Examples. Pulmonary, bronchial, 353 gastric, &c. From atony of vessels; from posture; from intropulsion of 354,355 cold. Examples. From determination of blood. Examples. Epistaxis; 35C apoplexy; hsematemesis. Additional element of hemorrhage in the vessels 357, 358 or in the blood. Blood-vessels diseased. Examples. Blood diseased. 359 Hemorrhagic diathesis. Mode in which blood is effused. By rupture or through the pores? 360, 361 Varieties of hemorrhage. Sthenic and asthenic defined. Symptoms. Mo- 362 limen hemorrhagicum; jerking pulse, how produced. Faintuess; Reaction. 363, 364 Transition to inflammation. Examples. Local effects and symptoms. 365 Passive hemorrhage. 366, 307 Treatment of hemorrhage. Remedies for hyperacmia. Styptics. Cases re- 368,369 quiring a speedy check. Active or sthenic. Passive or asthenic. Me- 370 chanical means. Special styptics. Internal remedies. Tonics, purgatives. and styptics. Action of styptics considered. 373—375 Flux and Dropsy. From plethora. Examples. From congestion. Ex- periment of Lower. Examples in disease. 37G—37s From weakness of the vessels. After excitement. Intropulsion of cold. 37.') From determination of Mood. Examples; active flux; active dropsy. From stimulants. 360—382 Flux and dropsy vicarious. Examples. Circumstances causing hyperemia 3S3 to end in these results: in the vessels: in the blood. Combination of these 3-4 circumstances in anaemia. Diseased blood from defective excretion, espe- cially by the kidneys. Examples and proofs. Cause of anasarca after 3Sr, scarlatina. Changes in the kidneys. Dropsy and flux with albuminuria: 3S6 why inflammatory: resemblance to rheumatism. Thinness of blood, cause 3^7 0f asthenic dropsy. Dropsy from retention of water and excrementitious 3S3 matter in the blood. Malnutrition. Proofs. Distinctive pathology of 38.") fluxes and dropsy. Causes of each. 390 General treatment of flux and dropsy. Remedies for hyperaemia. Remedies 391 for malexcretion and malnutrition. 392,393 Treatment of fluxes. Removal of causes. Derivants. For sthenic flux; 39l' evacuants and depletion: not to be hastily checked. For asthenic flux; astringents and tonics. Dry and tonic regimen. 395 Treatment of dropsy. Means to remove effusion and restore action of kid- 396, 397 neys in sthenic dropsy. Means to improve the blood in asthenic. Re- 39s' currence of dropsy requires variation of remedies. Circumstances which indicate tapping or puncture. Cautions. Means to prevent recurrence of dropsy. Pressure. Injection of iodine. xvi CONTENTS. Section VII.—Local Hyperemia. Excess of Blood in a part, with Motion partly increased, partly diminished—Inflammation p. 266—352 Paragraph. 399, 400 Inflammation not understood from its elements not being studied. Defini- tion according to its nature; according to its signs. 401 Causes of Inflammation and their Mode of Operation. Predisposing; weakness, or excitement. Exciting causes divided into local and general; 402 direct and indirect. Local irritants; mechanical, chemical, and vital. 403 Examples. Poisons and other irritants in the blood. Predisposition to 404 catarrhs. Indirect causes produce congestion. Causes mixed in opera- ■105, 406 tion. Checked hemorrhage and flux. Irritants operate primarily on the 407 nerves. But inflammation is excited without nervous irritation, and when 408 nerves are divided. Cause essentially acts on vessels, producing some- times determination first, sometimes congestion. 409 Phenomena and Nature of Inflammation. Difference from congestion; 410 from determination. Essential characters established; increase of blood, 411 with motion increased and diminished. Cause of the obstruction. Views 412 of Cullen, AV. Phillip, Hunter, Kaltenbrunner, and Alison, considered. 413 Existence of congestion and determination proved. Atony of the vessels 414 one cause of obstruction. Examples and experiments. Another cause of 415 the blood: adhesion of white globules; their increase. Description and 416 production of white globules; Mr. Addison's observations; Mr. Gulliver's. Appearance of frog's web after irritation. Adhesive property of white glo- 417 bules; those recently formed have no cell-wall. The presence and proper- 418 ties of white globules essential to inflammation. # Variation in the osmotic force of the capillaries. Share which the red corpuscles take in the ob- struction, questioned by Dr. Hughes Bennet, and Mr. Paget: affirmed by 419,420 Mr. Gulliver. Conclusions as to the process of inflammation; essentially 421 complex. Effect of obstruction to expend force on the arterial capillaries, and to modify the osmotic force and composition of the blood. This oppo- sition of obstruction to force the cause, both of construction and of destruc- tion of blood and tissue material. 422 Effects of inflammation on vital properties; on secretions. 423 Effusions; liquid; solid; general character; microscopic character. Exuda- 424 tion corpuscles. Elementary solids of inflammatory effusions. Molecules. 425, 426 Granules. Fibrils. Exudation corpuscles. Pus globules. Irregular pro- ducts. Tubercle. Mode of formation of some of these. Variety in their 427 plasticity and organizability. Other effects of inflammation. Softening. Suppuration. Slough. Gangrene. Induration. 428 Symptoms and Effects of Inflammation. Divided into local and general. 429,430 Local symptoms. Redness; causes; varieties; changes; explained and ap- 431,432 plied. Heat; cause; indications. Swelling: causes; varieties from tex- 433, 434 ture; position, &c. Pain; causes. Degrees and varieties and their causes. 435, 436 Other sensations. Effects of inflammation on contractility. On other functions and symptoms. 437 Constitutional symptoms. Inflammatory fever. Change in the blood. 438, 439 Cause of the increase of the fibrin and its contractile property. This not the sole cause of inflammatory fever. Pathology of inflammatory fever. 440,441 Causes. Reaction, irritation, altered condition of the blood. Why some 442 functions are excited and others impaired. Symptoms of inflammatory 443 fever. Its varieties: high, low. Type of fever from cause or seat of in- CONTENTS. XV11 Paragraph. 444 flammation. Explanation of this. Remittent and intermittent fever. Apyrexia. Injury to blood in continued inflammation. Nature and Symptoms of the Results or Terminations of Inflammation. 445,446 Division. The results seldom occur singly. Resolution. Its nature. 447,448 Modes of occurrence. Local symptoms. Constitutional symptoms of reso- lution. Critical discharges. Lateritious sediments in urine; cause; nature; reason of absence; reappearance of chlorides. 449 Effusion (including adhesion.) Not always a termination. History of ef- 450 fusions in serous membranes. Coagulable lymph. Varieties. Euplastic. 451 Mode of organization. Formation of vessels. Views of Kiernan, Travers, 452,453 Vogel, Liston. Cacoplastic lymph; corpuscular; (Paget) croupous (Ro- 454,455 kitansky.) Varieties and effects. Aplastic lymph. Causes of these low 456 products. Effusions of mucous membranes. Interstitial deposit. Changes 457,458 of mucus; purulent and fibrinous; stricture. Effusion in shin; varieties of cutaneous inflammation exemplified in skin diseases. Effusion in cellu- 459 lar texture. In parenchymata. Symptoms of effusion. 460 Suppuration and tclceration. Nature of pus. Microscopical characters. Distinction between exudation corpuscles and pus. Alteration by acetic 461 acid; by distilled water. Its want of cohesion. Explanation of this. 462 Liquefaction of tissues in suppuration. Chemical changes. Causes of suppuration. Circumstances tending to the conversion of the deutoxide of protein into the tritoxide. 1. Intensity and continuance of inflammation. 2. Access of air. 3. State of the blood; suppurative diathesis. Examples. 463 Mode in which they act. Observations of Mr. Paget. Pus in the blood. Process of suppuration explained; death of tissue by pressure; liquefaction and absorption of all but pus globules. Varieties of suppuration. Dif- 464 fused; Abscess: pyogenic membrane: pointing. Opening and healing of 465,465 abscesses. Granulations. Ulceration. Varieties. Causes. Softening 467 of textures. Suppuration a work of destruction, therefore depressing. 463,469 Symptoms of suppuration. Local: constitutional: varieties caused by limi- 470 tation, or not, of suppuration. Purulent deposits. Nature and causes. No true absorption of pus. Pus frequently in the blood in severe inflam- mation. Cachaemia usually precedes pyaemia. Depression from suppura- 171 tion. Cause of rigors. Hectic fever. Varieties of pus; laudable; ill-con- ditioned. 473,474 Gangrene. Process of sloughing; gangrene; and sphacelus. Causes of 475 gangrene; interrupted circulation; noxious agents. Local symptoms and 476 effects of gangrene. Varieties. Constitutional symptoms. Combinations and gradations of the results of inflammation. ArARiETiES of Inflammation. 177, 478 Sthenic and asthenic; symptoms and results. Acute inflammation generally 479 sthenic; symptoms, duration, products. Subacute. Chronic; generally asthenic; symptoms, duration, results. Cause of their variety. 480 Congestive inflammation ; nature, symptoms, results. 4S1 Phlegmonous inflammation; nature; causes; type and symptoms. 4S2 Erythematic and erysipelatous; local symptoms and effects; fever; cause ,{83 specific. Pyaemia. Pellicular; asthenic; symptoms; low fever. Plas- tic inflammation of mucous membranes. Aphthae of adults often attended 1S1 by the growth of a confervoid vegetable. Aphthae of children. Hemor- rhagic inflammation; causes. XV111 CONTENTS. Paragrapli. 485 Scrofulous inflammation; asthenic: peculiar symptoms. Microscopic cha- racters of scrofulous matter. Changes which it undergoes. Scrofulous abscesses. Scrofulous diathesis; its external marks; symptoms and causes. Course and results of inflammation in scrofulous subjects in various tex- 186 tures. Condition of the blood. Gouty and rheumatic inflammations. Na- ture and causes. Gonorrheal inflammation; seat and effects. Syphilitic 187 inflammation; seat and effects. irv's Treatment of inflammation, best understood from knowledge of its ele- ments and of their counteracting measures. 4S9 Tabular view of constituents of inflammation. 490 Tabular view of the chief elements of inflammatory disease, and their reme- 491 dies. Comments on these principles of treatment. Remedies for incipient 492 inflammation: 1. for congestion ; 2, and 3. for irritation of nerves and ves- '493 sels. Remedies for established local inflammation; 4. for determination 494 to the part; 5 and 6. for obstruction in the part from atonic enlargement of the capillaries, and by adhesion of the white particles with accumulation 495 and impaction of the red ones; 7. Distention of vessels; 8. for effusions 496, 497 from the vessels; 9. for increased absorption ; 10. for impeded circulation ■198, 499 in the part; 11. for increased circulation around the obstructed part. 500 Treatment of inflammation with fever. Local remedies secondary. Chief 501 remedies, general bloodletting; effect. Tolerance of bloodletting; cause. 502,503 Dr. M. Hall's scale of tolerance. Objects and mode of bloodletting; in recent inflammation; in confirmed inflammation; in inflammation with plethora; in anaemic subjects; substitutes. Local bloodletting; uses. Re- cent disuse of bloodletting. Evacuants; purgatives ; combinations. Tar- 505,500 larized antimony; modes of administration; modes of operation. Mercury. 507 Calomel and opium; modes of exhibition; modes of operation. Refri^e- 508,509 rants. Salines. Sedatives. Diuretics. Counter-irritation. Antiphlo- 510,511 gistic regimen and diet. 16. Exhaustion. 17. Depression from poison. 51"^ Remedies: their mode of. action Stimulants, antiseptics, tonics, &c. IS. Treatment for products of inflammation, liquid and solid; iodine; nitric acid; cod liver oil. Treatment of Varieties of Inflammation. 513-516 Sthenic. Asthenic. Acute. Subacute. Chronic. Congestive. Phlegmo- 517—519 nous. Erysipelatous. Pellicular. Hemorrhagic. Scrofulous. Treat- 520,521 ment of the scrofulous diathesis and deposits. Cod liver oil. Rheumatic and gouty. Gonorrhoea! and syphilitic. CHAPTER IV.—STRUCTURAL DISEASES; OR DISEASES OF NUTRITION. Section I.—Nature and Classification . . . , p. 353__317 522 Arrangement of structural diseases. Table of elements. Structural disease 523 often complicated. Objects and mode of natural nutrition. Blood forma- •ri21 tion. Materials of nutrition, derived from the blood; changes in which cause variations in nutrition. Relation of nutrition to nervous influence. CONTENTS. XIX Section II.—Increased Nutrition—Hypertrophy . . p. 357—359 Paragraph. 525—527 Affects textures, or organs. Simple hypertrophy; of muscles; examples, of 5-8 filamentous interstitial tissue; of epidermis; varieties in skin diseases. Complex hypertrophy; uterus; breasts; brain; follicles; bursae, &c; liver 52^ and spleen. Treatment of hypertrophy. That of the heart curable. Section III.—Diminished Nutrition—Atrophy . . . p. 360—363 530 General emaciation. Causes : divided into those which promote decay and those which prevent nutrition, examples of each. Cause of emaciation in 53L fevers. Views of Dr. Hodgkin; Rokitansky. Drains from the body. 532 Series of causes which prevent reparatory nutrition. AVhen traced to its 533 cause, general atrophy an important sign. Partial atrophy from defective supply of blood. Examples. Treatment of general atrophy; according 534 to its cause; nutrients and aids to nutrition. Treatment of partial atrophy. Perverted Nutrition. 535 Alterations of texture in hind. Section IV.—Induration and Softening . . . p. 363—3G6 536 Both may result from inflammation, or occur independently. Nature of indu- 537 ration. Often accompanied by transformation of tissues or interstitial de- posit. Examples. 538 Softening. Specific causes. Common causes. Partial softening; nature. 539 From obstruction of vessels. Examples. From antiphlogistic treatment. 540, 541 Treatment of induration and softening, opposite but parallel. Treatment of softening generally tonic and supporting. Action of nitric acid, and other oxydizing agents. Specific causes. Treatment of mollities ossium. Section V.—Transformation and Degeneration of Textures . . . . . . . p. 3G7—375 542 Transformations generally degenerations. Exceptions: skin and mucous 543 membrane. Transformation of muscle. Four kinds of progressive dege- neration : Fibrous, granular, fatty, and osseous, or calcareous. Fibrous, re- sembles fibrous tissue but apt to degenerate further. Muscles and paren- chymatous organs exhibit this change, sometimes owing to interstitial de- 514 posit. Granular, a cacoplastic interstitial deposit or transformation; in- vades morbid as well as natural fibrous tissues, and may degenerate farther. 5 15 Fatty degeneration ; fat formed in the proper tissue of the parts, muscular, fibrous, and cellular; observations of Gulliver, Quain, Paget and Canton. Fatty liver; appearance; subjects; cause. General fatty degeneration: subjects of it. Dr. George Johnson's views of Bright's kidney. Other examples of fatty transformation. Observations of Mr. Gulliver and Dr. Davy. A chemical process like the formation of adipocire proved by Dr. Quain's experiments. Circumstances disposing to the general disorder; as affecting particular organs; often preceded by a cacoplastic deposit; always indicates a degradation of material. Analogy to vegetable matter. Effects. Examples. Calcareous degeneration; tissues most liable to it; a chemical process or pe- trifaction; manner in which this occurs ; produced spontaneously in old a^e, or as a result of inflammation. Effects. Treatment of degenerations. Means of sustaining vital powers. Hygienic measures. Tonics. Altera- tives. Mineral waters. Removal of local disorders. Treatment of fibrous and granular degeneration; of fatty; of calcareous. 516 547 XX CONTENTS. Section VI.—Deposits in or upon Textures . . ?• 376 Paragraph. 548 Definition of deposits. Nature. Division into euplastic, cacoplastic, and aplastic. 549 Euplastic deposits. Cicatrices. Reparation effected by four modes : imme- diate union of Dr. Macartney; union by first intention; by new tissue; by suppurative granulations. Drs. Macartney and Carpenter's account of the organization of cicatrices. Observations of Paget. Reparation by lymph; 551 by suppurative granulations. Modelling process of Macartney. Repara- tion by blood. Vascularity of clots. Remedial measures to promote healing of wounds, &c. 553 Cacoplastic and aplastic deposits. Examples of the former: structure; 554 causes, general and local. Cirrhosis. Granular degeneration. Structure. 555 Semi-transparent, gray, and tough tubercle: a degraded kind of lymph. 556 Observations of Gulliver, Addison, Rokitansky, Mandl, &c. Connexion with other cacoplastic deposits. Tendency of cacoplastic deposits to con- traction. Farther history shown by examples; effects; intimate nature; 557 reason of granular forms. Degeneration into aplastic, the common ten- dency of tubercle, analogous to fibrous and granular and fatty degeneration. 558 Form of tubercle. Causes. Microscopical and chemical character of gra- nular tubercle. Opaque change indicates aplastic degeneration; causes of 559 this change. Primary aplastic deposits; proof of degraded nutrition; yel- low tubercle, maturation and softening : the converse of contraction. In- 560 crease of fat in softened tubercle, and its analogy to fatty degeneration in general. Softening of tubercle attended by the formation of a material offen- sive to the system. Changes of tubercle from adjoining textures. Quies- cence of tubercle; spontaneous changes, withering; blackening; induration; 561 plastery and petrifactive change, absorption of tuberculous matter. Causes 562 of cacoplastic and aplastic deposits; congestion; chronic and asthenic in- flammation; degraded plasma of the blood with defect of red particles. 563 Seat of tubercles. Reasons of the liability of the lungs considered. Re- 564 lation of tubercles to venosity of blood. External or exciting causes of tu- bercles ; operation explained. 565 Treatment of cacoplastic and aplastic deposits. Elements to be considered. 1. Disordered condition of the blood and its causes. Cachaemia great where deposits general. Remedial measures. Supply of better materials of blood, and removal of those depraved. 506 2. Disordered distribution of blood and its causes. Various kinds of hype- raemia. Remedial and preventive measures. 567 3. Deposits already present; their effects and changes. Medicine of little power; why? Mercury; alkalies; iodine and iodides ; tonics; iron. Sol- 5G^ vents? caustic alkalies, acetic acid, naphtha, fixed oils. Cod liver oil. Theory of its beneficial operation, not from its iodine, &c, but as an oil. Confirmation of its efficacy; doubles the duration of life in phthisis. Best kind of oil, the freshest and sweetest; results of its use in nearly 9000 cases. Objection to the brown oils. Best mode of preparing the oil, and cautions. Objection to external use. Directions in the use of the oil. 1, selection; 2, mode of exhibition; 3, time of exhibition; diet, &c. Im- portance of other hygienic means. Improvement of the circulation. Means which promote absorption and oxidation. CONTENTS. XXI Paragraph. Section VII.—Morbid Growths .... p. 403 569 Definition. Names and divisions. Analogous and heterologous, &c. Section VIII.—Non-malignant Growths ... p. 404—410 570, 571 Definition. Serous cysts. Distinguished from enlarged natural sacs. En- 572 cysted tumours. Hygroma. Haematoma. Steatoma. Atheroma. For- 573 mation of these. Contents. Complex cystiform tumours. Sarcoma. Fibrous. Adipose. Chondroma. Erectile tumour. Dr. Hodgkin's view 574 of the cystiform origin of tumours. Pathological cause of morbid growths: 575 altered vital property of constituent cells; where most altered most in- 576 jurious. Hydatids. Proofs of separate vitality; nature and origin; re- production; Mr. Owen's description. Offsets of natural tissues. Situa- tions. Death; aplastic and fatty deposits around them. Echinococcus. 577, 578 Cysticercus. Distoma. Medical treatment of morbid growths, and their effects. Extirpation of cysts by iodine. Section IX.—Malignant Growths .... p. 410—420 579 Definition. Characters of malignancy; varies in degree. 580 Cancer or Carcinoma the generic term. Enumeration of species. Varieties 581 traced to different degrees of activity of cancerous matter. Some acute, 582 some chronic. Elementary structures of cancer: cells, forming fibres, &c. Varieties. Disposition to grow at expense of nutrition of the body. Pa- rasitic nature ? germs or ova. Experiments of Langenbeck. Local origin of cancer as a modification of nutrition. Dr. Hodgkin's view. Practical 5S3 deductions from pathology of cancer. Mode of origin. Cancer contrasted with tubercle. Microscopic diagnosis of cancers; often uncertain, yet mi- croscopic characters instructive. Varieties of cancer explained by differ- ence in quantity and fertility of germs; and activity of nutrition in adjoin- ing textures. Scirrhus is the chronic form. Symptoms; tendencies. Open cancer: destructive effects on part, and wasting influence on whole 5j;4 frame. Epithelial cancer; peculiarities. Pancreatic, mammary, larda- ceous, and solanoid, intermediate forms of cancer. Mode of growth. En- 585 cephaloid cancer the acute variety; in parts and subjects where nutrition 586 is active. Cause of rapid growth of encephaloid disease. Colloid cancer, the cancerous element in a separate form. Other varieties from form, &c. 587 Melanosis, black cancer. Varieties. Peculiar black matter, its nature. Pigment cells. Altered blood corpuscles. May occur apart from ma- lignant disease. Mr. Paget's remarks. Bronzing of skin. 588 Treatment of malignant growths. Indications. 1. To extirpate them; 2. 589,590 To retard their development; 3. To counteract their effects. Means of attempting the fulfilment of these. Section X.—Disorders of Mechanism . . • . p. 421 591 Changes in mechanism, elements of disease. Examples. 592-594 Dilatation; Contraction. Rupture and laceration. Displacement and com- pression. Contortion. CONTENTS. CHAPTER V.—CLASSIFICATION, SYMPTOMS, AND DISTINCTION OF DISEASES. Section I.—Nosology . . . . • P- 422—124 Paragraph. 596 Definition of special diseases. Methods of classification. 597 Symptomatic. Methods of Sauvage, Cullen, &c. Correct pathology the 598,599 true foundation of natural classification. Method of Pinel. Classification of diseases with reference to pathology. Examples of pathological classi- 600 fications. Why preferable. Pathological definitions of disease. Section II.—Semeiology and Diagnosis . . . p. 425—435 601, 602 Definition of symptoms and signs. Physical signs. Examples. Those of disease known by comparison with healthy standards. Standard of sym- metry. Anatomical standard. Physical signs explained by physical laws. Vital symptoms. Called also functional and physiological, general and rational. Examples. Sources of symptoms. Pulse. Skin. Tongue. Stools. Urine. Knowledge of pathology the best key to symptoms. Sta- tistics an imperfect and temporary substitute. Respective value of phy- sical signs and vital symptoms; examples. Division and nomenclature of symptoms. Diagnosis defined. How founded. Division into general and special. Dia- gnosis, illustrated by problems, and modes of solution. Need of every branch of medicine in diagnosis. The test of ability and knowledge. Ob- jects of examination with regard to diagnosis, prognosis, and practice. 603, 604 605, 606 607 i'iOH, 609 610 611, 612 613, 614 615 CHAPTER VI.—PROGNOSIS. FOREKNOAVLEDGE OF RESULTS OF DISEASE . . . p. 436—152 616 Definition. Prognosis, empirical or rational: Empirical that of infant me- 617 dicine. Prognostics of Hippocrates. Good and bad signs. Rational pro- s's gnosis described and exemplified. Circumstances from which prognosis 619 maybe formed, 1. relating to the subject; 2. to the disease; 1. Age of the subject; sex; temperament: previous diseases; present diseases; previous habits; condition of the patient at the time of the attack. 620 2. Of the disease. The cause, situation and nature, extent and progress; the 621,622 character of the symptoms. Good symptoms. Bad symptoms, signs of impediment to a vital function, and approach of one of the modes of death. Operation of all the modes of death on the blood, proved. Modes of death arranged in table. 625 Death by Syncope. By spasm of the heart. Causes: examples. By loss of irritability: causes; poisons; diseases; symptoms of approach. 62o Death by Asthenia. Gradual failure of the circulation. From diseases- symptoms of approach. 627 Death by Asphyxia. Distinction. Symptoms. Causes. Varieties in re- lation to prognosis. 0-23 Death by Coma. Causes: symptoms. Combined with excitement of the medulla. How does coma cause death? By abolishing supplementary voluntary breathing. Stertor. -Medullary symptoms the most serious and induced where coma is profound. CONTENTS. XX111 Paragraph. 629—631 Death by Paralysis. Injuries to the medulla, to the afferent nerves of re- spiration, to the efferent nerves. Examples. Paralysis of spinal nerves 632 with and without injury to the cord. With injury of cord itself, symp- toms and fatal tendencies. 633 Death by Necrcemia. Explanation. Proofs of death of the blood. Mode 634 of spreading death to other parts. External causes of necroemia. Vital resistance to its causes. Symptoms. 635 Modes of elimination of causes of necrtemia. Intrinsic causes of necraemia. 636—638 Symptoms of death by necraemia. Slow deaths, more general. CHAPTER VII.—PROPHYLAXIS AND HYGIENICS, p. 4-33—186 639 Definitions. Prophylaxis connected with special pathology. Hygienics refer G40 to means of resisting disease generally, and to means which maintain the general health. Subjects for consideration enumerated. 641, 642 Food. Purposes of; essentials of wholesome food. AVheaten bread; unfer- mented bread. Meat: use and abuse of cooking. A7arieties of meat, their constituents and wholesomeness. Fish, poultry, &c.; broths and soups; G13 eggs and milk; cheese. Vegetables. Choice of food and hours of meals. 644 Breakfast and luncheon, dinner, tea, supper. Adaptation of meals to habits. Regularity in the hours of meals. Injury from long fasting. 645 Clothing. Purposes. Provisions for alteration in the covering of the lower 616 animus; according to season, weather, and temperature. Materials of 647 dress. Objects in selecting them. To protect from cold; from currents 648 of air; from dampness and dryness. Cautions in changing winter for suni- 649, 650 mer clothing. Summer clothing. Silk vestments, electric influence. 65l' Cases requiring additional warm clothing. Coverings for the head. Va- rious cautions. 652 Air and temperature. Beneficial effects of pure air; of change of air, seaside 653 and inland. Travelling: high winds. Dry air; its ill effects; modes of preventing them; causes; soil; winds. East-wind. Ozone. The sirocco; 654 effects. Damp air. Effects. Mode of operation. Cold and damp air; morbid effects. Causes of damp air; winds, soil, dwellings. Marine hu- midity. Protective and counteractive means. Temperature; average most healthy. Causes of the oppressiveness of heated rooms. Salutary influence of cool air. Cases requiring additional warmth. Mr. Jeffery's respirator. Ventilation. Modes of ventilating in winter and summer. Dr. Arnott s 658, 659 principles and contrivances. Haden's plan of ventilating the Brompton Hospital. Supply of warm air. Forces used in ventilation. Means and agents for purifying air. 660, 661 Bodily exercise. Beneficial effects of moderate exerc.se. Direction, and 662 cautions regarding exercise, according to age, strength, occupation, &c. Times for taking exercise. 663 664 Caution as to amount and kinds of exercise, and their effects considered Cr,t Mental occupation. Moderate and equal exercise of mental faculties bene- 66 667 ficial. Adaptation to age; in infancy; mental education and discphne; 6,15 656 657 in youth; in maturity. Body and mind to be equally exercised; evil re- sults of neglecting, and good effects of observing, this rule. Variation of 669 occupation invigorates the mind. XXIV CONTENTS. Paragraph. 670 Sleep. Effects and nature of healthy sleep. Symptoms: gaping anu yawn- 671, 672 ing. Circumstances which promote sleep: those which prevent or disturb 67'-; it; nightmare. Evil consequences of want of sleep. Directions to bad sleepers. Means of inducing sleep: Mr. Gardner's; the author's; Dr. 67-1 Franklin's, &c. Reasons of their failure. Amount of sleep proper; varies 675 with age, sex, strength, occupation, &c. Sleep to be limited, especially in certain cases. 676 Excretion. A proper subject for hygienic rules; depends on due activity of 677 many functions. Intestinal excretion. Importance of punctuality and 678 time for its evacuation. Various aids; in diet, exercise; by habitual ape- 679 rients; their safety and efficacy when needed. 6SO "Urinary Excretion; its importance. Amount and quality varies with diet, exercise, &c. Cold water and other diuretic drinks. Propriety of timely 681 but not too frequent evacuation. Excretions of the shin not fully known; 682 objects specified, promoted by various hygienic means, and specially by bathing, washing, and friction: operation and useful application of these. Vapour and shampooing bath. PRINCIPLES OF MEDICINE. EXPLANATION OF THE OBJECT OF THE WORK. 1. The Principles, Elements, or Institutes of Medicine con- sist of those leading and general facts and doctrines regarding disease and its treatment, which are applicable, not to individual cases only, but to groups or classes of diseases. The same branch of medical knowledge is also designated by the term General Pathology and Therapeutics, to distinguish it from Special Pathology and Thera- peutics, or the theory and practice of medicine in relation to individual diseases. 2. The principles of medicine may be deduced in part from a know- ledge of the animal structure and its functions (anatomy and physio- logy,) conjoined with an acquaintance witli the agents which cause and remove disease; they are chiefly arrived at by a generalization of the facts observed in an extensive study of disease itself, whether these be eifects manifested in the living or in the dead body. But so far as they have been ascertained, they become more intelligible to the stu- dent if explained synthetically, that is, by describing first the causes of disease, then the operation of these on the body, and lastly, the re- sulting changes in function or structure which constitute the more ele- mentary forms of disease. 3. Etiology, or a knowledge of the causes of disease, appro- priately introduces the consideration of the effect—disease itself; the nature and constitution of which may then be conveniently considered under the head of pathogeny, or pathology proper. This last sub- ject is the one to which I design to chiefly direct attention, and there- fore, it will occupy the greater part of the work; but it Avill be also combined with such an elementary view of the principles of treatment (general therapeutics,) as reason and experience may supply. 4. A short general view will afterwards be given of the phenomena of disease (semeiology,)—of the division and classification of diseases (nosology,)—of their detection and distinction from each other (diag- nosis,)—of the indications of their probable results (prognosis,)—and of their prevention (prophylaxis and hygienics.) 3 31 definition of disease. definition of disease. 5. The reader is presumed to be acquainted with anatomy and phy- siology: without such knowledge not even a definition of disease can be formed. Disease is known only by comparing it with the standard of health, which it is the object of anatomy and physiology to describe. Health consists in a natural and proper condition and proportion in the functions and structures of the several parts of which the body is composed. From physiology we learn that there are certain relations of these functions and structures to each other, and to external agents, which are most conducive to their Avell-being and permanency; these constitute the condition of health. But this knowledge implies that function and structure may be in states not conducive to permanency and well-being: states Avhich are deviations from the due balance be- tween the several properties or parts of the animal frame; these states constitute disease. For example, physiology, as well as experience, teaches us, that in health the digestion of food is easily performed and attended by sensations of 'comfort. But when, after food is taken, there is pain, uneasiness, sickness, eructation, flatulence, or the like, we know that the function of digestion is changed from the healthy standard—is diseased; and if this diseased function continue long in spite of the employment of remedies which usually serve to correct it, and if on examining the abdomen we find at or near the epigastrium a hard tumour, which anatomy teaches us is not there in health, we know that there is also diseased structure. 6. We find, then (§ 5,) that in this case there is disease of function, known by its deviation from a standard furnished by physiology; and also disease of structure, which is recognised by departure from a stan- dard supplied by anatomy, (§ 5.) These different kinds of disease may be, and very commonly are, combined: there is seldom structural dis- ease without some disorder of function; and in many instances func- tional disease is, or ultimately will be, accompanied by change of structure. 7. Looking, then, to anatomy and physiology as expressing the standard of health, we may define disease to be, a changed condition or proportion of function or structure in one or more parts of the body. 8. The standard of health is not, however, the same in all indivi- duals: that which is health to one may be disease to another. Thus to instance individual functions:—The healthy pulse in adults ave- rages from 70 to 80; yet there are some in whom 90 or 100 is a healthy pulse. Some persons fatten on a quantity of food on which others would starve. Muscular strength and activity, nervous sensibility and the sensorial powers, vary exceedingly in different individuals, yet all within the limits of health: Avhat is health in one would be deci- dedly morbid in another. Unusual proportions of the different struc- tures or functions to each other constitute Ararieties of temperament • and although these can scarcely be called morbid, yet they certainly give, as we shall afterwards see, a proclivity to disease. Thus pre- STANDARD OF HEALTH VARIABLE. 35 dominance of sensibility and excitability, of the excito-motory nerves over other vital functions, constitutes the nervous temperament, which is compatible with perfect health, although it predisposes the individual to diseases of a nervous kind. A preponderance of the nutritive func- tions renders a person florid and bulky, although in perfect health; but this carries with it a risk of exceeding the bounds of health, and of inducing plethora and obesity, to such an extent as to interfere Avith the well-being and order of the bodily functions, and so to constitute disease. i CHAPTER I. ETIOLOGY—THE CAUSES OF DISEASE. SECTION I. NATURE AND DIVISION OF CAUSES. 9. Causes of disease are such circumstances as essentially precede it, and to whose operation its occurrence is due. In many instances these circumstances elude our observation. In many others, the true cause, if apparent, is combined with other circumstances which have no share in producing the result, disease, and which yet are thence liable to be mistaken for causes. These circumstances are to be sifted, and the true cause discovered, only by the attentive observation of large numbers of cases, in which disease is produced. The non-essen- tial circumstances -will then be found to be sometimes absent, and that which is always present may consequently be fairly regarded as the influential cause. But this, as before stated, sometimes eludes obser- vation; in this case, as well as in elucidating the operation of circum- stances supposed to act as causes, the most useful knowledge may be obtained by investigating the ultimate nature of the disease itself, which will often throw light on its own source. Thus it was at one time a matter of doubt whether the itch could be engendered from filth, as well as from contagion; but since microscopic investigation has dis- covered the existence of the itch-mite, no doubt remains that this in- sect is the only essential cause of the disease, however its operation may be promoted by filthy habits. 10. The causes, or circumstances, inducing disease, may be intrinsic, or existing within the body, independently of any obvious external in- fluence ; or they may be extrinsic, having their origin without the body. As examples of intrinsic causes may be mentioned excess or defect of some function (such as irritability,) or of some constituent of the body (such as the blood.) Extrinsic causes are very numerous; they com- prise indeed all the external agencies which can operate on the body or mind, such as temperature, air, moisture, food, poisons, mechanical and chemical influences, and sensual impressions. 11. A great variety of agents and circumstances may thus act on the body so as to produce disease; but in most instances it seems as if there were not that uniform and constant relation between these causes and the diseases that result, which we might expect from the analogy UNCERTAINTY OF OPERATION. 37 of the operation of causation in the simpler sciences. In chemistry or in mechanics obvious effects certainly and uniformly follow obvious causes; in physiology or pathology, no doubt, certain fixed effects also follow certain determinate causes; but whether these effects become manifest as disease or not, depends on many circumstances, of which often we can take no cognizance. When the causes are of the same nature as those Avhich are operative in physics or chemistry, the ex- pected effects never fail to ensue. Thus, a cutting instrument, a red- hot iron, or a corrosive liquid, invariably produces disease, when ap- plied, because its physical or chemical operation is so energetic that it overcomes all vital properties. Certain poisons and other analo- gous potent agents, which act on, without destroying, the vital pro- perties of living parts, also, if of sufficient strength, pretty constantly produce morbid effects. Thus, opium taken internally causes somno- lency; tartar emetic excites nausea and vomiting; cantharides applied to the surface induce inflammation, &c. 12. But the most common causes of disease are seldom of this de- cided and positiAre character; they are often present without disease en- suing; and they are known to be causes only because disease is ob- served to ensue in a greater number of cases Avhen they are present, than when they are absent. Thus, improper food is a cause of indiges- tion, and exposure to cold is a cause of catarrh; yet many persons eat unwholesome food without suffering from indigestion, and many are exposed to cold without " taking cold." But those, who do suffer from indigestion, observe that they do so more certainly after taking impro- per food; and those who are affected with catarrh can often trace it to exposure to cold. The reason for this uncertainty of action is chiefly found in the difference of power which the body exerts in resisting the morbific influence; this power varies much under different circum- stances. Its failure, or irregular operation, constitutes a predisposi- tion to disease. 13. Causes of disease were formerly divided into remote and proxi- mate: the remote include predisposing and exciting causes, the only circumstances now considered as causes. They were called remote, not because they are distant or not in the body, but because they are not, like the proximate cause, a constant and present part of the dis- ease. The term proximate cause was used by Cullen (after Gaubius) to represent the pathological condition, or essential bodily change, on which the symptoms depend; and it was called a cause of the disease, because diseases were defined by him to be an assemblage of symptoms. But this essential bodily change is a part of the disease rather than a cause, and is therefore better treated under the head of pathology. Discarding, then, the term proximate cause, we have now only to con- sider predisposing and exciting causes. # 14 The co-operation of both these kinds of causes is generally ne- cessary to produce disease. A number of persons are exposed to cold: one gets a sore throat; another, a pleurisy; another, a diarrhoea; an- other some form of rheumatism; and a fifth escapes without any disease at all.' All five were exposed to the same cause, yet it acted differently ali. The first four were predisposed, each to the particular disease, on 38 NATURE AND DIVISION OF CAUSES. which attacked them so soon as it Avas excited by the cold. The fifth had no predisposition, and the exciting cause was therefore powerless; it was insufficient without the predisposing cause, as in the other cases, the predisposition was insufficient until the exciting cause, the cold, Avas applied. 15. In some cases, however, what is in a smaller degree a predisposi- tion may, when it exists in a greater degree, constitute alone a sufficient cause of disease (§ 11:) thus a person Avith a very weak stomach ahvays has indigestion, whether an exciting cause be applied or not. So like- wise exciting causes, if sufficiently strong, may produce disease without predisposition: thus a person not predisposed to indigestion may be pretty sure to earn it, if he take a sufficient quantity of fat, raw cucum- ber, pickled salmon, or any such indigestible matter. Take another example. A healthy person living in a marshy district may not get an ague, until he becemes debilitated by any cause, such as cold, or fa- tigue : then the poison will act. But without his being thus weakened, if the exciting cause be made stronger by his sleeping on the very marshy ground itself, then the poison may act without predisposition, and the ague begins (§ 12.) 16. The consideration of these facts throws some light on the nature of predisposition viewed as a cause. There is in organized beings a certain conservative power which opposes the operation of noxious agents, and labours to expel them when they are introduced into the body. The existence of this power has long been recognised, and in former days it was impersonated. It was the archosus of Van Helmont; the anima of Stahl; the vis medicatrix natures of Cullen. Now with- out supposing it to be aught added to the ordinary attributes of living matter, we may note its operation in the common performance of ex- cretion: we see it in the careful manner in which the noxious products of the body, and the useless constituents in food, are ejected from the system; in the flow of tears which washes a grain of dust from the eye; in the act of sneezing and coughing which remove irritating matters from the air passages; and in the slower, more complicated, but not less apt example of inflammation, effusion of lymph, and those suppura- tive actions, by which a thorn, or any other extraneous object, is re- moved from the flesh. 17. This vis conservatrix (§ 16) is alive to the exciting causes of dis- ease; and in persons in full health it is generally competent to resist them. How it resists them depends on their nature. For instance:__ Is cold the cause? If so the blood is thrown inwardly; and this, ex- citing the heart to quickened action, establishes a calorific process which removes the cold. Is the cause improper food? The preserving power operates by discharging the offending matter speedily by vomit- ing or by stool. Is it a malarious or contagious poison ? It is carried off by an increase of some of the secretions. But if the resisting power (§ 16) be weakened, locally or generally, or if the exciting cause be too strong for it, then the cause acts, and disease begins (§ 15.) 18. In the cases hitherto noticed, predisposing causes consist in ab- sence or deficiency of power (§ 16,) rather than in the existence of anything positive: but sometimes predisposition to disease depends on something positively wrong in function or structure, Avhich yet alone PREDISPOSING CAUSES. 39 scarcely amounts to disease; and this fault may be congenital, or here- ditary, or acquired. 19. It must be observed that predisposing causes operate chiefly through the general system or constitution; hence they are often called constitutional or internal causes, in contradistinction to the exciting causes, which are more commonly external, or acting from without. But these terms are objectionable, because not always applicable. Sometimes the term predisposing is also inappropriate, as in the fol- lowing instance. Several persons are exposed to a malarious or in- fectious poison: some of these afterwards suffer from great fatigue or privation; they then begin to show the effects of the poison: but the others who have not sustained this second influence, escape unhurt. The poison has entered the system in both cases; but in the latter its influence is resisted; while in the former the subsequent weakening so reduces the powers of resistance that the system yields before the ex- citing cause; but occurring after, this weakening cannot be said to predispose. Hence, under such circumstances, the fatigue or privation is called the determining cause. Dr. Carpenter defines a cause to be a "force or power operating under certain definite material conditions,"1 in other words he consi- ders the antecedents necessary to produce a result as being of two kinds, dynamical and material. But these do not necessarily corre- spond with exciting and predisposing causes of disease, for a variation of force may constitute predisposition, and on the other hand altera- tions in material may become exciting causes. The fact is simply that the division of causes ordinarily adopted among pathologists is conventional and convenient rather than natural and philosophical. What are called causes are really circumstances that are essentially and invariably antecedent to disordered action. Some single circumstance may alone be discoverable; or there may be two, three, or more, that have been acting simultaneously, or in succession. It is often conve- nient to specify some of these circumstances as predisposing the body to become diseased, others as determining the disease, and others as ex- citino- or calling it up. But it is not always easy to say which ought to be termed a predisposition, which a determination, and which an ex- citement. The study of pathology and medicine is more difficult and uncertain than the study of ordinary physics, simply because the re- sults observed are nearly always consequent upon a combination of manifold causes, which are always varying in an infinite diversity of ways. Causes follow effects in the vital actions of the living body as certainly and as surely as they do in the working of the dead masses of Nature, but these causes are interwoven in a more complex way, and are subject to many more modifications. The results observed in pa- thology seem to be uncertain merely because the observer has an im- perfect knoAvledge of the antecedents and of their workings. When the properties of organized material, and the actions of living substance are as thoroughly understood as the properties of crude and unorgan- ized matter, the organic sciences will be found to be as precise as Phy- sics properly so called. i "Principles of Human Physiology," 1853, p. 5. 40 PREDISPOSING CAUSES OF DISEASE SECTION II. PREDISPOSING CAUSES OF DISEASE. 20. What for convenience sake we agree to call predisposing causes of disease are circumstances which so influence the functions or struc- tures of the body as to render that body unusually susceptible to the influence of particular exciting causes. Predisposing causes are, how- ever, in strict accuracy, different from predisposition. Predisposition is the state of the body which is brought about by the operation of these causes. Predisposing causes make the body unusually susceptible of certain diseases through predisposition in its structures or condition. Now the most important circumstances that operate in this way may be advantageously considered under the following heads. I. Debilitating Influence. II. Excitement. III. Previous Disease. IV. Present Disease. V. Hereditary Constitution. VI. Temperament. VII. Age. VIII. Sex. IX. Occupation. I. Debilitating Causes of Predisposition are the most numerous of all. This might be anticipated from the fact that constitutional strength generally implies power of resisting disease (§ § 16,17.) The circumstances which are most influential in this way are such as enfee- ble the heart, impair the tone of the arteries, and reduce the activity of the secreting organs: often too an unusual susceptibility of the ner- vous system, which increases the liability of the body to suffer. The following are the chief agents of this class. 21. (a.) Imperfect nourishment, either in consequence of defect in the quantity or quality of the food, or of incapacity of the digestive powers. This in itself causes many diseases, particularly of digestion and nutrition; but it also weakens the power of the general system to resist cold, and produces a liability to low fevers, inflammations, and epidemic, contagious and endemic disorders. Thus the increased sus- ceptibility of the body to the influence of cold and infection, when fast- ing, is generally acknowledged; the rapid propagation of infectious diseases among an ill-fed population, like the poor Irish, is but too well known; and to the disgrace of our nation it must be acknowledged that insufficient and unwholesome food has been one of the unhappy circum- stances that have contributed to render our brave troops in the Crimea an easy prey to disease and death in various forms. The same cause too, especially lays the body open to the injurious influences that in- duce zymotic disorders. The offensive odour of the breath and excre- tions on the approach of death from starvation, proves that there is exemplified and explained. 41 depravation and incipient corruption in the materials of the body, as well as weakness. 22. (b.) Impure air. The injurious effects of this are manifested in the pallid, cachectic complexion of the inhabitants of crowded cities, even of those who live well and regularly. How strikingly this con- trasts with the ruddy countenance of the hardy and coarsely-fed moun- taineer! So are the former also distinguished in the greater liability of these classes to diseases, particularly to those of the organs of re- spiration, circulation, and nutrition. No circumstance seems to ope- rate more extensively in favouring the spread and increasing the viru- lence of such pestilential diseases as the plague, typhus, malignant scarlatina, and the measles, than impurity of air. It effects this in two Avays. In the first place it weakens the body, and so acts as a true predisposing cause. But in the second place it leads to the con- centration and increased virulence of the poison itself, which is diluted and destroyed by the influence of ventilation and fresh air. The im- perfect performance of the processes of respiration and cutaneous transpiration in small and close habitations makes persons offensive both to themselves and to others, in consequence of corrupt matter which ought to be eliminated being left in the system. This makes the soil fertile (so to speak) for the fostering of the seeds of disease, although it may alone be inadequate to the production of disorder. The evil influence of over-crowding human dwellings has been abundantly and forcibly illustrated during the prevalence of epidemic cholera in our own and foreign lands.1 23. (c.) Excessive exertion of body or mind. Moderate exercise is beneficial to both body and mind; but when, either in degree or con- tinuance, this exceeds what the strength can bear or rest can recruit, the animal functions become exhausted, and lose their balance; muscular tone is impaired, nervous excitability takes the place of strength, the circulation fails, congestions ensue, the blood is not properly purified, and the various organs get to the brink of disease. It is hence that the fatigued mind or body is peculiarly prone to succumb before causes of disease. It has been observed in India that regiments were especially liable to be attacked by prevailing epidemic and endemic disorders when suffering from fatigue after forced marches. This has been sadly exemplified in the disastrous results of the siege of Sebas- topol where excessive fatigue in addition to cold and privation de- stroyed thousands of the British army. Want of sleep has a similar effect- and when the body is extremely exhausted, even sleep, which is nature's best restorer, is disturbed by the imperfect performance of circulation and respiration through excess of weakness: hence there is a liability to insomnia and nervous excitement in states of exhaustion. 24 (d ) Want of exercise and sedentary habits generally also fa- vour 'the production of disease. The healthy vigour of the various functions of body and mind is best maintained by equal and moderate exercise • and the torpor of inactivity renders them more obnoxious to the causes of disease. The muscular function, and the circulation of i See Mr Grainger's Report on the state of certain parts of the Metropolis, &c, 1851. Also "British and Foreign Medical Chirurgical Review," January 1, 18o3. 42 PREDISPOSING CAUSES OF DISEASE blood, are the first to suffer; hence first sluggish movements, and ulti- mately weakness, of the heart and other muscles. The defective cir- culation too tells most in parts at a distance from the heart, producing cold extremities, dry skin, inactive liver, with its frequent concomi- tants, haemorrhoids, torpid bowels, and indigestion: whilst at the same time the heart itself, and the organs near to it, may be oppressed and injured by an undue load of blood, especially if the subject be pletho- ric; hence palpitation, dyspnoea, headache, vertigo, somnolency, dul- ness of the senses, &c, &c. In nervous subjects convulsive affections* are often produced by this inequality of circulation. The respiration being little exercised, the task of decarbonizing the blood is imperfectly performed; or devolves more on the liver; hence the accumulation of fat in the textures, and the occurrence of bilious derangements. From this statement it will be obvious that sedentary habits, if excessive, may alone be equal to the production of disease, and that where they exist in less degree they may predispose to its production by other causes, such as irregularities of diet, exposure to cold, violent exertion, &c. From such combination of influences arise various disorders of the digestive organs, heart, lungs, and brain; catarrh, gout, rheuma- tism, calculous affections, diseases of the skin, &c. 25. (e.) Long-continued heat. The debilitating effects of this agent are abundantly exemplified in warm climates and seasons. Under its influence, the muscles, and with them the heart and arteries, lose power and tone; the textures become relaxed; perspiration is profuse: and internal organs, especially the liver, are too much stimulated by blood which has lost more than its usual amount of water, and less of its hydro-carbon. Hence arises a disposition to bilious and liver complaints, dysentery and cholera. _ The function of respiration is much less active in an atmosphere at a high temperature, than when it is cooler. Less oxygen is then taken into the body, and the effete products of decay are less rapidly carried off by oxidation. The odour of the perspira- tion and other secretions thence becomes strongly offensive, and the blood is kept in a state prone for the reception and propagation of zy- motic morbific agencies. Overheated rooms and excessive clothing predispose to disease in the same way by their weakening and relaxing influence. It may be remarked that most of the diseases of hot climates and seasons occur rather at the termination of the greatest heat, than during its steady prevalence, and that therefore this predisposes to, rather than excites, the disease, which is really the immediate effect of cold, or of irregularity of diet, or of malaria. Thus the bilious diar- rhoea and cholera of this country occur chiefly in the early autumn, when the cool of the evening is strongly contrasted with the heat of the day. The chill suddenly arrests the perspiration, and throwing the blood inwardly, oppresses internal organs, especially the liver whose resisting and reactionary energies have been exhausted by the influence of the previous heat: hence coldness of the surface and con- gestion of the liver and portal system, precede the more active symp- toms in flux, cholera, diarrhoea, dysentery, &c. 26. (/.) Long-continued Cold. The experiments of Chossat and others clearly prove cold to be a direct sedative, capable of reducing EXEMPLIFIED AND EXPLAINED. 43 all the vital powers. Cold applied suddenly and for a short time, in- vigorates, because it then induces a healthy re-action, by which the vital properties are exercised and exalted. But when long continued, its own sedative and debilitating effects are permanent: it weakens the circulation, especially that of the surface, causes internal congestions, and directly depresses all the vital energies. The most malignant forms of epidemic fever in this country prevail towards the close of very severe winters; and all diseases then frequently assume a typhoid fype. This is observed chiefly .Among the loAver orders, whose means do not enable them to protect themselves sufficiently against the in- clemencies of the season. We have before adverted to the striking manner in which cold disposes the body to suffer from malaria (§ 19.) 27. (g.) Habitual intemperance in intoxicating liquors. There is probably, in this country, no source of disease more fertile than this. Besides many disorders which are directly excited by it, it predisposes to attacks of fever, erysipelas, dysentery, cholera, dropsy, and rheuma- tic and urinary diseases; and if it do not increase the proneness to in- flammatory disorders, the habit of intemperance certainly disposes such affections to unfavourable terminations, and causes many a victim to sink after accidents and operations, which would have been compara- tively trifling affairs in more sober subjects. Nor can we wonder at the pernicious effects of this kind of excess, when we consider the weakened state of function and structure which stimulating drinks in- duce, especially in the organs which they most directly affect, the sto- mach, the liver, the kidneys, the blood, the heart, and the brain. We shall 'soon have to explain how unsound states of these organs thus in- duced peculiarly impair the powers of the body to resist or throw off disease (§ 17.) . 28 (h ) Depressing passions of the mind, such as par, grief, and despondency. Many are the instances in which bodies of men, as well as individuals, have escaped a prevalent disease, until depressed by some unhappy event or apprehension, and then have fallen victims to it This Avas exemplified in the ill-fated Walcheren expedition, as well as in many incidents in the history of other armies in pestilential coun- tries A defeat, a failure, or even bad news, have made hosts suc- cumb to the pestilence, who had before escaped. It is a common re- mark, that when a contagious or epidemic disease prevails, those who take most precautions frequently suffer most, because they are timid and fearful; the stout-hearted and reckless escape unscathed. Persons whose mental and bodily functions are sustained by confidence and courage, or are excited by enthusiasms, are much less prone than others to suffer from the depressing influence of fatigue, cold wet, ma- laria, and infection. Anxiety and great mental exertion tend to waste the t ssues of the body, and in doing so they not only weaken the frame, but load the blood with excrementitious matter, which may become a nidus for the propagation of zymotic poisons. 99 ({) Excessive and repeated evacuations, either of blood or of some secretion. The weakening effect of a large loss of blood needs rexplanation; but the injurious" influence of habitual losses or drams when these are more than the system .can simultaneously repair, is 44 PREDISPOSING CAUSES OF DISEASE however even greater; for the vital functions then become depraved as well as depressed, a state of cachexia as well as anaemia is induced, and very trifling causes suffice to determine grave states of disease. Menor- rhagia, diarrhoea, leucorrhoea, and other hemorrhages and fluxes, if ex- cessive, reduce the powers of life and the capacity to resist disease. No loss of this nature, however, AA'eakens so much or so irreparably, as excessive secretion of semen. In many of the lower tribes of ani- mals, the males live till they copulate, and then die: the reproduction of the species is at the expense of the individual. That our own species' is not wholly exempt from this law of organized nature, is apparent from the fact that immoderate venery produces extreme debility and premature decay, and predisposes body and mind to various diseases. 30. (j.) Previous debilitating diseases. It is well known that the body is unusually liable to contract fresh disorder during convalescence from serious maladies. It is then weak in all its powers; and the ner- vous system often obtains the ascendency which is common in states of weakness, and which renders the body unusually susceptible to mis- chief (§ 23;) improper food, exertion, excitement, or exposure to cold, at such times readily produce the former or some new complaint. Hence convalescence from a severe disease is a state requiring pecu- liar care. The functions are just resuming their balance, and have neither the vigour of action nor the power of resistance which is the attribute of robust health. The diseases which leave the body most liable to this species of derangement are those ending in exhaustion; as continued fevers and protracted and severe inflammations. 31. II. Hitherto we have considered only those circumstances which predispose to disease through a weakening influence (§§ 16, 17, 20.) There are, however, other circumstances of a somewhat opposite cha- racter, which favour the production of disease through states of ex- citement or activity. Full living, without an adequate amount of exercise, often brings the circulation and other functions up to a high pressure degree of activity without producing disease; there is then re- dundancy of health, and a more than usual capability of resisting those causes of disease which operate by depression, such as cold, malaria, and infection. ^ But there is a predisposition to suffer from causes of additional excitement; thus irritants then more readily induce inflam- mation ; violent exertion causes hemorrhages; and the stimulation of almost any organ may heighten the vital actions to a morbid pitch (§ 5—8.) So, also, unusual vascular activity in a part, although in- sufficient to produce positive disease, may render the part more^liable to'suffer upon the supervention of external causes. Thus the determi- nation of blood to the uterus and mammae at certain periods renders those organs then more liable to disease. Violent exertion makes the muscles, or their fascise, peculiarly prone to rheumatic inflammation on the application of cold and damp. Excessive indulgence in stimulant diuretic beverages, (such as punch,) renders the kidneys liable to in- flammation or _ congestion on exposure to cold. Inflammation or irri- tation of the intestines is not a common effect of cold, but often be- comes so when these viscera are under the exciting influence of a pur- exemplified and explained. 45 gative. _ The brain, if previously over active from hard study, may be excited into inflammation by alcoholic stimulus, or strong moral emotion. 32. III. Proclivity to disease is not unfrequently a consequence of previous disease, independently of the mere weakening influence al- ready noticed (§ 30.) This is particularly instanced in some inflam- matory and nervous disorders. Thus, a child who has once had croup is very liable to its recurrence. One attack of enteritis frequently predisposes to another. Convulsive disorders, such as chorea, hysteria, and epilepsy, are extremely apt to recur; and the longer they have ex- isted, the more difficult are they to remove, and the more ready are they to reappear on the application of any exciting cause. This, which may be called a habit of disease, it is most important to prevent. There can be little doubt that the previous attack, in all such cases, leaves some change of structure or function (§ 18,) which constitutes the pre- disposition, although it may be of a nature to elude our means of de- tection. 33. Under this head may also be arranged many constitutional pre- dispositions to disease which are ascribable to the persistence in the system of a cause of some previous attack rather than to the attack itself. Rheumatism, gout, gravel, many cutaneous diseases, dropsy, and jaundice, may be quoted as examples. A person who has once suffered from any of these is very liable to a recurrence on the appli- cation of an exciting cause; and this is because, although free from the first attack, he may not haAre lost some functional or structural im- perfection (§ 18) which was the predisponent to that attack, and which may therefore again produce a like result upon the addition of an ex- citing cause. In most of these cases the constitutional defect is in some of the processes of assimilation or excretion, and generally of a functional nature, but occasionally it is also attended with change of structure, especially in the great eliminating organs, the liver, the in- testines, and the kidneys. Nor can we separate from this class of constitutional causes certain (§ 32) predispositions to structural disease, of a tuberculous and ma- lignant nature. Where products of this kind have once appeared, there is a tendency to the production of more, although such tendency may be latent until brought into activity by an exciting cause. In the fol- lowing pages many arguments will be found which favour the view that the disposition to such disorders is connected with faulty functions of assimilation and excretion. 34. IV. Disease already existing in the body, even when itself latent, often predisposes to other disorders, independently of its mere weakening effect. (§ 20.) Thus tubercles and other tumours, struc- tural lesions of the heart and other organs, often induce irritations or obstructions of blood-vessels, which, if not the cause of immediate and manifest disease, nevertheless lead the way to the production of disor- der by other causes. A person on the occasion of violent bodily exertion (vocal or otherAvise) is seized with profuse spitting of blood, which causes his death: on opening the body many tubercles are found in the 46 predisposing causes of disease. lungs, although there had been no obvious symptoms of their existence before the violent effort. Or, again, disease of the heart causing ac- cumulation in the veins, often leads to congestion of the lungs and liver; and it may only require the addition of an exciting cause, such as sudden exertion or an excess in diet, to bring about an attack of asthma or jaundice. These are instances of causes coming into opera- tion by accumulation. Granular disease of the kidneys, which impairs the excreting power of these organs, renders the body more liable to suffer disease through the operation of infectious and other poisons, as well as of other exciting causes. Febrile and inflammatory diseases often leave in the body more or less of effete material, which is prone to decomposition, and which sets up derangement in the blood, skin, mucous membranes, and other structures, on the application of any trivial exciting cause, thus causing eruptions, fluxes, and analogous mischief.—The dregs of one malady, in this way, prepare the body for the occurrence of a second. Dr. Carpenter1 has recently pointed out a probable modus operandi of the predisposing causes of Zymotic disease, (see Section IV.) which connects itself with the matters under consideration. Such disorders as puerperal fever, erysipelas, yellow fever, eruptive fevers, cholera, and dysentery are observed to be most readily propagated, as well as to assume more grave characters, in proportion as an albuminous material prone to decay, abounds in the body, whether it be introduced from without, or result from the disintegrating processes of the system; in either case being retained in consequence of the imperfect action of the excretory or eliminating apparatus.—Such decomposing principle (then in fact equivalent to a diseased condition of the fluids) becomes a predisposing cause of disorder, and renders the body obnoxious to infection from the influence of the slightest amount of morbid poison. This is well seen in puerperal females: when the uterus is undergoing a process of rapid disintegration in such, it is especially prone to con- tract the state that leads to the disorder known as puerperal fever, from any medical attendant Avho has been in close connexion with the disease either in the living or dead subject. Those Avho are suffering from accidents or surgical operations are in the same way liable to catch erysipelas and a peculiar form of adynamic fever, which are, ac- cording to Professor Simpson, capable of being carried from patient to patient by the hands of the surgeon, and which are then capable of producing the same morbid states in other subjects. The debilitating influences already noticed, imperfect nourishment (§ 21,) impure air (§ 22,) excessive exertion (§ 23,) and habitual in- temperance (§ 26,) predispose to Zymotic diseases, not only by their general depressing agency, but also by impairing the condition of the blood, and by increasing in it the quantity of an azotized matter in an incipient stage of corruption, and serving as an appropriate nidus for the propagation of a morbific poison. In all cases of this kind, the predisposition must be referred to a morbid state already present in the system. 1 "British and Foreign Medico-Chirurgical Review," January, 1853. TEMPERAMENT—AGE. 47 35. The predisposing causes hitherto considered may be called acci- dental or acquired. There are, however, other influences which are present in the individual at birth; and yet others which arise from cir- cumstances of age or growth. All these may be referred to something defective or ill-balanced in the organization (§ 18,) but which is in- sufficient to manifest itself actively until wrought upon by an external exciting cause. 36. V. Of the predispositions present in the individual at birth, the most generally recognised is hereditary tendency to disease. It is well known that scrofula, gout, rheumatism, epilepsy, mania, asthma, blindness, and deafness, run in families. That this depends on indi- vidual peculiarities transmitted from parents to offspring, appears from the fact that all children do not partake alike of the disposition. Nay, sometimes a generation is free from a disease, which was present in the ancestor and appears again in the offspring. So too we see external organization, family likeness, differently stamped on different children of the same family. It must not be supposed that hereditary proclivity to disease com- mences at birth. In a few instances it is congenital; but in a greater number it is developed by growth or some other circumstances in life. Gout, for example, is acknowledged to be hereditary; a parent has it in middle or advanced life: the son does not get it until about the same period, a little sooner or later, according to whether he lives freely or not. Here is something which is transmitted from father to son, and yet not manifest in the son for forty or fifty years. 37. VI. Frequently, but not necessarily, connected with hereditary conformation, is the peculiarity of constitution called temperament, which certainly predisposes to particular diseases. Temperament con- sists in a predominance or defect of some function or set of functions, viewed in relation to others (§ 9.) . „ , 38. Thus the sanguine temperament implies an activity of tne sys- tem which circulates florid blood, and a full proportion of red corpus- cles; it is manifested by an excitable pulse, flushing cheek, quick move- ments, and lively disposition. This temperament gives a predisposition to inflammation, determination of blood, and active hemorrhage (30.) 39. The phlegmatic or lymphatic temperament is the reverse of the sanguine : it occurs in those who have a weak pulse, languid circulation, cold extremities, and pallid skin,—there is a deficiency of florid blood, and of vascular action and tone (§ 9,) and the proclivity is to watery fluxes, dropsy, and other chronic affections. 40. The bilious or melancholic temperament, is commonly met with in persons of dark complexion and gloomy disposition; there is proba- bly here defective action in some of the biliary or digestive organs, which are therefore the more liable to derangement (§ 9-) 41 The nervous temperament is externally manifested only by agi- tation or trepidation of manner; it seems to depend on an excess, or want of right proportion, of some of the properties of the nervous sys- tem (§ 9 ) and predisposes to the disorders called nervous, such as hys- 48 predisposing causes of disease. teria, nervous pains, and spasms. These temperaments may be va- riously combined. The word diathesis is often used to express a particular morbid tendency; thus we hear of the inflammatory diathesis, the scrofulous diathesis, &c. It is merely another word for disposition, and affords no clue to the nature of the thing spoken of. 42. VII. The last group of predisposing causes to be noticed re- lates to age. The several changes in organization, as well as in ex- ternal circumstance, which the animal frame undergoes at different periods of life, may naturally be expected to be attended with corre- sponding variations in the proclivities to disease. I proceed to enu- merate a few of these, premising that some of the examples may be entitled to rank with exciting causes of disease, as well as with pre- dispositions. 43. (a) In early infancy, the low calorific power of the body dis- poses it to suffer readily from the bad effects of cold (§ 17,) whence the tendency at that time to visceral inflammations. The skin is particu- larly liable to various eruptions in consequence of its tenderness and its not being habituated to the new and drying medium in which it is placed. The redness of neAV-born children is obviously the result of the irritating action of the air; it often assumes the form of a vivid erythema, and is followed by desquamation of the cuticle, and a yellow stain of the skin beneath, from extravasated hsematosin, which is some- times erroneously thought to be a kind of jaundice. Strophulus and other papular eruptions often succeed. The comparatively unused state of the alimentary canal at birth renders it also peculiarly suscep- tible of disorder; another trial awaits it at the period of weaning— hence arise diarrhoea, vomiting, colic, waterbrash, atrophy, and other ailments connected with disordered digestion. The brain, excited by the novelties of the external world, becomes rapidly developed, and, in its increased activity and growth, is rendered liable to various diseases, (§ 30;) hence the proclivity to hydrocephalus, convulsions, &c. The process of teething adds an irritation, which acts on the nervous system, the bowels, and the air passages, and disposes them to get readily dis- ordered. 44. [b) In childhood, or the age from infancy to puberty, the func- tions most active are such as administer to growth: the organs of digestion and assimilation are therefore obnoxious to disorder (§ 32;) hence the frequency of derangements of the stomach and bowels, worms, infantile remittent, &c. The activity of the nutritive function gives a preponderance to the protein constituents of the blood; and inflamma- tions which incidentally occur are commonly attended with the effusion of much plastic or albuminous matter; as seen in the products of croup, and mesenteric disease, tubercle, &c. The natural mobility (or activity of the excitomotory system) of childhood predisposes to chorea and kindred affections (§ 30.) 45.^ (c) Puberty brings with it many morbid susceptibilities, but especially in the female sex, in which the important function of men- struation is then established. Many and serious are the evils which advancing age. 49 are liable to be produced by external causes, that tend to check the development of this function. This function Avhen established has its nervous as Avell as its vascular relations; and hence, where it is irregular or disordered, a predisposition is given to many maladies affecting the blood-vessels and their contents, the secreting organs, and the nervous system. 46. (d) At the termination of growth, there is another critical period. The cessation of the appropriation of nourishment to the increase of the body, may, in the more robust, cause fulness of the vessels, and a disposition to hypertrophy, hemorrhage, and inflammation; and in the cachectic, it may lead to morbid depositions, especially of the tubercu- lous kind (§ 47.) The same redundancy of the vivifying fluid in active circulation, gives that buoyancy of animal spirits and impulsive energy of feeling and strength, which are the characteristics of healthy youth ; yet this very exuberance of vital power, if not properly controlled and balanced, constitutes a tendency to disease; either directly, as where excitement, rising beyond the limits of health, borders on morbid ac- tion (§ 31;) or indirectly, as where excessive exertion leads to subse- quent exhaustion (§ 23.) Youth is the age of susceptibility to moral and physical impressions; and therefore of liability to the disorders Avhich these are capable of producing. 47. (e) Adult age can hardly be said to predispose to any diseases, unless it be such as arise out of the mode of life then pursued. It is commonly a period of comparatively steady health, because the func- tions are then very evenly balanced^; but if the mode of life be un- favourable, bad habits are apt to become established, and by their con- tinuance to induce disease. Thus gout, gravel, rheumatism, indigestion, and various other disorders, are apt to occur in middle life, because the predisposition to them is then gradually engendered (§ 24) by some error in diet or regimen, too slight to excite disease at once, but suffi- cient by accumulation to dispose to it, and so to alloAY of its being manifested on the application of some exciting cause. As age advances, such habits as overstrain and exhaust the strength of the organs, begin permanently to affect the organization, accelerating those changes by which human existence is limited to a span of years. This occurs sooner in proportion as the powers of the system have been expended by hard and irregular living, bodily hardships or mental anxiety, and later accordingly as prudence and moderation have been the guides: different people manifest marks of senility, and senile dis- position to disease at very various periods of their lives. It would occupy too much space to enter into a detailed account of these changes, but some of the principal of them may be briefly noticed, as illustrating the peculiar weaknesses and liabilities of advanced age. 48 (f) The changes which old age induces in the exterior of the body'are connected with a failure of those functions which are most active in youth. Instead of muscles, fat, and integuments being nourished in the several proportions that give beauty as well as strength to the form in mature life, the muscles get thin and sinewy; fat be- comes scanty, partial, or in excess; the integuments are loose and wrinkled, or fat and flabby; the joints stiffen, and the gait loses its 4' 50 predisposing causes of disease. firmness and uprightness. These changes in the textures of the body are attended, and probably induced, by altered relations in the different parts of the vascular system. The pallid skin of age, contrasted Avith the ruddy -blush of youth, indicates the diminished development of the capillary blood-vessels, that great system, Avhich sustains the life and nutrition of the body; much of the blood that in earlier age circulated on the surface, giving vigour and sensibility to all the external organs, and life and susceptibility to all outward relations, becomes accumulated in the interior, and confines its vivifying and nutrient influence chiefly to the internal functions and structures, thus tending to render the in- dividual more isolated and selfish. But the blood that is kept back in the larger vessels, is not equally distributed within them. The di- minished capillaries intercept some of the force by which the nutritive fluid is propelled through the arteries: hence it stagnates and accumu- lates in the veins, which become distended and tortuous; but the ar- teries, being at the same time exposed to the continued impulsive force from the heart, lose much of their elasticity, and become rigid tubes, thus causing the peculiar hardness of the senile pulse. The nutrition of the textures generally fails, not in degree only, but in kind also, and chemical transformations and deposits begin to show themselves in the different structures. The fibrous and muscular tissues exhibit partial conversion into fatty matter, and osseous or petrifactive changes encroach on many structures of low organization; there is a tendency to degradation towards the composition of mere vegetable and mineral matter. This altered condition of the blood-vessels brings with it morbid ten- dencies, the nature of which will depend much on the state of the great moving power, the heart; noAV more than ever the prime agent in the circulation. If the heart bemoderately strong, a fair balance may long be sustained; although hemorrhoids, varicose veins, and such results of local obstructions, may occur. If the heart be too strong, (which is often the case after a life of much muscular exertion,) the small ar- teries frequently suffer from the unsoftened force of its pulses, par- ticularly in the brain, and there is a liability to apoplexy or palsy: the same thing in mucous membranes forms a disposition to active fluxes, catarrh, asthma, and affections of the urinary organs. The more vas- cular textures, especially of internal organs, are over nourished, and increase in size or weight. If the heart be Aveak or diseased, there Avill be imperfect circulation and tendency to venous congestions, drop- sical effusions, imperfect and disordered secretions, altered nutrition and a general failure of all the functions which depend on a sufficient supply of arterial blood: diseases of the liver, stomach, kidneys, lungs and other viscera arise in this Avay: in extreme cases the lower extre- mities actually die for want of circulation. If instead of the organs of circulation we were to take the alimen- tary, the respiratory, or the urinary apparatus, we should also here find changes induced by age, which show that man's organization is only intended to last a limited time. Old age is thus attended with increasing infirmities and liabilities to disease (§ 16, 18.) The very strength and activity which some functions retain, may, in consequence OLD AGE—SEX. 51 of their partiality, endanger life; but their gradual and more equal failure degrades the physical, and often the mental, frame of man to a lower scale of existence, until he sinks into second childhood, dotage, and decrepitude. 49. VIII. Sex. The liability which sex gives to the diseases of the respective generative organs is too obvious to need mention. But the peculiarities of sex are not confined to the generative organs: they extend to many other of the structures and functions of the body. The male sex is peculiar in the higher development of the muscular and voluntary excitomotory system, and a corresponding strength of frame;—in the stronger impulses of the animal passions; and in the greater endowment of the reasoning faculty. These respectively bring Avith them a liability to suffer from diseases of the muscles, limbs, joints, heart, and great vessels;—from the evils contingent on undue indul- gence of passion or appetite; and from disorders of the brain and its intellectual functions. In the female sex the predominant bodily functions are the nutritive, the sensitive, and the involuntary excitomotory; and the perceptive and instinctive faculties, and moral emotions, preponderate in the mind. Hence the greater proneness of females to changes in flesh and blood; to disordered sensation, spasm, convulsive and other affections of the spinal system; and to the direct and indirect consequences of indul- gence or thwarting of instinctive moral feelings. The predisposing influences of the menstrual function have been before noticed (§ 45;) it may now hoAvever be added, that its cessation favours the develop- ment of various diseases of function and structure, especially growths, simple and malignant. 50. IX. Occupation comprises many circumstances already no- ticed under the heads of predisposing influences. Thus, sedentary occupations imply want of exercise (§ 24,) and sometimes impure air (§ 22;) laborious employments operate like excessive exertion (§ 23;) other occupations predispose to disease by the continued exposure to heat (§ 25) or cold (§ 26.) Some employments require constrained postures, which if insufficient to induce, may yet promote the occurrence of disease; thus engravers and watchmakers are liable to affections of the head, because they hold it low; shoemakers and tailors are subject to disorders of the stomach, because they compress it during their work. In many other instances particular occupations induce disease rather by exposing the individuals to the exciting causes, than by in- ducing a predisposition; but as before remarked, the very circumstances, which, when in great intensity suffice to excite disease, Avhen acting in a lower degree may only induce a disposition to derangement. Thus the slow introduction of lead into the system, so commonly occurring in the occupations of painting, plumbing, card-enamelling, and printing, may not cause colic until cold or irregularity of diet becomes an addi- tional or exciting cause. The same remark applies to dry grinding, needle-pointing, leather-dressing, and other unhealthy occupations. The time during which such employments are pursued is an important element in the result; thus an occupation, not in itself unhealthy, may 52 EXCITING CAUSES OF DISEASE, become so when continued too many hours in the day; and a work which is attended with risk may be often safely undertaken for short periods, a due amount of relaxation or diversion to another pursuit being allowed between. By attention to this point, the injurious in- fluences of occupations may be much lessened. SECTION III. EXCITING CAUSES OF DISEASE. 51. We now pass to the consideration of exciting causes of disease; that is of such circumstances and agents as seem to be operative in producing disease in the body, more especially when in a state of pre- disposition (14.) It has been stated before (§ 11, 15,) that certain powerful agents, of the nature of irritants or poisons, pretty surely cause disease, independently of peculiarity of constitution or predispo- sition; but peculiar constitution or predisposition may even then modi- fy the character of the disease in different cases: where the exciting agents are less powerful, as in the case of most common causes of dis- ease, the effect depends still more on the influence of predisposition, and may be altogether inappreciable Avhen this is not strong (§ 15, 19.) Exciting causes of disease, then, are certain external circumstances which have been observed to be very frequently present when certain diseases occur. Because the diseases seldom appear unless these cir- cumstances have been present, they have come to be considered as es- sential to the result, and in the light of excitements to it. Hence they are designated exciting causes. Now such influences may be con- veniently distributed into two divisions, as cognizable and noncog- nizable agents. The former class comprehends physical and mental influences, of whose existence we can take cognizance, independently of their operation in producing disease; thus cold we know by its ef- fect on our instruments and organs of sensation; muscular exertion, by our witnessing or making it; and mental emotion, by our conscious- ness of it. The noncognizable causes, on the other hand, elude our senses, and Ave infer their existence only from their morbific effects: thus malaria and infection are only observed in their morbific results. The subjoined table specifies the different kinds of influences that are comprised Avithin these several divisions. 1. Mechanical influences. 2. Chemical influences. 3. Ingesta. 4. Bodily exertion. , Cognizable , 5. Mental emotion. Agents. j 6. Excessive evacuation. | 7. Suppressed or defective evacuation. I 8 Defective cleanliness, ventilation, and drainage. [ 9. Excesses and changes of temperature. Exciting Causes of Disease. II. Noncognizable Agents. Endemic Epidemic Infectious Poisons. MECHANICAL AND CHEMICAL. 53 I. COGNIZABLE AGENTS. 52. (1.) Mechanical causes, which injure structure; or impede, or derange function. Besides the obvious instances afforded in tear- ing, cutting, pinching, striking, and straining, which produce at once diseases that fall within the province of the surgeon, there are also many mechanical sources of mischief that come under the physician's notice. Long-continued pressure of articles of clothing sometimes produces disease. Tight neckcloths may cause headache or even apo- plexy, by impeding the flow of blood from the head. Tight stays may produce fainting, by pressure on the heart and great vessels, and colic and costiveness and other disorders by obstructing the free passage through the great intestines. Pressure on the epigastrium after a meal, caused by sitting at a desk, may excite indigestion. Long con- tinuance in one position, whether standing, sitting, or lying, tends to obstruct circulation and innervation, and to produce swelling and paralysis of the parts of the body that are beyond the seat of pressure, and this in time may even cause inflammation and death of the parts pressed upon. But mechanical causes may also be operative within the body. A stone in the bladder irritates by its mechanical proper- ties, especially if it be of an angular shape; or it may mechanically stop the flow of urine: so also may a gall stone stop that of the bile. The intestinal canal is sometimes mechanically obstructed by hardened feces, until irritation and inflammation ensue. The stomach is often mechanically irritated by the bulk, hardness, or asperities of its con- tents: and vomiting, indigestion, or inflammation of the organ, may be thereby induced. The air passages of needle-pointers, stone-masons, &c, are irritated and inflamed, and at length become altered in structure, in consequence of the mechanical action of particles of stone or other substances, Avhich these men inhale in the course of their em- ployment. Instances of this kind are endless: certain of the structural effects of disease also exercise considerable mechanical influence. Tumours, diseases of the heart and vessels, the lungs and air passages, intestines, and urinary apparatus, and injuries and diseases of the bones and liga- ments, afford abundant illustrations of this mechanical causation of disease. Some mechanical injuries, when extensive, besides their simple ef- fects on structures and functions, directly depress the vital powers; thus, concussion of the brain, crushing or tearing off a limb, or a blow on the epigastrium, induces fainting and extreme weakness of the heart's action, and may thus even cause death. Slighter mechanical injuries are causes of irritation or excitement, which may be local or general, according to the excitability and extent of the part irritated. 53. (2.) Chemical causes of disease are even more Araried than me- chanical, because the several chemical agents are more numerous than the mechanical. We are acquainted with the chemistry of the animal body less than with its mechanism; and therefore can the less clearly distinguish causes which act by chemical properties, from those which have complex relations to vital properties, than we can those which are 54 EXCITING CAUSES OF DISEASE. mechanical. But we recognise chemical irritants in acids, alkalies, and many salts, whether applied to a part, or inhaled in form of gas or vapour. So what are called chemical poisons, such as corrosive sub- limate and other metallic salts, the strong acids and alkalies, iodine, chlorine, &c, produce disease by their knoAvn powerful chemical affini- ties, which tend to decompose tissues and disordered functions. We cannot doubt that many of the matters which cause disease in the alimentary canal, do so by virtue of their chemical qualities. The process of digestion, although always in part chemical, is so under the superintendent influence of a superior vital power: no sooner does this power fail, or the chemical agencies or decompositions become too strong for it, than we have fermentation and putrefaction, which cause eructation of gas or sour liquid from the mouth, and there may follow the discharge of ill-coloured and unusually fetid matters by stool; then, too, may arise a number of disorders, which may in great part be re- ferred to the influence of these injurious chemical processes. There appear to be at least four modes in which chemical agents may excite disease in the body:— 1. By acting as local irritants, as do the diluted acids, alkalies, and various salts, the chemical operation of which is resisted by increased action excited in the part (§ 16.) 2. By acting as corrosives, as in the case of strong acids, alkalies, some metallic salts, chlorine, and iodine, which by their powerful che- mical affinity, so completely overcome the vital affinities of textures as to decompose them and thus to kill and alter the condition of the part. 3. By acting as septics, promoting the decomposition of the fluids or solids of the body, in the same way that ferments or putrescent mat- ters operate on dead organic matter. 4. By acting as chemical alteratives, modifying the changes which take place in digestion, assimilation, transformation of textures, secre- tions, &c, as instanced in the counteraction of acidity by alkalies, in variously influencing the state of the blood and urine by acids, alka- lies, &c.; and in causing the production of hippuric acid in that excre- tion, by the administration of benzoic acid, and the increase of the solid constituents of the urine by the administration of salt, in the in- crease of the sulphates by the exhibition of liquor potassse, (Parkes;) &c. The operation of chemical agents on the general system will vary according to the intensity of their action, and the extent of their ap- plication. Irritants, if extensively applied, cause feverish excitement. Corrosives, if acting widely, depress the vital powers, like the shock of violent mechanical injuries (§ 52;) if more partially, the vital powers are excited to resist them, thus corrosives operate as irritants. Septics if very powerful, may speedily overAvhelm the preserving vital powers of the body, which then speedily passes into a state of corruption, as in the case of extensive gangrene, pestilential diseases, &c: but if the septic matter be scanty, and the vital powers strong, they are excited to increased action, and the body may by means of accelerated circu- lation, and augmented excretions, get rid of the offensive matter (§ 17 ) Such kind of struggle is instanced in typhoid fevers, epidemic cholera and dysentery, and other toxic diseases, which have received the ap- INGESTA—NON-ALIMENTARY. 55 pellation of zymotic, from the supposed resemblance of their cause to a ferment. 54. (3.) The solid and liquid ingesta are a fertile source of dis- ease, and this in various ways. Their mechanical and chemical pro- perties have already been noticed, (§ 52, 53.) But, they may also cause disease— a. As non-alimentary matters acting injuriously. b. As aliment faulty, or ill-proportioned, in quality. c. As aliment defective, or excessive, in quantity. 55. (a) Of the non-alimentary matters contained in the ingesta, that are capable of exciting disease, salt, spices, pickles, and other condi- ments, and spirituous or fermented liquors, are illustrations. They are all more or less irritating or stimulating to the digestive apparatus; and if used indiscreetly may induce inflammations, congestions, and functional disorders of these organs, and, in some instances, irritation of other parts, and of the whole system. Salt in moderation is bene- ficial as an adjunct to food, both on account of its antiseptic and sol- vent properties, and as supplying a part of the acid for digestion, and an alkali which is required in bile and other fluids: but if in excess, it irritates the stomach, retards digestion, and causes feverishness with thirst. Much of these effects is due to the affinity of the salt for the Avater of the animal fluids, and may be induced by other saline matters beside common salt. Wherever excess of salt is contained in the body, there will be osmosis1 and exosmosis of the liquid amidst the adjoining vessels and tissues until the salt is equally distributed among them, and before this is accomplished, there will be such a diminution of the fluids within the blood corpuscles, and on the surface of membranes, as will rea- dily account for the thirst and disturbance caused in the system. Ac- cording to Liebig, salt impedes the deposition of fat. Animals will not fatten on salt food;—this is a hint for the corpulent. Salt increases the elimination of urine by the kidneys; it has therefore been supposed to hasten the destructive metamorphosis of tissues. The absence of salt in food, especially if this be vegetable, favours the production of worms in the intestines. 56. Alcoholic liquors act as stimulants when taken into the sto- mach. At first they provoke appetite and enable the organ to dispose of a greater quantity of food; but soon the digestive power fails in consequence of the exhaustion that necessarily folloAvs undue excitement, and inappetency, nausea, or even vomiting ensues. The operation of these agents is, however, soon extended, for they are absorbed into the blood, and their stimulant action is exercised on distant parts, espe- cially on the vascular and nervous system. As the absorption is ef- fected by the veins, they pass by the portal vein directly to the liver, and hence the function and structure of this organ are particularly apt to suffer from indulgence in spirituous beverages. So too as the kidneys are the natural emunctories through which extraneous matters are eliminated from the system, they get first over-stimulated, and then exhausted, and are injured in their secreting power, and ultimate- i Professor Graham; "Proceedings of Royal Society," 1854. 56 EXCITING CAUSES OF DISEASE. ly in their structure also, if repeatedly exposed to the same injurious influence. The heart and vessels also are over-excited at first, and afterwards lose their tone: the processes of assimilation and nutrition are impaired and modified, and all the solids and fluids of the body become in some degree depraved. The nervous system suffers espe- cially from the disordering influence of intoxicating liquors. If a lirge quantity is taken at one time, it acts as a narcotic poison, in- ducing a short period of cerebral excitement or intoxication, and then insensibility, in which the functions of the brain are more or less com- pletely impaired, and in extreme cases those of the spinal marrow also; if the influence be insufficient to stop respiration, yet it may so far interfere with it as to lead to congestions in the brain and other or- gans. Hence apoplexy, palsy, phrenitis, or delirium tremens, may follow, and the Avhole frame may suffer from the effects of the poison. Even Avhen less excessive quantities are taken, the headache, sickness, inappetency, and feelings of wretchedness and depression which com- monly ensue, sufficiently prove that grave disorder has been produced, and that such artificial excitements cannot be abused with impunity. Habitual indulgence in strong drinks causes other kinds of disease, which are so often seen that they deserve especial notice. When taken only, or chiefly, Avith food, not as a substitute for it, but as a consti- tuent of general " free living," fermented liquors contribute to the production of an abundance of ill-assimilated, overheated blood:1 which either finds a vent in eruptions on the surface, or in local hemorrhages or fluxes, or causes various functional disorders, such as palpitation, vertigo, stupor, dyspepsia, and bilious attacks, or sometimes produces gout or gravel. The latter results more commonly follow Avhen the beverages contain much free acid, as well as an abundance of spirit, as is the case Avith port wine, rum punch, and hard strong beer. The less acid malt liquors, ale and porter, tend rather to induce liver dis- orders, and an abundant deposition of fat in the body. All these con- sequences are promoted by sedentary habits (§ 24) and deficient ex- cretion: for active exercise carries off much of the spirit and superfluous aliment, by an increased elimination through the aids of respiration and perspiration. The most disastrous consequences of intemperance are exhibited in the habitual drunkard, who in proportion as he indulges in liquor, loses his appetite for food, and his power of digesting it. He then drinks and starves at the same time; and the disease which ensues comprises the exhaustion of inanition together with the more direct effects of the alcoholic poison. Thus in delirium tremens, the drunk- ard's disease, besides the permanent restless excitement of the irri- tated nervous system, which adds more and more to the exhaustion there is fearful weakness of mind and body; and in bad cases even the organic functions are affected, so that the pulse is very weak and fre- quent, the excretions are scanty and depraved, and the respiration is 1 This effect of alcoholic drinks, familiar to all observers, receives additional ill t tions from the experiments of Dr. Bocker, which shows that they tend to dimin sh the urinary excretion, and the elimination of carbonic acid by the lunes —British n„j it Medico- Chirurgical Review, October, 1854, p. 398. S S'1 andJi°™9n NON-ALIMENTARY—FERMENTED LIQUORS. 57 so imperfectly performed by the involuntary powers that sleep cannot ensue. This exhaustion soon terminates in death, unless the result is prevented by appropriate treatment; and this must comprise, besides opium (the common remedy,) ammonia and other stimulants to the circulation and respiration, purgatives and diuretics to free the blood from the excrementitious matter that has accumulated in it; and fluid nourishment to repair its waste. Without these adjuncts, opium will not only fail to procure sleep, but if given in large doses may even paralyze the remaining poAvers of life.1 Pernicious as fermented liquors are in their abuse, yet these and other adjuncts to food when taken Avith careful moderation and dis- crimination, often prove beneficial by aiding the digestion where it is weak, and by counteracting various exhausting and depressing influ- ences, which frequently arise out of the artificial condition and em- ployments of society, especially in large towns and in cold climates. It appears from the observations of Dr. Locker, that alcoholic liquors used in moderation, prove beneficial in restraining the waste of tissues, and therefore in sustaining the nutrition of the body. In this respect its action is contrasted Avith that of Avater and of salt, and resembles that of tea and coffee. (Brit, and For. Med. Chir. Rev. Oct. 1854.) Total abstinence, therefore, is preferable to moderation, in many cases, rather because it is morally easier to practise, than because it is more salutary in its physical effects. Tea and coffee also, although refreshing and really invigorating ad- juncts to food when used in moderation, may excite disease Avhen taken in excess: the derangements being chiefly those of the stomach and nervous system. Gastralgia, nervous palpitation, or fainting, insomnia, and even mental delusions, have been induced by the too free use of strong tea or coffee. Even water, the simplest, and it might be thought the most harmless of beverages, is not without its positive influence on the animal economy, and if taken in excess, is capable of producing considerable disorder. Besides its effect in distending the alimentary canal and blood-vessels through which it passes, it further accelerates the retrogressive transformation of the blood and textures, as is mani- fest by the increase of matter excreted by the kidneys and intestines. (Bocker, ut supra.) It appears, therefore, that water largely taken 1 Long experience has fully convinced me of the danger of an empirical mode of treat- ment in the worst forms of delirium tremens. I have known more than one instance where death has speedily and unexpectedly ensued upon the administration of opium in large doses, ordered to be "repeated until sleep should be procured." When it was procured, it proved to be the sleep of death. Inability to sleep, in this disorder, depends upon the exhaustion of the medullary and nervous powers, as named above, and perhaps also somewhat on the vitiated state of the blood, which gets loaded with decaying and excrementitious matters that the depressed secerning energies are not able to eliminate. Here stimulants, instead of increased narcotization, are the things needed; and even tonics may be of service, combined with nutrients in the form of boups. jellies, and fa- rinaceous foods, and also diuretics and aperients. These should be given during the day, and the opiates reserved for the night; and even moderate doses, under such cir- cumstances, often prove to be efficacious. I have sometimes found better results fol- low from the use of tincture or extract of Indian hemp (which, however, are not always obtainable of definite strength) than from that of opium, for it calms the nervous system and induces sleep, without impairing the appetite or powers of digestion. The tincture of hop, too, is a useful adjunct to other remedies in this point of view. 58 EXCITING CAUSES OF DISEASE. tends to reduce the weight of the body, and impoA'erishes the blood, whilst alcoholic liquors have the opposite effect. 57. Disease may be excited by unwholesome articles with which the food is adulterated. To this class of causes belong various poisons; the operation of some of these will be noticed under the head of Modes of Death (see chapter on Prognosis;) but for further details, works on toxicology and materia medica must be consulted. There are some noxious matters occasionally mixed with food, which produce delete- rious effects very gradually. In this way salted provisions, too long used, cause scurvy: ergotted corn has been known to produce dry gan- grene. Lead gradually introduced into the system causes constipation, colic, paralysis, cachexia, anaemia and atrophy. Impure water used as drink, is a common cause of disease. River or pump water near towns often contains decaying vegetable or animal matters, and induces sickness, diarrhoea, dysentery, cholera, and typhoid symptoms. Hard waters, Avhich are impregnated with some of the salts of lime, render the bowels costive, and are supposed to favour the production of cal- culous diseases and bronchocele: brackish Avaters, containing saline matter, may induce dyspepsia and diarrhoea: chalybeates, containing iron, are constipating and heating.—Any kind of impure water, if long used as drink, may gradually impair the processes of digestion, nutri- tion, and assimilation, even although no obvious disorder immediately results from their use. Under the head of non-alimentary ingesta which may cause disease, we must reckon various medicines: and that not only when injudiciously administered, but even as commonly prescribed: the remedies necessary to cure or relieve many diseases are not uncommonly necessary evils; they remove one disorder by inducing another, and it is well when the evil thus induced is the smaller of the two. It cannot be denied that proofs are frequently met with of the mischievous and morbific effects of the injudicious employment of drugs, and there can be no doubt that many of the boasted achievements of homoeopathy, and other quacke- ries, are really the result of the suspension of the influence of injurious medicinal agents.1 58. (b.) Unfitness in the quality of aliment is another condition whereby ingesta may cause disease. Man is by nature and habit an omnivorous animal; and in general his health is best maintained by an admixture of different qualities and varieties of animal and vege- table food. The insalubrity of the simpler constituents of food, Avhen used separately, even those supposed to be most nutritive, has been 1 Dr. Mann in revising these pages has favoured me with the following illustration:__ "A very interesting case of this kind has just fallen under my notice. I was called last week to se*e a physician, a visitor to this place (Cromer,) for relaxation. I found him in a state of great nervous excitement and trepidation, and full of the idea that he was just going into a state of collapse. On investigating the facts I found he had been taking immoderate exercise in the sun, and eating lobsters and drinking pale ale, until attacked with bilious derangement, and mild continued fever; then he fancied he had suffered from malaria, and that the fever had distinct intermissions, so he dosed himself with quinine. When I saw him he had taken sixty grains of disulphate of quinine in a few hours; the nervous derangement was unquestionably due to the influence of the me- dicinal agent. It was four complete days before the disease thus induced had disap- peared." INFLUENCE OF ALIMENTARY ELEMENTS. 59 well shown by the numerous experiments of Majendie, Gmelin, and others. They fed dogs, geese, donkeys, and other animals, on articles which are generally considered highly nutritive, as sugar, gum, starch, oil, or butter: Avhen any of these were given exclusively, the animals died with symptoms of starvation almost as soon as if they had been kept without food. Even bread, when too fine, is unsuitable for exclu- sive nutriment. A dog fed on pure white bread lived only fifty days, Avhereas another fed Avith the coarsest brown bread was well nou- rished, and seemed capable of living an indefinite period. According to the researches of a commission of the French Institute, (the report of which was published in 1841,) animals fed on pure fibrin, albumen, or gelatine, die of starvation, and with reduced quantity and depraved quality of the blood, almost as soon as if not fed at all. Gluten, or vegetable albumen, seemed to be the only simple principle which was able alone to maintain life. The nutritious qualities of vegetable food depend chiefly on the quantity they contain of this azotized principle. Wheaten bread consists of this highly nutritious principle combined with a due proportion of combustible and heat-supplying starch. Hence it is the most sufficient and useful of all the varieties of food, and may therefore well be called the staff of life. Even animal albumen and fibrin require mixture with vegetable matter to make_ them properly nutritious as Avell as wholesome; and gelatine and oily matters are still less available for nourishment without some such combination. In the experiments just alluded to, animals could be supported for a lengthened time on meat or flesh, which comprises several of the ele- mentary principles, although they could not be sustained by any one of these principles given alone. The utility of a due combination of the organic elements in the food used by animals Avas long since sagaciously pointed out by Dr. Prout, who takes the natural aliment of infancy, milk, as the great type of all proper kinds of nourishment; as it contains albumen, oil, sugar, and water, (not omitting certain salts, especially the chloride of sodium, and phosphate of lime,) so all other kinds of food ordinarily used for sustenance ought to include these elements, or others isomeric (that is, identical in ultimate composition) Avith them; and it is certainly true that all combinations of food sanctioned by custom do comprise such ingredients. Bread contains two of them, gluten, which is vegetable albumen, and starch, which is isomeric with sugar; but bread is not relished without butter or some fat with it. Neither does meat, which contains albumen and fat, suit the taste without combination with bread, rice, potatoes, or some vegetable, which represents the amyla- ceous or saccharine principle. The palate likewise craves the addition of a little salt, which promotes the digestion and assimilation of most kinds of food. 59. Much discussion has occurred of late as to the share which each of these constituents of food takes in the actions of the animal economy, and the extent to which they can be changed by the process of digestion and assimilation. Dumas, and the French chemists gene- rally, have maintained that the digestive process only separates and appropriates principles ready formed in the food, and that it does not 60 EXCITING CAUSES OF DISEASE. effect the conversion of one into another. Thus they say that all the albumen or fibrin in the body is derived from the albumen or gluten of the food; and all the fat from fat or oil contained in the nourishment. This view, so far as fat at least is concerned, is opposed by many fami- liar facts, such as the fattening of domestic animals Avith farinaceous and vegetable foods, which contain very little fat; and it has been com- pletely negatived by the experiments of Petroz and Boussingault, which have proved that geese and pigs during the process of fattening gain more fat than is contained in their food.1 It further appears probable that the conversion of sugar into fat is promoted by the agency of bile; for H. Meckel found that by keeping a mixture of bile and grape sugar at a warm temperature, the quantity of fat in the mixture increased to double in five hours, and more than treble in twenty-four hours. It is pretty certain, therefore, that fat may be formed out of starch or the saccharine principle, and probably from the albuminous also, as albu- men gets spontaneously converted into fat under special circumstances. But there is no decisive evidence to show that albumen or gelatine is elaborated from fat, starch, or sugar, at least under common circum- stances; and it is certain that these elements alone do not suffice to sustain animal strength or life.2 Baron Liebig, has, in a very comprehensive hypothesis, suggested that food not only supplies the plastic constituents whereby the waste of the textures is repaired, and their growth supplied, but that it also furnishes the chief combustible principle of the blood, which is burned under the process of respiration for the support of the animal tempera- ture, and thus protects the histo-genetic (or tissue-making) materials from being consumed. Thus whilst albumen, fibrin, and analogous matters are applied to the purposes of growth and nutrition, oil, sugar, starch, alcohol, and allied matters, like gum and vegetable acids, con- stitute merely combustive material, or fuel, Avhich is converted, through the oxidating processes of respiration, into carbonic acid and water, giving out heat during the change. It is certain, however, that fatty matter is, in a degree, essential to nutrition, being a constant consti- tuent of the nuclei and granules of the primary cells of tissues and of nerve substance. So also as starch and sugar are susceptible of being converted into fat by the agency of the liver, they cannot be excluded from the list of nutritive materials. It is scarcely possible to doubt that the increase of weight and muscular strength that accrues from the continued employment of cod-liver oil can be anything else than a result of direct nutrition by means of oil. 60. The chief alimentary matters may be classed into groups, ac- cordingly as they are albuminous, gelatinous, oleaginous, and saccha- rine, or amylaceous: we have now briefly to consider how an excess, or 1 Dr. Day's Report on Chemistry in Dr. Ranking's Abstract, July, 1846, p. 316. 2 In a very able paper on Vital affinities, by Dr. Alison, (Transac. of Royal Soc. Edin. 1847,) many arguments are adduced in favour of the inference that albumen may be formed in the animal body, especially in vigorous health: the author suggests that am- monia may be the source from which starch and other non-azotized articles of food re- ceive the azote that is necessary for their conversion into albumen. There is much reason on the side of this notion; it may be seen that I have long entertained a similar opinion in regard to the conversion of gelatine into albumen. ALIMENTARY ELEMENTS. 61 defect, and in some instances faulty quality, of either of these, may operate in causing disease. Albuminous or proteinaceous articles, such as the lean of meat, foAvl, and fish, gluten of bread, and casein of milk, supply the albumen and fibrin of the blood, and of the textures of the body. Hence deficiency of this kind of nourishment will produce, first, weakness of the heart and other muscles, and then wasting of these, and of other textures, Avith diminution of the quantity and richness of the blood. Failure of mus- cular strength, weakness of the circulation, and wasting of the muscular and other structures, commonly result from insufficiency of albuminous foods. Excess of carneous food, particularly of the richer kind, butcher's meat, tends to oppress and derange the digestive organs, or to cause plethora, with excited circulation and feverishness, Avhich may even result in hemorrhage, inflammation, gout, lithiasis, &c. Bad quality of albuminous food is peculiarly injurious to persons of weak digestive and assimilative powers: thus the casein of cheese, the fibrin of stale or salted meats, and the gluten of sour or ill-baked bread or heavy pastry, may irritate the alimentary canal and cause dyspepsia and diarrhoea, and even Avhen absorbed, instead of forming good protein material, may degenerate into certain products of animal decay, namely, lithic and lactic acids, urea,1 &c. Hence may arise gout, rheumatism, calculous disorders, cutaneous eruptions, Ioav irritative fever and cachexia. Gelatinous foods, soups, broths, isinglass, and jellies, are by no means so nutritious as albuminous matters; but when combined with bread they satisfy hunger and nourish the body so well that it seems very probable that in a healthy constitution gelatine may assist in the formation of albumen; but when used in excess, or to the exclusion of bread and meat, it ceases to be nutritious, and the strength and flesh waste under its use. Oleaginous nutriment, butter, fat of meat, oils, and oily seeds, not only supply the material for the adipose textures of the body, but also assist in the formation of other structures and secretions, (oil globules forming a normal constituent in them,) and afford the strongest fuel for the maintenance of animal heat by respiration. From what has been before stated (§ 59,) it may be inferred that fat may also be formed from saccharine and starchy food, as well as draAvn from the storehouses of the adipose membrane: and from the researches of M. Claude Bernard it appears that the liver has the power of elaborating both fat and sugar out of the constituents of the blood when neither of these principles is supplied in the food.2 Still deficiency of fat in the food has been observed to induce the folloAving morbid results: loss of flesh, and of the rounded plumpness and smoothness of the surface, 1 In this statement I disregard the dogma of Liebig that the materials of food serve for respiration and nutrition only, and that urea, lithic acid and excrementitious matters, are derived from the decay of the tissues alone. Daily observation convinces the medi- cal practitioner that in persons of weak assimilation, certain articles of food, so certainly and promptly cause an increase of animal matter in the urine, that there can be no doubt they are the direct sources of the addition. The observations of Lehmann support the same conclusion. — P/n/no'ogical Chemistry; translated by Dr. Day, 1851, vol. i. p. 161. 2 L'Union M6dicale," 1850. 62 EXCITING CAUSES OF DISEASE. which becomes skinny, wrinkled, and often dry and scurfy; brittleness of the hair and nails; deficient secretion of mucus at the orifices of mucous passages, of cerumen in the ear, and of synovia in the sheaths and joints; insufficient formation of bile, and consequent impaired digestion and flatulent fetid and irregular feculent excretion; with diminution of the power of sustaining animal heat. On this account the privation of oily food is more injurious in cold seasons and climates than in the reverse, often even aggravating the morbific operation of external cold. Excess of fat food may disorder the stomach by its indigestibility, becoming rancid, and causing heartburn or sickness, and sometimes a bitter bilious taste; for much fat seems to induce a regurgitation of bile into the stomach, probably to assist its digestion (Beaumont) and absorption (Matteucci.) If the fat is carried into the blood, it may cause inconvenient obesity by its accumulation in the adipose texture of various parts of the body; or if the subject be natu- rally lean, and incapable of accumulating fat, the superfluity must be got rid of, and the natural emunctories, the sebaceous follicles of the skin, and the liver, then become disordered; hence appear acne and other follicular diseases of the skin, and various bilious disorders. These results are the most readily produced in sedentary persons, in whom the exercise of the lungs is insufficient to consume the superfluous fat. On the contrary, those who use active exercise can often take considerable quantities of fat with impunity, and sometimes with ad- vantage. For similar reasons, oily food is better borne in cold than in hot climates and seasons: thus, as Liebig has pointed out, the Lap- lander relishes train oil, which serves to sustain the warmth of his body; Avhilst the Italian in a sunny climate prefers the less combustible food, maccaroni and fruit, which nourish without heating. The Esquimaux surprise travellers by the enormous quantities of blubber that they can consume; but the Indian is easily satisfied with rice and other light farinaceous vegetables. The quality of oily matter in the food is an important element in its morbific effects; such substances as are most prone to chemical change, or to become solid, are more likely to disagree than others. Thus stale or tainted butter or fats, and rancid oils, are peculiarly offensiA'e to the digestive organs, both on account of the production of injurious acids (butyric and oleic,) and because their thickness renders them in- capable of the minute diAdsion necessary for their absorption and ap- propriation by nutritive process. On the other hand, cream, fresh butter, mild fat, and sweet salad oil, agree well and nourish, especially when intimately blended with farinaceous or succulent vegetable mat- ters: and the cod-liver oil, when fresh and free from rancidity, is borne by the weakest stomachs. It is possible that the easy dio-esti- bility of certain fats is partly due to the facility with which they form emulsions with the pancreatic and other secretions of the alimentary canal. Thus cod-liver oil and the fat of bacon are among those most easily borne on the stomach, and I am informed by Dr. Lyon Playfair that these both possess the important property of saponifying with the alkaline carbonates, Avhereas other oils unite only with caustic alkalies. Amylaceous or starchy foods, such as arrowroot, sago, tapioca, and ALIMENTARY ELEMENTS. 63 many kindred farinaceous preparations, although isomeric (i. e. consist- ing of the same elements) with saccharine matter, are not quite similar in their physiological effects. Like it, they probably supply a fuel for the process of respiration, rather than sustain the body by nourish- ing the textures, and so save them from the consuming influence of the oxygen absorbed through the lungs; and if taken in excess, they may either lead to the formation of fat, (§ 59,) which is deposited in the textures, or passing into fermentation, they may give origin to acetic, lactic, and oxalic acids, and other matters of an injurious kind; this latter effect occurs more often Avith saccharine than with amylaceous food. On the alimentary canal too their effects in some degree differ, excess of amylaceous food impairs the action of the intestines and the secretion of the liver, whereas sweet things often relax the bowels and cause a redundancy of bile. These different effects of saccharine food are probably connected with its occasionally containing, or forming, vegetable acids, which irritate the alimentary canal, and Avhich may thence cause dyspepsia, diarrhoea, diabetes, rheumatism, oxaluria, and other disorders of the same class. Amylaceous and saccharine matters being the mildest materials of food, serve to dilute the stronger articles fibrin and oil, and to render them both more palatable and more digestible; when, therefore, the former are deficient, the latter are more apt to disagree, and to fail to nourish. In common with other vegetable principles, such as gum, vegetable jelly, extractive, &c, they also contain alkalies combined Avith vegetable acids, compounds Avhich are decomposable in persons of strong digestion, the alkali then becoming useful in counteracting the acidity which results from the processes of transformation con- tinually proceeding in the body. On this account fruits, and other vegetables, assist in neutralizing and eliminating lithic acid, and in preventing the occurrence of gout and gravel. This view is in accord- ance with the statements of Prout, Liebig, and Wohler; but I believe it only applies to the case of persons whose digestion is strong; for where this is weak, I find that vegetable acids and fruit commonly in- crease the acidity of the urine, and are therefore injurious:1 whether they do this by passing unaltered through the circulation, or by irri- tating the primse viae, and thus leading to an usual development of hy- drochloric and other unchangeable acids, I cannot say, but the latter course would appear to be the most probable. But there is some reason to suppose that vegetable acids have an influence on the blood before or while they undergo the combustive process; for whether alone or in combination Avith an alkali, they certainly exercise an operation on the body more cooling and antiphlogistic than can result from the alkalies which they contain. Thus sub-acid fruits and drinks are found refreshing and really cooling in fevers; and lemon-juice even in large quantities is now generally acknowledged to be poAverfully antiphlogistic, especially in rheumatic and gouty inflammation. That this property depends on an eliminating power of the vegetable acids and of their salts is possible, but it may be connected Avith some direct chemical 1 This has been confirmed by Dr. Bence Jones, who found that large doses of tartaric acid render the urine more acid than usual.—Phil. Trans., 1849. 64 EXCITING CAUSES OF DISEASE. action by which the materies morbi in the blood is decomposed and thus deprived of its irritating influence. 61. The selection and combination of articles suitable for food would be a difficult task, requiring much scientific knoAvledge and calculation, were it not that Nature has supplied us with a trustAvorthy guide, which happily points out the varied Avants of the system in changes of season and diversities of circumstance. The appetite and taste generally in- struct us pretty safely as to Avhat are the best proportions in Avhich the different kinds of food should be mixed; but they must not be per- verted and pampered by condiments and refined modes of cooking. These expedients coax and deceive the appetite and taste; and if these guardians of the nutritive department are cheated, it is no wonder that the department itself becomes deranged. 62. (c.) Aliment may be excessive or deficient in quantity. Some- times the appetite is inordinate; more frequently it is stimulated and tempted by luxuries; in either case, more food is apt to be taken than the expenditure of the system requires. If the digestive organs fail to dispose of this, they become distended, irritated, and otherwise dis- ordered by the undigested part, and the various symptoms of indi- gestion appear, or perhaps oppressed breathing, palpitation, congestive and convulsive attacks, gastritis, enteritis, colic or diarrhoea. If the digestive organs are strong, and digest the excess of food, they send too much chyle into the blood, which then over-distends the vessels, and deranges the functions of assimilation; hence may result plethora, apoplexy, gout, gravel, or some congestive hemorrhage or inflammatory disorder, to Avhich the individual may have been predisposed (§ 14.) Such evil consequences of repletion ensue the more readily in sedentary persons, in whom the Avaste of the body is small, and the excretions are scanty. 63. Defective nourishment excites various disorders. In the extreme case of absolute privation of food the cravings of hunger alternate Avith nausea, and a sense of sinking: then follow extreme depression, tran- sient fever, delirium, general disorder of both body and mind, increasing feebleness, and inability to maintain animal heat. It is a curious fact, that in this state the stomach sometimes becomes inflamed; probably from the irritating action of its OAvn secretion on the unrelieved vessels. Even in the slighter degrees of abstinence, enjoined by the physician in the treatment of disease, symptoms of vascular and nervous irrita- tion often arise in the midst of general weakness. By many practi- tioners of the Broussaian school, these symptoms are erroneously taken to be indications for greater rigidity in the antiphlogistic plan, whereas a judicious and cautious return to a nourishing diet is really required, and will prove the best cure. Deficiency of food ultimately causes general Aveakness of the functions and Avasting of all the textures, but least of those of the nervous system. The blood becomes thin and easily extravasated; the gums spongy and bleeding; fat disappears; the muscles get thin and flabby; the legs become cedematous; diarrhoea often occurs; ulcers appear in the cornea, and other parts which are the least vascular; and a state of scurvy, or cachexy, is induced, from Avhich an improved diet may noAV fail to restore; for the powers of di- EXCESSIVE BODILY EXERTION. 65 gestion and assimilation sink with the other functions, and it is only by very gentle and careful management that they can be reinstated when very far gone. Another result of the general depression caused by inanition is the impairment of the action of the excretory glands, in consequence of which effete and decayed matters which ought to be thrown out of the system are retained, and produce fetid breath and offensive effluvia, as observed in persons who fast long or are ill fed. Doubtless, too, the lowered vitality of the tissues then renders them little able to resist the tendency to decomposition, and hence there is ready decay and interstitial absorption. Chossat found that in ani- mals gradually starved to death the temperature progressively declined, so that unless it were maintained artificially, the animals seemed to die of cold. All the textures, even the bones, sustained great loss of weight; but the substance of the nervous centres wasted far less than that of any other organs. This fact I should be inclined to attribute to the peculiar condition of the blood-vessels supplying these centres, which enables them to monopolize the little blood remaining; in this we find a ready interpretation of the predominance of nervous symptoms in persons suffering from inanition. (See Ansemia.) In less extreme cases, poor living may excite scrofulous and tuberculous disease, and other kindred forms of degeneration of organs. The bad influence of poor living is much more expressed in those who are confined in close habitations, such as prisons, poor-houses, the cabins of ships, and be- sieged towns, than in those who are at large (§ 22:) and it is under such circumstances that the insalubrity of some kinds of food, however nutritious in general, becomes apparent. Thus even bread, with meat, or broth, will not preclude the occurrence of scurvy; but a sufficient addition of fresh vegetables, even if they be only potatoes, prevents this disease from appearing.—(Dr. Baly, Med. Gaz., Feb. 1843.) It has been observed that pestilential diseases of the most destructive kinds ensue after a period of famine. It is the ill-fed of the popula- tion that mainly succumb to epidemic, endemic, and infectious disor- ders. Dr. Carpenter well suggests that this may be at once explained, when it is remembered that in the body during starvation there is, not merely that general depression of vital powers which may be a predis- position to almost any kind of malady, and pre-eminently to such as are of a zymotic nature,—but also the presence in the blood of an un- usual quantity of disintegrating matter, which forms the most favour- able nidus for the reception and reproduction of morbific poisons.— (Principles of Human Physiology, 4th Edit., 1853, p. 397.) 64. (4.) Excessive bodily exertion is a common exciting cause of disease. General muscular efforts, as in running, walking up hill, roAving, &c, hurry the movement of the blood back to the heart, and resist its distribution through the arteries to such an extent that the heart, the lungs, the brain, and other organs, have an unusual pressure upon them (§ 51.) Disease is then readily induced, especially in per- sons little accustomed to this kind of exercise (24.) The heart, when excited to inordinate action, is often strained and distended, and its function, or even its structure, as well as that of the 5 66 EXCITING CAUSES OF DISEASE. great vessels, may be impaired in consequence. This is especially apt to happen if there be anything already wrong in the structure of the organ, its valves or vessels; and independently of actual disease there are naturally very various degrees of perfection and strength in these parts. The brain is particularly liable to suffer from violent exertion, espe- cially if joined with a stooping or constrained posture; for its vessels are not, like those of the limbs and trunk, supported by muscular pres- sure, and the excited heart on this account sends its blood into them with more force. Hence confusion of the senses, giddiness, noise in the ears, deafness, defective vision, convulsions, palsy, and apoplexy, are sometimes brought on by violent exertion. The lungs too are apt to suffer; for the blood being returned to them faster than they can arterialize it, they become greatly congested y cough, dyspnoea, haemoptysis, or inflammation of the lungs, ensue in this way: the texture of the lungs sometimes also sustains injury in consequence of the violent strain to which it is subjected by the in- creased exertions made in sustaining the breathing, and temporary emphysema is produced. Other internal organs are sometimes disordered by the blood thrown into, or retained in, their vessels by the pressure of external muscular action. Derangement of the liver, haematemesis, hemorrhoids, and hasmaturia, have been brought on by such means. The sharp pains or stitches felt in the sides or abdomen on running fast are commonly sup- posed to be in the liver or spleen: but more probably they are spasms of the intestines—temporary colic,—produced by irregular pressure on them, when their sensibility is raised in consequence of an undue quantity of blood being thrown into them. Some kinds of muscular exertion peculiarly affect certain organs. Thus loud reading, or speaking, or blowing wind instruments, especially tries the organs of respiration and voice, and may cause hemorrhage, inflammation, and various diseases of these structures. Excessive or rough riding or leaping may injuriously affect the kidneys and organs of generation. Straining to lift a heavy weight, or at stool, or in any continued effort, which implies holding the breath, endangers the struc- ture of the vessels of the chest and brain, on which there is no equally counteracting muscular pressure exerted at the time. Long continued bodily exertion may also cause disease by its ex- hausting effects. In extreme degrees this exhaustion may amount to syncope, and even death: short of this, it may cause great weakness of the muscles and of the heart, with corresponding depression of other functions, congestion of the Adscera, and defective assimilation and ex- cretion: hence arises the low typhoid, or adynamic fever, which some- times follows prolonged fatigue. In these cases the chief disorder must be considered to be in the blood, Avhich becomes loaded with the de- 1 Some of the most severe cases of pneumonia that I have ever had to treat have occurred in boys at public schools after violent and long-sustained exertion at football, and other athletic games. These cases all closely resembled each other, being eminently conges- tive, and accompanied by much depression in the early stage, and generally affecting both lungs; yet in spite of the formidable character and extent of the disease in these cases, they have in almost every instance recovered. AATANT OF EXERCISE—MENTAL EMOTION. 67 caying matters that result from the disintegration of the muscular and other tissues, and which takes place more rapidly than the antagonistic processes of elimination and reparation. In slighter cases of great fatigue there are giddiness, faintness, nausea, loss of appetite, indiges- tion, costiveness, amenorrhoea, and Other varieties of injured function. When muscular exercise is carried on so long, or to such a degree, as to impair the organic functions, it thereby induces disorder in them in addition to the weakness, prostration, and actual suffering in the ani- mal functions. A serious part of such disturbance is the sleeplessness which, in extreme fatigue, brings the patient into a state nearly re- sembling delirium tremens. This, as we have already mentioned Avhen speaking of predisposing causes (§ 23,) is mainly due to the state of the respiration, which being insufficiently maintained by the weakened spinal function, is aided by continued voluntary efforts, manifested in the frequent sighing that takes place. In these conditions diffusible stimulants are the best hypnotics. 65. The opposite extreme, want of exercise, is capable of exciting as well as predisposing to disease (§ 24.) Thus internal congestions, deficient and disordered secretions, general plethora, over nourishment of adipose texture, and wasting of muscles, besides various evil conse- quences of these morbid conditions, may result from this cause when in prolonged operation. If combined Avith some of the other disturbing influences noticed in this section, it is a still more ready and common cause of mischief. Some organs suffer more particularly from a seden- tary mode of life; for example, the liver, in consequence of the increased task of decarbonization of the blood, which deficient respiratory exer- cise throws on it:1 the brain, from its direct and free communication with the centre of the circulation, which exposes it to an accumulation of blood when the distant circulation fails: hence bilious disorders, dyspepsia, hemorrhoids, headache, and giddiness, &c. Q6. (5.) Excessive mental emotion or exertion, and acute sensation, are common causes of disease. Closely knit together as the mind and body are, it is not surprising that they should ever be ready to affect each other, and that Avhen the bodily impression is strong, the mental affection should be found to be not slight nor transient. The heart suffers most remarkably in this way. Thus a sudden shock, whether of grief, surprise, fear, or even joy, may cause fainting, (partial sus- pension of the action of the heart:) nay, even death has ensued; and the expressions "frightened to death," and "killed with joy," are not always mere figures of speech. Sudden acute pain often causes faint- ing. Palpitation and irregular action of the heart are very common effects of emotion. The pallor of the face, and coldness of the extre- mities and surface, that result from strong mental disturbance are in- dications of the manner in Avhich the circulation is deranged under such influences, and these are almost always attended with a corresponding amount of internal congestions, leading to disturbance of the functions 1 AVhen there is more hydro-carbonaceous matter in the blood than can be burned off through the lungs, it is saponified by the liver, and thrown out as bile through the intes- tines, although iu normal states the bile itself is burned away by the respiration. 68 EXCITING CAUSES OF DISEASE. of various organs, manifested in spasms, hemorrhages, fluxes, and other like affections. Other organs also suffer under strong moral impressions. Spasmo- dic asthma, and spasmodic affections of the throat and stomach, are sometimes thus induced. Apoplexy, palsy, inflammation of the brain, chorea, epilepsy, catalepsy, and insanity, have been caused by exces- sive anger, terror, surprise, and joy. Mental emotions commonly affect the secreting organs, and especially influence the functions of the alimentary canal. A piece of very bad news takes away appetite, or impairs digestion. Fright or anxiety often loosens the bowels, or brings on a bilious attack, or jaundice. The uterine periodic function is remarkably subject to the influence of moral emotions, and many of its disorders may often be traced to this source. The secretion of the breasts is well known to be easily affected by emotion; it is increased by the pleasurable feeling of maternal fond- ness, and diminished by anxiety, distress, or even joyous excitement, and rendered depraved, so that it disagrees with the infant when the mother is suddenly shocked. There have been cases in which under such circumstances the milk has seemed to act even as a positive poison to the child. The less vivid emotions of the mind, and over-exertion of its faculties, are also sometimes exciting causes of disease. Long-continued depres- sion or anxiety often induces dyspepsia, costiveness, or diarrhoea, asth- ma, and functional disorders of the heart, liver, and kidney, monorrha- gia, and dysmenorrhoea; and structural diseases of the same parts oc- casionally follow these functional affections. In a large proportion of the cases of degenerative disease of the kidneys and heart that have fallen under my notice, the most obvious exciting cause of the mischief has been extreme anxiety, or long-continued mental exertion. There is generally an outward sign of the change manifested in the arcus or circulus senilis of the eye; this almost always indicates premature age brought on by the wear and tear of excessive mental anxiety or labour, or by "fast living." The influence of mental anxiety and exertion on the function of nutrition is proverbially illustrated by the expression "worn to a shadow;" and the decaying process may be observed in the large amount of urea, lithates, phosphates, and other results of animal decomposition contained in the urine under these circumstances, actually constituting a form of diabetes ureosus, or azoturia. Over- exertion of the faculties, or excitement of the passions of the mind, tells chiefly on the mind and the nervous system. In this way often arise congestions of the brain and exhaustion of nervous power, giddiness, stupor, headache, dull and disordered sensation, and even apoplexy and palsy. Or the disorder may be inflammatory, with symptoms of irregular excitement, nervousness, delirium, tremor, convulsion, partial paralysis, &c. Sometimes the effects of excessive mental exertion or moral emotion are only apparent in mental phenomena, the powers of the mind being so injured or disordered that various forms of in- sanity are produced. When we consider the variety and amount of employment and excitement (food and condiment, so to speak) that pass into the minds of persons in the busy and worrying scenes of MENTAL EXERTION—EXCESSIVE EVACUATION. 69 civilized life, it is not extraordinary that its functions, as well as the digestion, or any other vital action, should occasionally get deranged. 67. (6.) Excessive evacuation or loss either of blood or of some se- cretion, has been already noticed (§ 28) as one of the causes of debility, which then predisposes to disease; but if the loss be great or sudden, it may produce immediate disease itself. A certain fulness of the heart and blood-vessels is required for their healthy action, as well as for the support of all the organs which they supply. If a moderate quantity of blood be suddenly withdrawn, or a large quantity less sud- denly, the heart's action is impaired, rendered irregular, and perhaps interrupted, and the brain not receiving a sufficient current for the maintenance of its functions, fainting may follow, with loss of con- sciousness, accompanied, or succeeded, by palpitation, delirium, comrul- sion, or even death. The sudden impression in these cases is more marked on the brain than on the heart; for the same effects may be induced by the loss of a much smaller quantity of blood in an erect or sitting, than in a horizontal posture. Similar results have been found to ensue in consequence of the sudden removal of pressure from the vessels in any considerable part of the body, as by the discharge of the fluid of ascites, or by enclosing a limb in an exhausting tube. (Dr. Arnott.) Lower mentions a case of extensive varix (enlargement) of the veins of the lower extremities, in which the patient could not stand without fainting, until the legs were bandaged. In these cases, much of the blood, although not removed from the system, gravitates into the enlarged vessels, and becomes unavailable for the general cir- culation. The fainting which occurs is called cerebral syncope, because the functions of the brain are suspended; consciousness is lost before the heart's action is interrupted; but the disorder of the brain reacts on the heart, and thus adds another cause of impairment of its own action. This is Dr. Alison's explanation. On the other hand, if the hemorrhage is gradual, and the posture horizontal, other functions fail before the consciousness is lost—the chief symptoms being "feebleness of muscular action, paleness and collapse of the countenance, coldness, beginning at the extremities, cold sweat, commencing on the face, the pulse imperceptible," and the heart's action failing. The true nature of these effects, and of the reaction and nervous symptoms by which they are often followed, will be considered hereafter in connexion with the subject of anaemia. Not only blood-letting and hemorrhages, but other evacuations, such as purging, sweating, vomiting, and excessive catamenial and seminal discharges, are capable of producing syncope and general debility. The depression and faintness induced by these, although less prompt, are often more permanent than are those from blood-letting; for such evacuations imply, not only reduction in the mass of blood, but also exhaustion of the vital energies of the secretions and actions concerned in producing them. The diseases gradually induced by these several causes of evacuation are seldom of a simple kind. General weakness of the muscles and functions is a common result; but this is often complicated with symp- 70 EXCITING CAUSES OF DISEASE. toms of partial reaction, palpitation, spasms, noises in the head, spec- tral images, pains in different parts, sometimes very acute, but seldom long fixed, partial paralysis, and a defective and disordered state of the excretions. 08. (7.) Deficient evacuation of excrementitious matter, whether ha- bitual or accidental, is a very fertile source of disease. Its morbific influence is however considerably diversified. Sometimes it causes dis- ease by the positively noxious influence of matter retained in the sys- tem; this is the case Avhen it is the excretion of urine and feces that is concerned; at other times, by promoting fulness of the vessels, and thus leading to the various disorders commonly consequent upon this. To the latter category belongs the sudden suppression of hemorrhages, or other discharges which have become habitual, whether they be milk, mucus, serum or pus. Deficient excretion from the bowels is a very frequent cause of derangement in the health, manifesting itself by an entire train of symptoms, such as furred tongue, foul breath, depraved appetite, headache, general torpor and Aveakness, loaded urine, offensive perspiration and eruptions on the skin. The matter of alvine and renal excretions is essentially pernicious, and cannot be long retained even in their natural repositories without causing mischief. Feculent matter, when it has reached the large in- testine, is still acted on by the absorbents, which take up its more fluid parts, and with them, if long retained, fetid matter, which ought to be excreted. The solid residue becomes hard and scybalous, and may re- main lodged in the cells of the colon, a cause of irritation, distention, and obstruction (§ 51.) Sometimes the system then suffers before the intestine itself; but sooner or later this part becomes irritated, colic, diarrhoea, and inflammation ensue; and in some instances, where effi- cient remedies are neglected, even ulceration and other structural changes take place, before the offending matter is dislodged. The retention of urine has yet more serious effects. Besides me- chanical distention, irritation, inflammation, and rupture of the blad- der, which may follow from the constantly accumulating secretion (§ 51,) the fluid is partially reabsorbed, giving a urinous smell to the breath and perspiration, and sometimes causing typhoid symptoms, and in extreme cases proving fatal, Avith the presence of delirium, or coiiATulsions, and coma: effusions of serum, containing urea, are then found in the brain, chest, and other parts. These effects are more commonly produced by suppression than by mere retention; but, in fact, suppression often follows retention: retained urine is prone to decom- position (§ 53;) highly irritating and offensive matters are formed in it, Avhich cause injury to the bladder, rapidly extending up the ureters to the kidneys, whose functions then become impaired or destroyed. In some cases of the early stage of the severest form of Bright's dis- ease, in which the urine was very scantily secreted and highly albumi- nous, I have seen typhoid symptoms of the Avorst character, accompanied by a breaking up and partial solution of the colouring matter of the blood, Avith the appearance of pus globules in it; in two instances there was effusion of a bloody purulent fluid into the joints a day or tAvo be- DEFICIENT EVACUATION. 71 fore death: these results will be further noticed when treating of de- fective excretion and purification of the blood as an element of disease. Checked perspiration is a frequent and fully admitted cause of disease, commonly of a febrile, rheumatic or inflammatory nature: the sudden suppression of a fetid sweat in the feet, axillae, and other parts, has sometimes been followed by such serious disturbance of the health, as plainly to indicate that the matter thus retained must be of a highly noxious kind. The above illustrations relate to extreme cases; but the attentive observer will find that the same causes, insufficient secretion, and in- sufficient evacuation of excrementitious matters, in slighter degrees, are among the commonest sources of disorder; and it is by effecting a restoration of the proper state of these functions, that the almost uni- versal domestic remedies, as well as the common pills and draughts of the surgery, prove efficacious in preventing as Avell as in removing dis- ease. Many occasions will occur for the illustration of these facts. Numberless maladies arise from suppression or irregularity of the catamenial discharge, which appears to be blood in a highly carbonized state; it is hence manifest why its excretion gives relief. Diseases are not unfrequently excited, or rendered active, at the period of its total cessation. Something of the same kind may be said of the secretion of milk. The disorders which are thus produced are at first connected with local or general plethora; but eventually the quality of the blood becomes depraved in consequence of the accumulation of these excre- mentitious matters. 69. An artificial discharge or diseased secretion, such as proceeds from a seton or issue, or from an ulcer or diseased membrane, or an unnaturally profuse flow of an ordinary secretion—such as looseness of the bowels, if so long established as to have become habitual—cannot be suddenly suppressed without great risk of exciting disease. In the case of habitual puriform or sanious discharges from setons, issues, and old sores, sudden suppression has sometimes given rise to the most for- midable symptoms, showing plainly that a noxious matter had been throAvn back upon the system: the fear of the occurrence of such ac- cidental suppression, which cannot be always prevented, deters me from frequently employing these artificial drains in the treatment of dis- ease.1 Habitual hemorrhages, as from the nose or rectum, and the practice of periodical blood-letting, cannot be abruptly stopped with safety. The maladies Avhich are likely to ensue vary according to the 1 A patient who had been under my care with organic disease of the heart (hypertro- phy and mitral valve lesion) was recommended by another physician to have a seton inserted in the left side. Some months subsequently I was summoned to him in conse- quence of his having a severe attack of pleuro-pneumonia, of the right side, which su- pervened upon a sudden and altogether unaccountable cessation of the discharge from the seton. The affection proved intractable, being accompanied by an unusual degree of constitutional irritation and depression, and terminated fatally. Collections of pus were found in the right lung, and between layers of lymph effused on the pleura. A gentleman with chronic phthisis was in the habit of using croton oil freely as a counter- irritant upon his chest. Trusting in an imaginary security from this, he upon one occa- sion exposed himself to cold whilst a full pustular eruption was present upon his skin. The next night he was attacked with rigours, followed by fever and orthopncea, and sank in three days under suppurative bronchitis. 72 EXCITING CAUSES OF DISEASE. predisposition; but generally they are connected with local or general vascular fulness, or take the form of some disorder of secretion, or of the nervous system, directly depending upon disturbances in the cir- culation. Congestion of the brain, apoplexy, congestion of the liver, various hemorrhages and inflammations, gout, epilepsy, palsy, hysteria, hypochondriasis, and mania, may be specified by way of example. The suppression, or too rapid removal, of some cutaneous eruptions may be looked upon as belonging to this class. The diseases so ex- cited are sometimes inflammatory or profluvial, as gout, rheumatism, and diarrhoea; sometimes of a more nervous nature, as chorea, epi- lepsy, asthma, dyspepsia, and hysteria. 70. (8.) Defective cleanliness, ventilation, and drainage.—These influences might be expected to be very pernicious from what has been premised above; there are few kinds of filth more offensive, few mephitic gases more foul, and few descriptions of offal more abominable, than those that are excreted from the animal body itself. If, therefore, as we have seen, such matters are so very injurious, when not sufficiently eliminated out of the body, it is not surprising that they continue to be noxious, and may become active causes of disease even after they have been evacuated, if proper means be not taken to remove them out of the way. The need of self-purification might be inferred from the instinctive habits of many animals and birds, which take great pains to cleanse themselves and their young, and in many instances carefully remove excrements from their nests and habitations. Even plants are supposed by some botanists, to exhibit a like provision to preserve themselves against self-poisoning, by the constant spreading of their roots into fresh soil, that is not contaminated by their own ex- creted matter. Yet with strange disregard of these preservative in- stincts, and indolent neglect of the plainest dictates of reason, human beings continually expose themselves to the evil influence of their own accumulated filth, until disease is engendered, and aggravated into pestilence, and the usual rate of mortality among the people is doubled or tripled.1 Although the three particulars, neglect of cleanliness, imperfect ventilation, and defective drainage, operate much in the same way, and very commonly combine their influence, yet it will be useful to consider briefly the mode in which each excites disease, with a view to the consideration of remedial measures. 71. (a) Filth accumulated on the surface of the body, consists of the thickened residue of perspiration, mingled with such extraneous dust 1 Every practitioner of experience has to encounter manifold proofs of the potency of these causes in generating and aggravating disease; the profession and public possess a valuable collection of testimony on this point, in the following official reports:__ Report from the Poor Law Commissioners on the Sanitary Condition of the Labouring Classes. 1842. By E. Ghadwick, Esq. Supplementary Report of the Practice of Interment in Towns. 1843. By E. Chad- wick, Esq. Reports of Commissioners on the State of Large Towns and Populous Districts. 4 vols. 1844-1845. v Reports of Dr. Neil Arnott and Mr. Thomas Page on the Prevalence of Disease at Croy- don. 1853. . J DEFECTIVE VENTILATION. 73 or dirt as may chance to reach the skin. The sweat is peculiarly rank and offensive in some persons, especially when accumulated during much muscular exertion; and in some parts, such as the axillae, the perineeum, and between the toes, it is combined with an- odorous prin- ciple, whose disagreeable character would almost seem to have been intended by nature to suggest the necessity of frequent ablutions; yet how many, and these not confined to the lowest ranks, are "content to live in dirt and stink;" and often eventually pay the penalty of their filthiness in various cutaneous diseases thereby induced! The accu- mulation of filth on the skin also favours the propagation of vermin, and of contagious diseases, especially the itch, from which few of the "mighty unwashed" are totally free. The same influence also impedes free perspiration, and thus leads to the production of rheumatism and diseases of the urinary, and other organs, which sympathize with the skin. Neglect of cleanliness in clothes and dwellings, even when not immediately injurious through the direct contact of filth with the skin, may yet become hurtful by contaminating the air. 72. (b) Defective Ventilation, or insufficient change of the air of dwellings, might be considered to readily suggest its proper remedy by the feeling of suffocation that is induced; but it is not always the de- ficiency of oxygen, or excess of carbonic acid, that is equal to the pro- duction of a stifling sensation, which does most harm: it is rather the scanty supply of fresh air which stints the vital processes without sud- denly disturbing them; and the gradual accumulation of foul effluvia which slowly poisons without exciting alarm. Persons are gradually brought to endure, without distress, the impure air of a close room, although to anyone entering from the open atmosphere it may seem quite suffocating. Thus in the habitations of the poor, especially in densely populated towns, it is not rare to find ten or fifteen persons crowded to- gether in one small room, without any other supply of air than that which comes through chinks of the floor or window, or that which enters when the door is occasionally opened. Amongst the lower classes in. towns, the dread of cold prevails much more than the desire for fresh air; and except in the height of summer, the solitary window is rarely opened; and during the night, when the greatest number are collected together, every external opening is carefully closed. During the winter the same plan is pursued; but, if there be then any fire on the hearth, a greater amount of ventilation is perforce ensured. The habitual want of pure air especially exerts an unfavourable in- fluence on the state of the blood, and on the functions of circulation and nutrition, causing pallidity of the surface, and imperfect develop- ment of the corpuscles and plasma, which, then, instead of contributing to the nourishment of the textures, degenerate into scrofulous or tu- berculous matter, whose deposition in the internal organs or glands is further favoured by the weakness of the circulation. Exercise does, in some degree, counteract this effect of impure air: thus Dr. Guy found that in the close workshops of a printing establishment, 44 per cent. of the compositors, whose employment requires no exertion, fall victims to phthisis, while not more than 3H per cent, of the pressmen, who, 74 EXCITING CAUSES OF DISEASE. while breathing the same air, use active bodily efforts, do the same. This difference is quite intelligible when it is remembered that active exercise tends to remove congestions, and to promote excretion, by in- creasing and extending the force of the circulation, and to excite the respiratory function, so purifying the condition of the blood. Similar exercise in pure air has, however, much more salutary effect; for the deaths from phthisis among out door labourers do not exceed 25 per cent. Insufficient ventilation is by no means confined to the habitations of the poor. In modern days, Avhen the construction of houses is more complete than it was in olden times, there are no longer the latticed casements, chinky floors, ill-fitted doors, and above all, the roaring pile of burning wood on the spacious hearth, that supplied abundant venti- lation to the houses of our forefathers: now, in proportion as houses are "well built," every crevice is so thoroughly stopped, that our rooms -are well nigh air-tight, and when doors and Avindows are closed, the occupants are consequently enclosed in an atmosphere, which is more injurious in proportion to the number assembled. Add to this the vi- tiating effect of artificial lights, and fires, whose smoke does not per- fectly escape for Avant of sufficient draught, and it will be very ap- parent why it is that modern houses often comprise conditions eminently calculated to ensure the presence of this cause of disease. In public offices, schools, hospitals, churches, chapels, theatres, and other places where great numbers collect together, the mischief is still more fully in operation; and it is quite certain that not only is the public health much injured in this way, but that much of the useful or agreeable ob- jects of such assemblies is also lost in consequence of the discomfort caused. The ill effects of deficient ventilation are increased by heat and mois- ture ; the former operates, not only by increasing the animal exhalations, but also by rarefying the air, and thus reducing the amount of oxygen in any given bulk; moisture probably acts by lessening the difference be- tAA'een the air respired, and that contained in the lungs, Avhich promotes that diffusion, or interpenetration of gases whereby the access of oxygen to the air cells is ensured. For be it remembered, the air taken in at each inspiration, is not enough to reach far in the pulmonary tubes; its further transfer into the air-cells is mainly accomplished by the law of diffusion of gases, which operates poAverfully in proportion to the dissimilarity between the gases. Gases or vapours of a positively noxious quality are engendered, during certain occupations, which augment the evils of deficient venti- lation. Such is the case in many chemical works, slaughter-houses, and dissecting-rooms, soap, glue, and catgut manufactories, and in em- ployments in which materials are used containing mercury, white lead, and arsenic (§ 53.) The deleterious operation of effluvia arising under these circumstances may stop short of a directly poisonous effect, and yet by adding to the unwholesomeness of the atmosphere, it may gra- dually undermine the health: it is best counteracted by more efficient A7entilation. 73. (c) Defective drainage necessarily produces an active state of DEFECTIVE DRAINAGE. 75 the influences above specified, namely, filth and foul air; but it also implies circumstances that may exceed these in pernicious operation. The soil, Avhich drains from habitations, contains in addition to excre- ment, dirty water, the washings and remnants of animal and vegetable matters used as food, and other offal; all these are mixed together and stagnant in the corrupting slough that is retained in cesspools and privies, or that is carried into seAvers. The stench Avhich exhales when these receptacles are opened, gives some idea of the deleterious influence they originate, and the fearfully poisonous nature of the emitted gases is often proved by the sudden faintness and sickness, nausea, vomiting, and diarrhoea, which attack persons engaged in emptying them. In- stances have occurred of individuals being speedily asphyxiated by the gases of cesspools; and others are on record in which, although the re- sult was not immediately fatal, congestive or typhoid pneumonia en- sued, which passed into gangrene in the first stage. (Chomel.) The precise nature of the gases evolved in these circumstances has not been fully ascertained; but they obviously contain much sulphuretted and carburetted hydrogen; these, however, although known to be highly noxious, do not comprise the most dangerous ingredients of these of- fensive effluvia. It is no wonder then, that every ill-drained house has a Pandora's box, ready to pour forth its evils whenever occasion offers; and always oozing them out in degrees sufficient for the impairment of the health of the inhabitants, and the gradual excitement of cachec- tic and other chronic diseases. Hence it is, as appears in the several sanitary reports before cited, that the mortality rises in a remarkable proportion in all those districts of towns where sewerage is absent or inefficient. The worst nuisance of this description is the cesspool with- out a drain from it; unemptied for months or years, and often imper- fectly covered, it continually poisons both air and water; and typhoid fever, diarrhoea, cholera, dysentery, dyspepsia, inappetency, general weakness, and malnutrition are the results of its pestiferous operation acting in different degrees. Scarcely less injurious, and even more in- sidious in its operation, because the effluvium is less offensive, is the untrapped drain often found in connexion with the sewers of large towns. This cause of disease exists extensively in London, not only in the street drains, which are always open and emitting the gases of the seAver, the bad odour of which is perceptible during certain winds, but also in the drains of houses Avhich are either intentionally or neg- ligently left open, or are not kept air-tight by the presence of water in the traps. Nothing is more common than to perceive the peculiar smell of the drain on entering a house, and in many instances I have found that this has proceeded from the trap being left open, or from the water being dried aAvay, the trap being therefore inoperative, al- though requiring only the simplest expedient to remedy the evil. When a single trap is open in a house, especially in the Avinter Avhen doors and AvindoAvs are closed, and the supply of fresh air is inadequate for the fires in the house, the foul air is draAvn up from the sewer in a strong current, and quickly pervades the house from bottom to top, carrying everyAvhere its pernicious influence. It its surprising how ignorant servants and their employers, and even professional men, seem 76 EXCITING CAUSES OF DISEASE. to be on this point, although one which so immediately concerns their health and comfort: I have visited in many houses where illness, or impeded convalescence, low nervous fevers, boAvel complaints, influenza, neuralgia, and headaches, besides other ailments, haAre been induced by this cause. In some instances the leakage is a consequence of the inroads of rats, or the displacement of the brickwork of the drains. It may be useful to state, that besides by the smell, which is not ob- vious to every one, the effluvia of drains may be detected by the darkening of white paint, and the speedy spoiling of meat kept in the basement story of the house. 74.% (9.) Of all the exciting causes of disease, there are none more common than extremes or sudden transitions of temperature. Both heat and cold, however, operate on the living body in different modes, and cause disease in a variety of ways. Extreme heat and extreme cold are directly destructive to life. Heat above 180° coagulates the albumen of the blood, and thus ob- structs the blood-vessels, and produces other chemical changes of a dis- organizing nature (§ 53:) a part that has been raised to this tempera- ture, therefore, necessarily dies; it cannot live again. It is true that we occasionally see the application of boiling water at 212°, of boiling oil at 600°, and of red hot iron at 1000°, produce no other effect than violent inflammation and blistering of a part; but that is because these bodies have then been applied for too short a time to do more than violently stimulate the part; time enough is not afforded to raise the part to the decomposing temperature; an instant more, and the part would be killed. Cold below 32° freezes the water of the fluids; and as it destroys the life of tender plants, so also it often kills parts of animals; but whether by the expansion of the ice injuring the delicate organization, (Sir B. Brodie,) or whether from the mere stoppage of the circulation, or from some other cause, is unknown. The destroyed part may be afterwards separated from the living parts by the processes of inflam- mation and sloughing. From the observations of Dr. James Arnott, it appears, however, that parts of the surface and of limbs may be con- gealed by the application of a freezing mixture, without any permanent injury to the structure; and he strongly recommends this method of benumbing the part to prevent the pain of surgical operations, as safer than the induction of general insensibility by the inhalation of chloro- form. Probably the duration and degree of this artificial congelation fall short of the more serious effects of frost bite. The method deserves a fuller trial not only for surgical purposes, but also for the sake of its therapeutical influence in the removal of pain and the subduction of inflammation. The power of the body to resist cold, whether generally or locally applied, is apparently connected with the strength of the circulation. When this is vigorous or under the influence of excite- ment, there may be little or no general chill, and the parts exposed to cold may not suffer even in intense degree of cold. On the other hand, where the circulation is weak and the vital powers low, a moderate de- gree of cold may take serious effect. In many instances the sick and EFFECTS OF HEAT AND COLD. 77 worn-out soldiers in the Crimea, suffered loss of limbs from frost-bite from two hours' exposure to a cold little below the freezing-point. 75. A disorganizing degree of heat, if extensively applied, as in severe burns and scalds, acts like a violent mechanical injury—such as tearing off or crushing a limb (§ 52.) It directly depresses all the functions: the pulse becomes very weak, frequent, and sometimes irre- gular; the muscular strength is almost annihilated, and consciousness is nearly or quite suspended. In this state, notwithstanding the sti- mulant power of heat, and the inflammation which it generally excites, patients require stimulants, and they often die in a state of complete collapse, without any rallying or reaction. Extreme cold, also, if ap- plied for some time to the whole body, depresses and paralyzes.all its powers, even that of generating heat, and, therefore, of resisting cold. Sir Astley Cooper observed, that on plunging kittens into ice-cold water, the arterial blood did not become venous in the veins; and Chossat found, that when animals were killed by cold, there was arterial blood in the left cavities of the heart. The limbs become benumbed by ex- treme or continued cold: and hence persons are drowned in cold weather much more speedily than in Avarm. In degrees of cold, on the other hand, not sufficiently intense to destroy the vital processes, more oxygen is absorbed by the blood, more carbonic acid formed, and more heat generated, these being the means whereby animals are enabled to resist cold. As, however, extreme degrees of cold reduce the vital properties and functions of the body, so it is reasonable to infer that the prolonged application of more moderate cold must also impair them; and this inference is confirmed by the fact that when the body is be- numbed by continued cold, the circulation is enfeebled, and the secre- tions more or less disturbed. 76. Heat, in insufficient intensity to effect the decomposition of or- ganized structure, is directly stimulant. It excites the functions of organs, and when generally applied, may even induce a state of fever. Thus when a person is in a vapour bath, or a hot-air bath, the pulse is quickened, and the whole surface becomes red, full, and hot; there are throbbing and pain in the temples, and a feeling of feverish op- pression, until a sweat breaks out; this then soon relieves the superficial tension and fulness, and reduces the increased heat. Effects of this kind often ensue from confinement in overheated rooms: and if there be any tendency to local congestion or inflammation, particularly in the head, the excitement may be enough for the production of mischief. The continued operation of heat enervates, reduces the strength and appetite, and may excite disorder of the liver. Liebig thinks that the oppressed breathing, so often felt in heated rooms, may be ascribed to the smaller amount of oxygen which air rarefied by heat contains; but it is probable that this is not the only cause. The exposure of a portion of the body to heat, may produce still more disordering effects, if the part overheated be of a nature disposing it to suffer from the excitement. Thus solar or artificial heat, applied to the head, may cause severe headache, apoplexy, or inflammation of the brain. Heat to the spine, as from sitting with the back near a large fire, is very apt to cause sickness and faintness, and, if continued, 78 EXCITING CAUSES OF DISEASE. may induce convulsions. More local inflammations, as of the eye, ear, and portions of the skin, are frequently caused by exposure of the suf- fering parts to heat. Gout may sometimes be excited in the feet by the application of the same stimulus; this is often done with the design of localizing the disorder. 77. Cold, on the other hand, is directly sedative. It contracts tis- sues and vessels, especially the arteries, and thus at first renders parts pale and shrunk. In persons of feeble circulation, the fingers are sometimes quite bloodless and numb after bathing; the cold having quite closed up the arteries.1 But cold also retards the passage of the blood through the capillaries; the viscidity of the liquor sanguinis seems to be increased by it; the corpuscles stick to the sides of the vessels, or move but slowly, and the part soon becomes purple or blue from con- gestion of blood. This purple colour is chiefly seen in parts much ex- posed, and where the blood habitually enters with freedom, as for instance the cheeks, ears, nose, and hands. There is also much in- ternal congestion from the intropulsive operation of the cold—that is, the external parts being constricted and obstructed, blood accumulates more in internal parts, and the heart's force is mainly expended on these. This may in part account for the degree of stupor and ultimate insensibility into which persons exposed to extreme cold are apt to fall. In some such cases there has been a flow of blood from the nostrils or ears: the stupor has continued for hours after the heat and circulation have been restored; and in fatal cases, much serous effusion has been found in the brain.2 Further observation is needed on these points; but it is most probable that these changes are not the mere result of the congestive influence of cold. In proportion as the blood remains long stagnant other functions are also interrupted, nutrition and se- cretion in particular; and the arrest of these causes a more serious re- sult than what would follow from the mere occurrence of a temporary congestion. We shall hereafter find reason to conclude that the lower- ing of the chemical changes in the blood and tissues from the operation of cold, in itself contributes to increase the capillary congestion. 78. Hitherto we have considered the immediate operation of cold (§ 74, 77.) But its indirect effects are more commonly known: these are, reaction, irritation, inflammation, and their consequences; they are more manifest where the cold has been partially applied, and the strength of the general circulation is not reduced. Thus, after a part has been exposed to severe cold, it becomes the seat of increased flow of blood, so soon as it is restored to warmth, this causes redness, pain, and more heat; and various forms of inflammation may ensue, generally, however, modified by the specific effect which the previous cold has ex- 1 A similar effect may be watched through the microscope, on applying ice-cold water to the frog's web: the arteries contract to obliteration. This is contrary to the asser- tion of PoiseuiUe. (See my Gulstonian Lectures, Med. Gaz., July 16, 1841, p. 639.) It must be remarked, that the primary action of cold on the arteries is strictly stimulant, exciting their vital property of contraction; but its direct operation on textures and or- gans is sedative, because it impedes the circulation which supports their functions. So, too, it has been found, that when its influence reaches the heart, it paralyzes its powers (2 74-) 2 Kellie, Edinburgh Med. Journal, vol. i., p. 304. MORBIFIC OPERATION OF COLD. 79 ercised on the vessels and nerves; and also varying with the strength of the general circulation. Thus, chilblain, gangrenous or erysipela- tous inflammation, paralysis, and altered sensation are among the in- direct effects of cold. As much of the disorder arises in these cases from the violence of the reaction and inflammation, and as this depends on the sudden return of heat and circulation in the part, it becomes an obvious measure of prudence in the treatment of frost-bitten limbs, to retard such return by cold applications. But as Dr. Alison well re- marks, this precaution is not needed, where the sedative effects of cold have been more general; here warmth and stimulants may be used freely, for there is no fear of an injurious partial reaction. 79. We have hitherto been considering the manner in Avhich cold causes disorder in the parts to Avhich it is applied; but this is not the most general way in which cold excites disease. A person gets his feet wet, stands in a draught of cold air, or, is exposed to cold when insufficiently clothed; he afterwards becomes diseased—not in the feet, or the parts chilled, but in some internal part. He gets a sore throat, a "cold in the head" or chest, an inflammation of the lungs, a rheu- matism in the limbs, a looseness of the boAvels, a catarrh of the bladder, or any other disease to which he may be predisposed (§ 14.) Now how does the external application of cold cause this internal disease? How is the effect transferred from external to internal parts? Dr. Alison supposes that the cold operates chiefly on the nerves, and that the sensation Avhich it excites is conveyed by the nerves to the in- ternal organs, where its morbid effects become manifest. But it must be objected to this that the morbific effects of cold are by no means proportioned to the sensation, or nervous impression, which it excites. A person may have his limbs aching and benumbed with general cold; and yet no internal disease results. But if he has been exerting him- self, is perspiring, and then gets his feet wet, or is otherwise chilled, and does not continue his exercise, he will be pretty sure to catch cold, and to exhibit some one or other of its internal morbid effects, even although he has scarcely been sensible of any impression. It therefore seems more probable, that external cold excites internal disease, by ; deranging the circulation and condition of the blood, particularly in the capillaries. Cold checks the secretion of the external surface, per- spiration ; it constricts and obstructs the vessels of the skin (§ 77,) and thus throAATs more blood inwardly, so that internal congestions are pro- duced—these internal congestions impair the functions of the affected organs, especially if they are such as are concerned in excretion (§ 68,) and in other Avays lay the foundation of disease. This intropulsive j effect of cold takes place more readily and to a greater extent, in pro- j portion to the weakness or sluggishness of the capillary circulation. If ' this be weak naturally (§ 20,) there is a constant liability to "take cold." Or if it be weak and relaxed from previous excitement, during j fatigue (§ 23, 24,) or during sleep, the same result is apt to follow. : Hence persons are most liable to catch cold after being in a hot room, after making exertion, or Avhen asleep. On the other hand, the inju- rious effect of cold is lessened, or prevented, by a vigorous state of the capillary circulation, whether that vigour be natural, or artificially ex- 80 EXCITING CAUSES OF DISEASE. cited by continued exertion, stimulating drinks, or by febrile excite- ment (§ 17.) On this view we can understand why the partial, but continued, ap- plication of cold, such as occurs from draughts of cold air, wearing damp clothes, and standing on cold stones, should be particularly inju- rious, even although the sensation of cold excited is not great. Such chilling influences acting long on the same part, completely constrict its vessels, check its secretion and nutrition, injure the balance of the circulation, and by determining a corresponding amount of congestion inwardly, fix it in some part predisposed to disease (§ 14.) Nor is it to be overlooked that this derangement of circulation and of secretion and nutrition produces a corresponding change in the condition of the blood; and this change serves to explain why the morbific influence of cold often cannot be removed until some critical discharge takes place, as by perspiration or urine. It is probably by interrupting or modifying the processes of nutrition and disintegration of textures that cold ope- rates in causing rheumatic pains in muscles and fasciae exposed to its influence. Thus the decaying material which under ordinary warmth assumes the form of urea, may by the retarding influence of cold be changed only into lithic or lactic acid, and immediately exert that irritating influence on the part which causes the rheumatic pain result- ing directly from cold. When a person has thus taken cold, which he knows by general sensations of coldness and weak circulation, rather than by any feel- ings in the part chilled, powerful measures which tend to restore the balance of the circulation and excite the defective secretion, such as violent exertion, a hot or vapour bath, or stimulant drinks, will often prevent the further progress of disease. The general exposure to a cold atmosphere, if not long continued, is less injurious than a partial application, both because it disturbs the balance of the circulation less, and because also it supplies the lungs with denser air, and therefore with more oxygen; its impression on the nerves of the face and chest also excites more energetic respiratory movements, which maintain the heat and the vigour of the circulation. Healthy persons rarely take cold when travelling on the top of a coach, or in a perfectly open car- riage, but they frequently suffer if in a close carriage with the windows open. Railway travelling is particularly dangerous in cold weather, on ac- count of the strong current of air caused by the speed. It was not discovered, until abundantly illustrated by numberless cases of catarrh, lumbago, and pleurisy, that more clothing is required even in first-class railway carriages, than in stage coaches, and that there is rarely any need of an open Avindow to secure ventilation. Damp foggy air seems to act injuriously on the body in a peculiar manner, independently of its mere temperature, irritating in particu- lar the eyes and air passages. Professor Schoenbein considers this effect to be due to the presence of ozone, a principle which he con- ceives to have the power of producing influenza and catarrh, at the same time that it is capable of destroying malarious and infectious poisons. RESISTANCE TO COLD. 81 80. Susceptibility to the morbid effects of cold is to be diminished by means tending to invigorate the capillary circulation, especially when they are such at the same time as serve to promote that process of reaction which is nature's ordinary method of resisting cold. Now nothing does this more than sudden artificial applications of cold, as by cold bathing or sponging, followed by friction, exercise, heat, or stimulant applications, which promote the reaction (§ 16.) The great art in accomplishing these intentions, consists in using the cold in such a manner and degree, and in having the body in such a state before and after the application, that the reaction or glow shall be most fully produced. If the cold be applied too long, or when the body is ex- hausted by fatigue or exertion, or when it is naturally too weak, the depressing effects of the agent Avill be continued, there will be little or no reaction, and sensations of languor and chilliness will show that the application has been injurious instead of beneficial. The addition of salt to the water of baths communicates a stimulant property, which promotes reaction, and a similar influence results from the force or shock with Avhich the water is applied. The shock excites frequent deep and forcible respirations through the influence of the nerves; and these accelerated breathings are probably the efficient cause of the process of reaction which follows. The reaction which folloAA-s the judicious use of cold as a therapeutic agent, may prove serviceable, not only in resisting the further influ- ence of cold, but also by removing congestions and irregularities in the circulation produced by other causes, and by exciting in the capillaries and secernents new actions, Avhich may supersede those of disease. It is thus that the "water cure" of Priessnitz chiefly operates; and although too powerful an agent to be intrusted to unskilled and un- scientific hands, it promises to become a valuable addition to the means of combating diseases, particularly of a chronic kind. The ex- citement and exhilaration sometimes produced by the free application and imbibition of cold water is very remarkable, and in numerous dis- orders connected with mere loss of tone in the vascular system, may prove very beneficial. But in cases of organic disease, or extreme weakness, the influence of cold water may be very injurious, even though it may seem refreshing and invigorating for the time. I have known many cases in which patients have fancied themselves im- proving under the treatment, Avhen in fact organic mischief has been rapidly increasing, and flesh and blood have been wasting. The ex- citement induced by the water almost resembles intoxication, giving a fictitious feeling of strength, in the midst of increasing weakness. 81. In the preceding remarks on cold, it must be understood that the term is applied relatively, not absolutely: cold is not a fixed tem- perature, or range of temperature; but simply a degree of heat con- siderably below the temperature of the body. Thus a living body that has been warmed throughout to a heat of 98°, and kept in an excited state by that temperature, would suffer from a draught of air at 70°, which Avould then feel cold to the body, and produce the physiological and pathological effects of cold. But if the body had not been pre- viously warmed, so that the temperature of most parts of the surface 6 82 EXCITING CAUSES OF DISEASE. exceeded 85°, or if, being so warmed, the energies of the body had not been exhausted, then air at 70° would feel pleasant, and produce no chill. This is one of many conditions which distinguish vital from physical properties. Physical or chemical properties are invariably affected in a certain Avay by given temperatures, independent of pre- vious circumstances: but vital properties are variously affected by them in consequence of possessing that power of adaptation, whereby they are enabled to maintain the same states of function in varying external circumstances. It is for these reasons that atmospheric changes in variable climates are fertile causes of disease. In this country on a sudden change of wind, the temperature often falls 15° or 20° in the course of a day, and without any particular exposure the body may become so chilled in consequence as to suffer to a degree sufficient for the production of disease. Internal congestions commonly result, but the seat of the congestion varies with the state of predisposition. After the heat of summer, the organs most apt to suffer are the liver and the abdominal viscera, because they have then been exposed to great excitement (§ 25:) on the other hand, in the spring, after the winter cold, the lungs and air-passages are more prone to derangement (§ 26.) II. NON-COGNIZABLE AGENTS. We now proceed to notice those causes of disease, whose existence is merely inferred from the fact that disease prevails under certain circumstances, and cannot be explained unless upon the assumption of the existence of certain peculiar agencies, although we cannot prove their existence in any other way (§ 51.) These comprise what are termed the endemic, epidemic, and infectious poisons. In the reports of the Registrar General these poisons are termed zymotic (£1^, a fer- ment:) the epithet implies an hypothetical explanation, which may perhaps be still deemed open to question; but it is, nevertheless, a very convenient designation for these mysterious morbific influences. (1.) ENDEMIC POISONS. ^ 82. Persons living in a marshy district are frequently afflicted by a disease called ague, which does not attack people inhabiting dry lands. And again, the inhabitants of certain deep valleys are often affected with the swelling in the neck, called bronchocele or goitre; while the neighbouring mountaineers are not so affected; and when the inhabi- tants of the valleys remoA'e their residence to the mountains, they generally lose their liability to the disease. These affections are in- stances of diseases which may be said to dwell among the residents in particular spots; hence they are called endemic, in the people \tv fi^oj.) Much doubt still exists regarding the precise source of endemic in- fluence ; some persons suppose that it is to be traced to the water, others to emanations from the soil. Intermittent and remittent fevers cer- tainly very commonly originate in marshes, jungles, and rice-grounds, for it has been found that when the wind blows across such tracts of land, the disease appears in persons residing to leeward, but not in ENDEMIC POISONS. 83 those residing to windward; and it has been abundantly proved, that when the marshy spots are drained, ague ceases. From these and similar facts, it has been inferred that the cause of ague is an efflu- vium, miasm, malaria, or bad air; an aerial poison, inhaled with the breath, and absorbed from the lungs into the system. 83. The exact nature of marsh malaria has not hitherto been deter- mined. It has never been detected by chemical analysis. Professor Daniel conjectured that the malaria which causes the destructive en- demic fevers on the coast of Western Africa, might be sulphuretted hydrogen evolved from the sea water by the decomposing vegetable mat- ter brought down by the rivers: but experiments made in the late un- fortunate expedition to the Niger are opposed to this notion. The mi- croscope, rather than chemical analysis, will probably one day throw light on the nature of malaria. But although the exact nature of marsh malaria is not known, we are acquainted with some of its general properties. It seems to be heavier than air; for persons occupying a ground floor suffer from it more than those living in upper apartments. Water seems to absorb or destroy it; for persons on board ship, or on the side of a lake op- posite to the marsh, are not affected; although a favourable wind will convey the pernicious influence to a much greater distance over land. A damp state of the air, however, favours its production: good fires in a house afford marked protection to its inmates. It seems to be attracted by trees; for the vicinity of trees is doubly dangerous; whilst places beyond the trees are more free from its effects than others at the same distance which are unsheltered. 84. The chief points known, with regard to the source of malaria, are, that it arises from the operation of the sun's heat on marshy ground, or on the banks or deltas of rivers, especially if devoid of tidal flow, after evaporation has proceeded to some extent; putrefac- tion of organic matter not being an essential part of the process.1 The virulence of the malaria, shown in the severity of the disease excited, and in the number of persons who are affected, seems to bear some proportion to the heat, which has led to its development. Thus the ague of this country, the pernicious intermittent of Italy, and the ma- lignant intermittent of Western Africa and the West Indies, all seem to arise from similar endemic causes, but differ materially in their viru- lence, being the most formidable where the heat is greatest. A cer- tain amount of moisture is, however, requisite to the effect; a very dry season, which desiccates a marsh, stops the malaria; and the deposit of the evening dew always favours its production (§ 83.) Excess of moisture, on the other hand, checks its development, so that a very wet season, as well as a very dry one, may render a marsh less un- healthy (§ 83.) But extreme heat does not diminish malaria on the banks of rivers, because portions of these are never dry. The low shores of the Mediterranean and the Black Sea are always malarious at the commencement of hot weather, because in the absence of a tide 1 Chisholm and Ferguson, Ed. Med. and Surg. Journal, vol. vi.; Trans. Roy. Soc. Edin., vol. ix. 84 EXCITING CAUSES OF DISEASE. there is none of that frequent salt washing and drainage, which puri- fies other European shores. It is not only marshy, or low grounds, that engender malaria, al- though these are the situations that are most faA^ourable to its produc- tion. All that seems to be really requisite, is the continued operation of the sun's heat on moisture stagnant upon, or near, the surface of the ground. I know instances in Avhich ague has attacked persons living on a height of mountain limestone, forming a small table land below higher ground. Some swampy lands are not malarious; peat bogs, in particular, show a remarkable exemption from decomposition and effluvia of all kinds. It is a curious fact that malaria seems to be more active at night, than by day. Its power seems to be diminished by the cultivation and dense peopling of districts where it has prevailed. The Italians date its development in the deadly Maremma from the time that the coun- try Avas desolated by the Plague. This influence of the population is probably connected more with their activity than with their presence; for the ague disappears in proportion as the inhabitants drain the marshes and remove the source of the poison. 85. The morbid effects of marsh miasms are multiform: intermittent and remittent fevers of various types, are the most remarkable among these, and particularly affect the new residents in a marshy spot; but the older inhabitants suffer from diseases of the liver and spleen, ner- vous affections, rheumatism, dropsy, and cachectic complaints, and are generally short-lived. The first operation of the malarious poison seems to be on the quality and distribution of the blood: in the worst cases this liquid becomes speedily darker in colour, and otherwise al- tered, and accumulates to an extraordinary amount in the internal or- gans, where it then suffers still further in consequence of its stagna- tion and want of purification by the ordinary processes of excretion. The fit of an ague is the reaction (§ 16) of the vital powers against this cumulative influence of the poison on the blood: if the vital powers are strong, and the dose of the poison not overwhelming, the fit success- fully removes the internal congestions, and partially restores the purity of the blood through increased excretion; but some poison being still in the system, similar effects are again produced after a longer or shorter interval; and so alternate attacks of ague, and intermissions, appear in succession. One of the most remarkable characters in the diseases resulting from malaria, is the periodicity of their attacks, and the diminution or cessation of the symptoms in the interval. This is probably due to the alternate accumulation of the malarious influence in the body and the reaction of the vital powers against it. 86. There can be little doubt that there are other kinds of malaria besides those which cause intermittent and remittent fever (§ 80, 81.) Yellow fever and plague are endemic diseases, most probably arising from aerial poisons. The propagation and severity of the latter, and perhaps even its very existence, is to be mainly ascribed to the filth and impurities of the towns where it preATails. These, however, are EPIDEMIC POISONS. 85 cognizable causes, whose operation in exciting and predisposing to dis- ease, has been already noticed (§ 70—73, § 22.) Bronchocele and cretinism, and allied results of depraved nutrition, manifested in glandular enlargements, fibrinous and dropsical swellings of the cellular tissue, distorted limbs, stunted growth of the body, and imperfect development of the mind, are dependent on endemic causes; Avhich are most probably miasms arising from the low marshy grounds of the deep valleys of Savoy. Some other endemic diseases can also be traced to cognizable causes; the Guinea worm, seems to be due to drinking water containing its ova; the pellagra of Northern Italy, and the plica of Poland, are brought about by neglect of cleanliness, and unhealthy modes of living, and probably are both immediately dependent on the production and propagation of a parasitic vegetable on the roots of the hair and skin.1 (2.) EPIDEMIC POISONS. 87. There is another group of diseases, which resemble the endemic in affecting many persons in the same place and at the same time (§ 81.) But they differ in these respects, they do not regularly return at stated seasons (§ 84,) and they are not confined to particular localities (§ 82,) although they infest some more than others; they attack a whole dis- trict, a whole country—and sometimes almost a whole hemisphere— within a very short time; often coming on without obvious cause; pre- vailing for awhile, and then disappearing for an uncertain period; which may be for months, or years, or even for intervals too long to be remembered. These disorders are called epidemics, (irtt Stj/ioi,) be- cause they seem like a blight, or pernicious influence, blowing on the people; and therefore affecting a whole country at once. 88. The cause of these diseases is supposed to be something in the atmosphere; for the atmosphere is the only thing that is common to all the places to which the affection extends: but the nature of the epidemic poison is just as mysterious as the endemic. It is true that some diseases, which seem to preATail epidemically, may be traced to the cognizable qualities, cold, heat, dryness, and moisture of the air (§ 74, et seq.) Thus diseases excited by cold sometimes prevail, as epidemics, in the winter; those excited by heat, in the summer; catarrhs and rheumatisms abound in cold damp Aveather; croup and quinsy be- come common during the prevalence of a cold east wind in the spring; diarrhoea and dysentery are rife in the autumnal fruit season. Other disorders, again, such as dysenteries, fevers, and scundes, have in some instances obviously arisen from deficient or contaminated food, bad water, or some other distinctly cognizable cause (§ 60, 70, et seq.) But as these causes all belong to the class of cognizable agents already noticed (§ 52, et seq.,) they do not need to be adverted to here. 89. But there are diseases occurring epidemically which do not ap- pear to have any discoverable connexion with season or temperature. Thus an epidemic influenza may come on at any season of the year, and rapidly spread through a country, and then cease as unaccountably 1 Robin, Histoire Naturelle des A'dge'taux Parasites. 1853. 86 EXCITING CAUSES OF DISEASE. as it began, or it may break out simultaneously at distant parts where the temperatnre is exceedingly different.1 So, too, diseases that are obviously excited by other causes, whether infectious or otherwise— as, for instance, typhus and scarlet fevers, measles, small-pox, and erysipelas,—sometimes prevail so extensively, and with such peculiar characters, that some common influence besides the agencies that usually produce them, must be admitted to be concerned in their sudden ap- pearance and diffusion. The nature of this influence is unknown; but it is spoken of as epidemic (§ 87.) 90. Various diseases, fevers, inflammations, and many other kinds of ailments, at some periods assume a remarkable character in common, or type (as it is called;) for example, they may be attended with unusual Aveakness, or unusual excitement, or a tendency to hemorrhage. This is said to be due to an epidemic or prevailing diathesis, or constitution. Thus at uncertain times, fevers, wherever arising, and from whatever source, are always more Ioav, typhoid, or adynamic, than usual; exanthema- tous diseases then generally partake of the same character; and even patients affected with inflammations will not bear depletion as they . would at other times. Of late years this low type has prevailed more or less, and may be contrasted with that of a period of thirty years ago, when an inflammatory diathesis was as common, and blood-letting was then advantageously employed even in continued fever. 91. It has been before stated (§ 88,) that we are quite in the dark as to the nature of epidemic influences or causes of disease. Many conjectures have been advanced, some of them with much plausibility, although without any substantial support. Dr. Prout states that, shortly before and during the prevalence of the malignant cholera in this country, he noticed a slight but decided increase in the average weight of the atmosphere, as if from the addition of some ponderous gas. At the same time, he remarked an unusual acidity in the saliva even of healthy persons, and such an absence of lithic acid from the urine, that he was inclined to suppose the existence of a peculiar disposition to form oxalic acid, and to refer this to the same unknown cause which was active in the production of cholera (60.) He suggested the possi- bility that some such subtile deleterious agent, as seleniuretted hydro- gen, might be diffused through the atmosphere and produce the perni- cious results observed. Such an agent might be evolved from volcanoes, and it is a curious fact that several severe epidemics have been known to be preceded by volcanic eruptions. This has not however been found to be always, or even often, the case. Neither do volcanic countries suffer the first, or the most intensely from epidemics, as they ought to do, if this supposition were based on fact. Electro-magnetic influence, and abnormal production of ozone, are among the assumed causes of epidemic disorder, and the assumption has more of probability on its side, on account of the ubiquitous character of these agents. But here, again, there is no other evidence for the opinion to rest upon,' than a feAV equivocal observations regarding the occurrence of auroras 1 The influenza of 1836 prevailed simultaneously in London and Cape Town, although it was then the summer of one place and the winter of the other. See "Annals of In- fluenza," by Dr. Theophilus Thompson. 18-30. INFECTIOUS POISONS. 87 boreales, and disagreeably odorous fogs (said to contain ozone,) coinci- dently with certain epidemic invasions. 92. Many analogical arguments have been adduced in support of a favourite notion of Linnaeus, namely that epidemic diseases are caused by animalcule tribes. This hypothesis has been ably advocated by Sir H. Holland,1 Dr. Henle,2 and others. Before I had seen the opinions of these authors, I had, in my lectures, stated some arguments which appear to favour this notion, and which will be noticed again when speaking of infection. It may here, however, be remarked, that the chief facts which afford a countenance to the view are the following:— 1. Epidemic diseases resemble the effects of the blight insects, by ap- pearing and disappearing without evident cause, in uncertain places and at uncertain periods. 2. Unusual swarms of insects, and various epidemic visitations have been frequently remarked as occurring toge- ther, although it must be confessed that no uniformity has been found to obtain in either the characters of the insects, or the diseases. 3. Fresh proofs are continually coming under notice of the existence of parasitic animals and plants in liAdng animals, often, too, unmistakeably present- ing themselves as causes of disease: this is seen in intestinal worms and other entozoa, the acari of itch, and the rot-worm of sheep.3 4. The history and symptoms of such epidemic diseases, as cholera and influ- enza, are in no way inconsistent with the hypothesis that they are caused by the sudden development of animalcules from ova received into the blood. It must be finally stated, however, that there is an entire deficiency of all direct observations which could confer support on this hypothesis; and, perhaps, it may also be objected to it, that the seasons in which epidemics sometimes appear, are not always those most favourable to the development of animalcule life.4 (3.) INFECTIOUS POISONS. 93. The terms infection and contagion are applied to the production of a disease by the influence of a morbid matter proceeding from the body of a person who is, or has been, the subject of the disorder. They 1 Medical Notes and Reflections, 1840, p. 597. 2 Pathological Researches, British and Foreign Medical Review, April, 1840. 3 Aregetable parasites, too, often appear in the same light, as instanced in the myco- dermatous vegetations of porrigo, and pityriasis versicolor. (See Sprenger, Canstatt's Jahresbuch. 1851.) And in the parasitic algse of aphtha. (See Robin, Histoire Nat. des Vegetaux Parasites. 1853.) Gruby, Comptes Rendus, t. xlii. Bennett, Trans. Royal Soc. Edin., 1842. 4 The prevalence of the south-east wind has been observed to be particularly favour- able to the increase of both cholera and influenza; and I cannot but think that this has some connexion with the general tendency which the former shows to spread chiefly from east to west. Has the morbific power of this wind aught to do with the haziness of the air which commonly prevails with it?—a haziness perceptible in the country remote from smoke and quite distinct from fog? AVhat is this haze ? In the west of England, a hazy day in spring is called a blight. Ehrenberg has discovered by the microscope that wind deposits a fine dust, even on mountain tops, which has almost an identity of character wherever found, and which contains in addition to various earthy and oxy-metallic matters, fragments of fossil shells and shields of extreme minuteness. Organic exuviaj of this kind have been found on the coast of Africa, which seem to be the same with deposits lying near the summits of the Andes. Numerous facts seem to indicate that there are currents in the upper regions of the atmosphere that are equal to the task of transmitting subtle organic materials from one hemisphere to the other. 88 EXCITING CAUSES OF DISEASE. imply, in short, disease produced by communication. The proofs that disease is sometimes thus propagated from one individual to another are, first, the general one, that those who have intercourse with the sick, are affected in much greater numbers than those Avho hav^e not (§ 12;) and, secondly, the direct and individual act of infecting a healthy person with matter taken from a person in disease. This lat- ter plan, although available only in some forms of infectious disease, may nevertheless be considered as a sufficient proof of the general fact of contagion—that is, of the power of disease, under certain circum- stances, to propagate itself.1 94. I have just alluded (§ 93,) to there being different ways in which infection may operate; and may now specify three distinct modes in which it may do so:— (1.) Infection through wounds, or an abraded surface; this is what is commonly misnamed inoculation: it is instanced in hydrophobia, where the morbid matter is contained in the saliva, or guttural mucus of the rabid animal; and in coA\r-pox, where it is afforded by a specific vesicle. 95. (2.) Infection by contact, different parts of the body being, howT- ever, only susceptible of different diseases; this is contagion properly so thus called: thus the urethra and conjunctiva only suffer in gonor- rhoea, the vicinity of the external openings of the passages in syphilis, the skin in scabies, the scalp of the head in porrigo—in all these cases the morbid matter that effects the mischief issues generally from simi- lar parts. 96. (3.) Infection by exhalations in the breath, or cutaneous or other secretion; conveyed through the air to the mouth and air pas- sages: as instanced in the case of measles, scarlatina, hooping-cough, typhus, and other infectious fevers. 97. Some diseases are capable of propagating themselves by several of these modes; small-pox, for instance, may be communicated by in- fection through punctures in the skin (§ 943) by application to the eye (true inoculation, § 95,)—and through the general mass of the respi- rable air (96:) probably inoculation might also be effected Avith other febrile poisons, if they could be procured in the same palpable form as the matter of small-pox. All this merely shows that the matter of in- fection can exist suspended in the air, as well as in a fluid or solid state; and that it may accordingly get access to the system by diffe- rent avenues as it is in the one or the other of these. It is pretty clear, too, that the poison of infection may sometimes be conveyed by articles of clothing, bedding, or household furniture. This is the case with scarlatina, small-pox, and perhaps the plague, but in these matters popular prejudice generally goes beyond the truth. 98. Many of those who are skeptical regarding the reality of infec- tion, direct their objections only against aerial communication, and do not question the other modes. But the real difficulty of the case is, not that infectious matter may be diffused through the air—our sense 1 Some facts, and able arguments, tending to establish the existence of contagion in cholera and other epidemics may be found in a paper entitled "The Exciting Causea of Epidemics," by Professor Alison, in the Brit, and For. Med. Chir. Rev., Jan., 1854. PROPERTIES OF INFECTION. 89 of smell informs us that animal effluvia are constantly so diffused—but that infection can take place by any mode; that is, that disease should be able to propagate itself. There are only two parallel cases in na- ture, in which analogous actions take place. One is that of what is called septic matter, leaven, or ferment; a little of which being intro- duced into organic matter promotes changes and decompositions in it.— "A little leaven leaveneth the Avhole lump." This is supposed by Lie- big and other chemists, to be a chemical action; operating in the manner of heat, by altering the molecular relations and affinities of compound principles; as, for example, when some such protein compound as glu- ten in a certain state of decomposition, promotes the conversion of starch into sugar, and of sugar into lactic acid, and then this into bu- tyric and carbonic acids. It has, on the other hand, been maintained by Turpin, Cagniard De la Tour and others, that fermentation is caused by the production and growth of living molecules of a vegetable nature (torulse,) which have the power to modify the affinities of the material in which they are developed, and that it spreads by the mul- tiplication of these living bodies. If this notion be based in truth, it transfers the explanation of leaven or ferment, into the next category (§ 99.) 99. The other case analogous to the propagation of disease by infec- tion, is that of the vital power of generation; in this case, organized matter propagates itself in the animal and in the vegetable world. Does then the poison of contagion consist of animal ova, or vegetable seeds? Are infectious diseases results of the invasions and operations of living parasites disturbing in sundry ways the functions and struc- tures of the body, each after its own kind, until the vital powers either succumb before them or succeed in expelling the invaders from the system? (§ 16.) Such an opinion has been many times proposed, and is, in a degree, implied in the term incubation, (sitting on eggs to hatch them,) which is commonly applied to the period that intervenes be- tween the reception of the infection and the first appearance of the symptoms. The notion, indeed, receives support from the phenomena of itch, which certainly infects through an insect, the itch-mite, and spreads by this animal's propagation; and from those of porrigo, or favus, Avhich is now known to depend on a minute parasitic vegetable, and to infect through its seeds or sporules.1 It may however be ob- jected, that these are instances of mere local disease, and by no means parallel with the case of infectious fevers, or syphilis, in which the whole system is affected. It might be expected that small-pox and cow-pox would throw some light on this difficult subject, because the infectious matter of those disorders is found in the incipient pustule; but this has not hitherto proved to be the case. M. Gruby states that he has discovered a few animalcules in the lymph of the variolous vesicles, but its disease-pro- ducing power has not been traced to these creatures. 100. There are certain general properties in all forms of infection 1 Schonlein, Muller's Archiv., 1839, p. 82. Gruby, Gazette Medicale, Juillet 17, 1841. Robin, Hist. Nat. des Areg6taux Parasites. 1853. 90 EXCITING CAUSES OF DISEASE. Avhich seem rather to favour the notion that they are dependent upon parasitic creatures, and which further deserve to be mentioned on ac- count of their practical importance. Infectious matter is destroyed by a temperature that is higher than 120° Fahr., and by strong che- mical agents, especially chlorine; its activity is impaired by cold; and in the case of aerial infection, is rendered harmless by intense cold and free ventilation. Hence many infectious diseases cease when hard frost sets in. On the other hand, Avarmth, closeness, and filth, increase the virulence of the mischief, and become, as it were, a nursery of pestilence. Nothing tends to promote the spread of an infectious dis- ease more than crowding together many people who are suffering un- der it. Each one is then a separate source of contagion; and as these sources are multiplied in an apartment, the contained ak" becomes more contaminated in proportion. This is the chief reason why medical at- tendants and nurses escape infection much more rarely in fever hos- pitals and wards, than they do in hospitals Avhere the fever patients are widely distributed among persons suffering from other disorders. The greater number of infectious disorders, especially those which have the character in the most marked degree, leave the system more or less free from liability to their recurrence. This immunity, however, diminishes somewhat with lapse of years. A large proportion of those who have once had measles, small-pox, or hooping-cough, never take these disorders again, even although fully exposed to the infection. Some, however, do catch them again after the lapse of many years; most of these exhibit a much milder type of the affection than is usual in a first attack. This comparative security against a repeated infec- tion is involved in much mystery, but it is attributed by Liebig, and others who favour the zymotic, or fermentation hypothesis, to the ex- haustion of a certain material which is the subject of the fermentative change, and wThich is considered to be not easily again reproduced. All this is, however, pure hypothesis, and unsustained by any trust- worthy facts. [The too frequently repeated visitations of epidemic cholera, have left behind them a few hints that may help to guide future investiga- tors in the right direction, Avhen they seek to determine the nature of the concealed causes of epidemic and infectious diseases. There can ~- be no doubt that cholera is caused by some subtle poison which travels. Its path may be followed almost as if it left visible traces of its foot- steps. It is equally clear that it avails itself of material means of transport. Instances have occurred again and again, where the clothes in which cholera patients have died have communicated the disorder to healthy persons. But it is no less clear that this subtle agent re- quires a prepared recipient in order that it may become operative for evil. Comparatively few persons are susceptible to its action, even when it is rendered very intense by confinement in impure and badly ventilated apartments. Cholera, then, very aptly illustrates what has been already said regarding the necessity of predisposing and exciting influences conspiring for the production of disease. The human body is capable of being predisposed to become affected by cholera through the operation of various debilitating agents, but it does not even then DISTINCTIONS OF ZYMOTIC POISONS. 91 contract the disease, unless it is exposed to action of the peculiar sub- tle poison that broods unseen in the air, and marches through its trans- parent spaces, bent on the errand of death. But there is this highly important and interesting peculiarity about the poison of cholera,—although it propagates itself, it is not able to do so, unless a certain material is provided for it to feed upon at the time. It must have moisture and exhalations from decaying organic matters, or it cannot thrive, and reproduce itself. If these essential supports are wanting, it makes no progress, and disappears. The cholera poison spreads centrifugally from any focal point in which it has been called into existence, as waves of water extend round a spot into which a stone has been dropped, growing weaker, however, as it spreads, and at last giving no appreciable token of its existence, un- less it crosses some locality in which the material elements of the poi- son are collected in a very concentrated state, some fated spot in which moisture and the products of* decomposition dwell. Then the active poison is again called into existence out of these matters. A new focus of infectious influence is made, and from this the epidemic contagion again spreads centrifugally as from a new centre of departure. The latent material of the cholera poison may be likened to the charcoal, nitre and sulphur, that lie side by side in the grains of gunpowder. The explosive substance is there, but no explosion takes place until the quickening spark comes. Then the consuming flame breaks out. Moisture and putrefactive effluvia are the rough material of cholera poison, but this material is never worked into its effective and finished state, unless under the presence of poison already complete and active. Hence it is that the cholera poison travels, but only through regions of moisture and filth; and hence, too, it is that the disorder grows milder as it spreads, but again breaks forth in certain spots with re- newed virulence from time to time. It is curious that either the zy- motic or the parasitic theory of infection may be supposed to receive support from these considerations. It may be deemed either that the infection finds nevr material that it can change into a morbific agent like itself by fermentation; or on the other hand that the living para- sites alight upon deposits of food which they are able to assimilate and conArert into an offspring like to themselves. So much for hypothesis. —Note by Dr. Mann.~\ 101. It may be useful again to point out the characteristic peculiari- ties of infectious, endemic and epidemic diseases; for these peculiarities are so many proofs of the reality of infection viewed as an immediate cause of disease. Infectious diseases first attack individuals in some given locality, and then gradually spread in the vicinity, or in the direction in which there is most human intercourse. If care be taken, early and completely to separate the diseased from the healthy, the disease does not spread among the latter. 102. Endemic diseases attack many indiAriduals simultaneously in certain confined localities, (§ 81,) and do not spread beyond these localities; separation of the sick from the healthy does not give the latter security; but removing the healthy to another spot does. 92 EXCITING CAUSES OF DISEASE. 103. Epidemic diseases simultaneously attack many individuals over a wide extent of country (§ 88:) but do not increase particularly in the vicinity of those first affected, nor yet in proportion to intercourse with these, but rather in proportion to the prevalence of certain conditions that are of the nature of predisposing or determining causes (§ 19.) 104. It must always be borne in mind that some diseases are sus- pected to originate and spread by more than one of these modes. This is probably the case with typhus fever, plague, cholera, and dysentery. It has been already mentioned that infectious diseases, like small-pox, scarlatina, and measles, are occasionally increased and modified by epidemic influences (§ 90, 91;) the same thing may also be stated of some endemic maladies. The unquestionable aggravation of contagious and epidemic complaints in consequence of endemic impurities, (§ 85,) makes it plain that all these several causes may operate conjointly. It is under such circumstances of aggravation, combined with strongly prevailing predispositions, induced by famine (§ 21,) fatigue (§ 23,) confinement (§ 22,) defective supply of air (§ 24, 72,) or mental depres- sion (§ 28,) that epidemics not only spread more rapidly, but also as- sume so intense a form, that they become very destructive, and so earn for themselves the right to be called malignant and pestilential. The direct operation of most of this class of morbific causes is de- pressing, so that where these influences are strongest, the resulting disease is the most sure to wear the character of adynamia, asthenia, or prostration of the vital poAvers. As they exhibit influences directly noxious to life, they are commonly designated specific poisons. But there is in the system the antagonist principle of vital resistance (§ 16,) which leads to various processes of reaction, exhibited in different de- grees, according to the relative strengths of the poison and of the re- sisting power, and often also according to the absence or presence of cognizable agents which act at the same time as predisposing, deter- mining, or co-operating causes. For instance, in warm weather the poisonous influences are generally strong (§ 84, 100,) and the bodily poAvers weak (§ 24;) the resulting disease is then consequently one of more complete adynamia. In moderately cold weather, on the other hand, the specific poison is less intense, and the system more ready to react, not only against it, but also against the cold which is operative with it; this leads to a more inflammatory type in the consequent dis- ease (§ 79, 81.) The zymotic theory of epidemic, endemic, and infectious influences, affords a very reasonable explanation of the decomposition and putre- faction which they work in the blood, and subsequently in all the fluids and solids of the body. Dr. Carpenter points out1 that there is one condition very likely to dispose the body to suffer from their inju- rious influence, namely, the presence in the system of an azotized matter tending to decomposition, whether arising from a rapid disinte- gration of materials of the body, as occurs after child-birth, accidental injuries, surgical operations, excessive fatigue, or extreme privation,— or caused by impaired action of the depurating organs of respiration 1 Brit, and For. Med. Chir. Rev., Jan., 1853. ANTIDOTES TO ZYMOTIC POISONS. 93 and excretion, in consequence of close confinement in impure air, ex- haustion of vital power from intemperance and habitual excesses,—or directly introduced in the form of unwholesome food in a decaying state (§ 35.) 105. The means that have been found most effectual in preventing the spread, and of counteracting the effects of zymotic poisons are chiefly of the nature of antiseptics, which may operate without as well as within the body,—and stimulants, tonics, and eliminants, whose in- fluence is limited to the living structure. Of the numerous class of agents to which an antiseptic property is ascribed, there are two which especially deserve mention, as having been proved to be highly useful as disinfectants, or purifiers from the contaminating matters of infec- tion and malaria; these are chlorine and charcoal. Chlorine seems capable of destroying all kinds of zymotic poison, and may be usefully employed to purify the air, walls and floors of infected houses; and in a liquid state added to excreted matters, it removes their fetid effluvia. But its acrid qualities limit its use in inhabited rooms, and it can be applied only in a very diluted state as an internal or external remedy. Charcoal, recently prepared, is equally efficacious as a purifier, and its innocuous properties make it very eligible for use in a great variety of ways. Placed in shallow dishes in infected rooms, it speedily ab- sorbs from the air all offensive effluvia, and destroys all bad odours.1 Applied in a poultice to sloughing sores or ill-conditioned ulcers, it ac- celerates the decomposition and removal of the dead parts, whilst it removes their foetor, and relieves much of the pain and irritation atten- dant on them. I have employed it with great advantage in an enema with opium and sulphate of copper in the worst forms of dysentery, in which the putrid and bloody discharges speedily lead to fatal prostration; it ahvays relieved the dysenteric symptoms and corrected the foetor of the discharges, and in two cases of the worst aspect the patients re- covered. How far the use of charcoal in a respirator, as recommended by Dr. Stenhouse, may prove a safeguard against infection, can only be proved by extensive trials; and in this as well as in many other ap- plications, it well merits the attention of the profession. Its utility in gangrene and fetid abscess of the lung, in empyema, and advanced stages of tuberculous disease, can scarcely be questioned. The other remedies, to be opposed to the influences of zymotic poi- sons, are stimulants, which counteract their depressing influence; tonics, which, by increasing the tonicity of the vascular system, prevent the visceral congestions Avhich are among their worst effects; and eliminants, which promote the expulsion of the poisons from the body. The ap- plication of these remedial agents in the cure of zymotic diseases, be- longs to special therapeutics; but their use as preventives, to counteract the operation of the poisons, as exciting causes, is worthy of attention 1 Dr. Stenhouse has shown that charcoal has no antiseptic property in itself; in fact it hastens the decomposition of any organic matter with which it is placed in contact. Its purifying influence depends on its property of absorbing and condensing in its pores any gases or vapours, and by this condensation promoting their oxidation and conversion into innocuous matters. Thus sulphuretted hydrogen is converted into sulphuric acid and water; carburetted hydrogen into carbonic acid and water; cyanogen into carbonate of ammonia, &c. 94 EXCITING CAUSES OF DISEASE. in this place. It has often been remarked that a considerable propor- tion of the persons who are exposed to malaria or infection do not con- tract the diseases which result in other cases, and yet some exhibit proofs that the poison has really entered their system. Thus in aguish districts a healthy person may have a severe headache; but this soon passes off. During the prevalence of scarlatina, such an individual may have a sore throat of a day's duration; and Avhen cholera prevails, few escape without more or less of a transient diarrhoea. But the morbific influence goes no farther, being successfully resisted and pro- bably expelled by the natural powers. Now there may be others in Avhom these natural powers are inadequate to this task, unless they are aided by some of the remedial agents before mentioned. Thus to per- sons with languid circulation and deficient strength, a moderate amount of wine or other proper stimulant, judiciously combined with food at meals, may supply the wanting vigour of resistance. To those with a weak soft pulse, with consequent liability to congestions, small doses of quinine, or other tonic, repeated twice or thrice daily, may sustain the balance of the circulation against the operation of the cause; and finally, to those whose excreting functions are torpid, the assistance of such medicines as may moderately augment the defective excretions, may prove the means of delivering them from the ulterior effects of the poison, In illustration of this last suggestion I may adduce the well known fact ascertained by Orfila, that arsenic and other poisons might be given to animals without deleterious effect, only so long as they were combined with diuretics and other eliminants. 95 CHAPTER II. PATHOLOGY (PROPER)—THE NATURE AND CONSTITUTION OF DISEASE. 106. Disease is a change from the natural condition of the function or structure of the body, (§ 6, et seq.;) but the change is generally more or less complex, involving several elementary functions or struc- tures ; it is therefore obvious that we cannot obtain an accurate know- ledge of the nature of disease, until we have carefully studied the component parts of which it is made. As the anatomist or physiologist examines structures and functions by separating or analyzing them into their constituent parts, before he enters on their contemplation as a whole, so should the pathologist study the constituent parts, or ele- ments, of disease, before he attempts to understand their combinations. A neglect of this precept has greatly retarded the advancement, nay, even the formation, of pathological science. Men enter upon the very complex problems of inflammation and fever, before they have made themselves acquainted with the elementary properties of textures, or even of vessels. The result has been, that the most profound reasoning and ingenious speculations have been wasted on such nonentities as spasm of the extreme vessels, and increased action of the capillaries: and even observation has been confused by the complexity of the sub- jects that are too suddenly brought before it. The chemist, while pursuing his examinations, finds that there are some principles or elements which he cannot analyze or divide farther; these he calls ultimate or primary elements: others, again, he discovers to be compounds, which he can resobre into primary elements; but which are so simple, occur so constantly, and act so distinctly in com- bining, and in giving properties to complex matter, that he is induced to name them proximate principles, or secondary elements. The phy- sicist or natural philosopher, makes a similar distinction in the matters with which he deals. 107. So too it should be with the physiologist and pathologist.1 There are the healthy and diseased primary, or ultimate elements of struc- ture—muscular fibre, nervous matter, vascular structure, and the ele- mentary tissues of membranes, glands, skin, and other like textures; and there are primary elements, healthy and diseased, of the functions 11 have pursued this synthetic mode of teaching general pathology, in my lectures, since the year 1839. I am not aware that it has been as fully used by any other writer, although several (among them Andral and Carswell) have partially recognised it in classing the objects of morbid anatomy; and my friend, Dr. Symonds, has alluded to the parallel case of chemistry, and has actually employed the term, proximate princi- ples of disease, in the same sense in which I use it.—Library of Practical Medicine, vol. i., Pathological Introduction. -96 PRIMARY ELEMENTS OF DISEASE. of these same structures—irritability, tonicity, and nervous properties, to which Ave may add, because at present we cannot analyze it, the power of secretion and nutrition; and lastly, there are the constituents of the highly important fluid which furnishes the material of the elemen- tary tissues, namely the blood, which are also subject to morbid altera- tions of structure and derangement of function. But there are also secondary or proximate elements of disease, composed out of these primary elements, but which are themselves simple, in comparison with the complex conditions of disease that they combine to produce. 108. But again, disease, affecting the several elementary and proxi- mate structures and functions of the body, varies both in degree and in hind; the degree, including excess and defect, alterations of a plus and minus nature: and kind, relating to changes not coming under either of these heads, but characteristically expressed by the termper- version. By employing these several distinctions Avhile considering deviations of structure and function, Ave are able to construct a simple and comprehensive classification, Avhich embraces within itself all the most important topics of general pathology. 109. The folloAving table presents this classification, so far as the primary or ultimate elements of disease are concerned. STRUCTURAL CONSTITUENT. Contractile fibre Nervous structure PRIMARY ELEMENTS OF DISEASE. DISEASE. 1 ITS FUNCTION. j Irritability. \ Tonicity. Tubular (the con-"] Sensation. ductor of nerve J Aroluntary motion. force.) {involuntary motion, A'esicular (the ge- j (excited motor neratorandcombi- j action.) ner of nerve force.) J Sympathetic action. Secretion. STRUCTURAL DISEASE. Secreting structure f Red corpuscles. AVhite corpuscles. Fibrin. Elementary | Albumen. components -j Oil, and combustive of blood Elementary changes in the blood matters. Inorganic ingredients I (saline and mineral.) ( Water. By respiration. By secretion'. By nutrition. By foreign matter. Excessive.—Hypertrophy. Deficient.—Atrophy. | [ Perverted.—Degeneration. 110. In treating