Outlines of pathology and practice of medicine

Front matter

OUTLINES

OF

PATHOLOGY

Preface

In attempting to compress, within the limits of a Text-book for Lectures, the facts which seem to me best ascertained in regard to the nature, progress, and symptoms of Diseases, and the effects of Remedies upon them, it has been my object to simplify, as far as possible, both the diagnostic marks of Diseases, and the practical rules for their treatment, — dwelling only upon those, an accurate knowledge of which may be acquired without much difficulty, and on which it has appeared to me, in practice, that we can rely with most confidence. I have endeavoured to connect these practical rules and directions with as full a statement as the limits of such a work will permit, of the grounds of those opinions, in regard to the causes, the intimate nature, and fatal tendency of Diseases, which seem to me, in the present state of our knowledge, to be supported by the best evidence ; because notwithstanding all that has been said,

VI

PREFACE.

and may be said, against Medical speculation, I am fully convinced of the truth of the observation of Dr Cullen, that " at all times the Practice of Medicine has been, and still is, with every person, founded more or less upon certain principles established by reasoning from which it evidently follows, that any one who undertakes to teach the Practice of Medicine must be prepared to explain the grounds of his opinions ; as well as to state the facts, and describe the appearances, on which he is to found his practical precepts.

It may be thought by some of those who have attended closely to the recent progress of Microscopical and Chemical inquiries, into the structure and functions of living bodies, in health and disease, that I might have laid down more accurate and comprehensive principles in regard to the nature of various diseases, founded on those inquiries ; but any such principles would at this moment have been deficient in certainty and precision ; and I have therefore not thought myself justified in goingfarther, than to point out the questions in Physiology and Pathology which especially demand the prosecution and completion of these inquiries ; — always, however, under this reservation, that the laws of Chemistry, as well as of Mechanics, are subject to a certain modification in all living bodies; — and to express in general terms my conviction, that these are the most important questions which remain to be solved in those sciences.

I should probably have thought it right to enter on

PREFACE.

vii more details in diflPerent parts of this work, and frequently to refer to tlie books in wHcli minute information regarding individual diseases is to be found, had I not been anticipated by the fuller and elaborate works of Dr Copland, Dr Tweedie, and Dr Craigie, one or other of which is likely to be in the hands of almost every one who is now qualifying himself for the duties of the medical profession.

PAGE

OF FEBRILE DISEASES, 92

DIVISION I.

OF INFLAMMATORY DISEASES, 94

Chapter I

Of inflammation in general, .... 95 Sect. I. Of the Primary and Characteristic Phenomena of Inflammation, . . 93 Sect. II. Of the Present State of our Knowledge of

the Essential Nature of Inflammation, 108 Sect. III. Of the Remote Causes of Inflammation, 140

Sect. IV. Of the Local Effects, and Anatomical Characters of Inflammation, . . . 145

Sect. V. Of the Symptoms resulting from these

Effects of Inflammation, . . 163

Sect. VI. Of the Varieties of Inflammation, . 173

Sect. VII. Of the Fatal Terminations of Inflammation, 212

Sect. VIII. Of the Treatment of Inflammation, 213 CHAPTER II.

Of inflammation of the air- passages and lungs, . 251

Sect. I. Of Cynanche Tonsillaris, . . . 251

Sect. II. Of Cynanche Laryngea, and Trachealis, 257

Sect. III. Of Bronchitis, .... 262

Sect. IV. Of Peripneumony, .... 275

Sect. V. Of Phthisis Pulmonalis, . . . 284

Sect. VI. Of Pleurisy, Acute and Chronic, . • 290

CONTENTS.

XI

Chapter III. Page

Of inflammations of the heart and bloodvessels, 295

CHAPTER IV. Of inflammations of the viscera of the abdomen and

PELVIS, .... 307 Sect. I. Of Hepatitis, . . . . 307 Sect. II. Of Peritonitis, .... 313 Sect. III. Of Inflammation of the Mucous Membrane of the Stomach and Intestines, 321 Sect. IV. Of Inflammation of the Kidneys, and other

Urinary Organs, . . . 328 Sect. V. Of Inflammation of the Uterus, . 324

CHAPTER V. Of inflammations of the nervous system and organs of

Sect. I. Of Inflammation of the Brain, . . 337

Sect. II. Of Inflammation of the Spinal Cord, 348

Sect. III. Of Inflammation of the Eye, t . 352

Sect. IV. Of Inflammation of the Ear, . . 356

CHAPTER VI. Of inflammations of the organs of locomotion and

SUPPORT, .... 359 Sect. I. Of Rheumatism, . . . . 359

Sect. 11. Of Gout 366

Sect. III. Of Inflammation of the Periosteum, Bones,

and Joints, . . . . 369

CHAPTER VII. Of inflammations of the integuments, xii

CONTENTS.

DIVISION 11.

PAGE

OF FEVERS PROPERLY SO CALLED, . . . . 389

CHAPTEE I.

Of idiopathic fevers, ...... 389

Sect. I. Of the Diagnostic Symptoms and Varieties

Sect. II. Of the Appearances on Dissection after

Idiopathic Fevers, . . . 406

Sect. III. Of the Remote Causes of Idiopathic Fevers, 417

Sect. IV. Of the Pathology of Idiopathic Fevers,

and of their Fatal Terminations, 430

Sect. V. Of the Treatment of Idiopathic Fevers, 448

CHAPTER II.

Of the eruptive fevers, or contagious exanthemata, 467 Sect. I. Of the Smallpox, .... 471 Sect. II. Of the Measles, .... 477 Sect. III. Of the Scarlatina and Malignant Sore- Throat, 481

Sect. IV. Of the Erysipelas, . . . . 490

y' Sect. V. Of the Plague, . . . • 495

PAET III.

OF CHRONIC OR NON-FEBRILE DISEASES, . 501 CHAPTER I.

Of chronic or non-febrile diseases in general, . . 501 Sect. I. General View of the Modes of Diseased Action observed in Diseases of this class, ...... 502

CONTENTS.

Xlll

Sect. II. General View of the Kinds of Morbid Structure observed in Diseases of this class, . • •

Sect. III. General View of the Causes and History of these Chronic Diseases, and of the Objects of Practice in regard to them, 520

CHAPTER II.

Of chronic diseases of the air-passages and lungs, 529

CHAPTER III.

Of chronic diseases of the heart and bloodvessels, 533 Sect. I. Of Chronic Diseases of the Heart, . 533 Syncope, ^

Palpitation, ^ Functional and Organic.

Angina Pectoris, )

Cyanosis,

Sect. II. Of Chronic Diseases of the Arteries, . 551 Aneurism.

Spontaneous Gangrene.

Sect. III. Of Chronic Diseases of the Circulation in, and Exhalations from, the Capillary

Vessels, 559

Congestions of Blood.

Hsemorrhages.

Dropsical Effusions.

CHAPTER IV.

Of chronic diseases of the organs of digestion and

assimilation. . . . . . . 579

Sect. I. Preliminary Observations, . . 579 Sect. II. Of Chronic Diseases of the Stomach, 586 Sect. III. Of Chronic Diseases of the Liver, Pancreas, and Spleen, . . 598

XIV

CONTENTS.

PAGE

Cholera.

Jaundice.

Granular Degeneration, and other Organic Diseases.

Of Chronic Diseases of the Intestines, 611 Diarrhoea.

Colic.

Tubercular and other Organic Diseases. Worms.

Ascites.

Epidemic Cholera.

Of Chronic Diseases of the Function of

Assimilation, . . . 633 Scurvy.

Dry Gangrene.

Kickets, Diabetes.

Lithiasis.

CHAPTER V.

Of chronic diseases of the organs of urine and generation, . . . 653 Sect. I. Of Chronic Diseases of the Kidneys, 653 Sect. II. Of Chronic Diseases of the Bladder, 658 Sect. III. Of Chronic Diseases of the Male Organs

of Generation, . . . 659

Sect. IV. Of Chronic Diseases of the Uterus and

Ovaria, .... 662 Amenorrhoea.

Menorrhagia.

Leucorrhoea.

Organic Diseases.

Sect. IV.

Sect. V.

CONTENTS.

XV

CHAPTER VI.

PAGE

Of chronic diseases of the nervous system and organs

OF sense, . . . 676

Sect. I. Preliminary Observations, . . 676

Sect. II. Of Apoplexy and Palsy, . . 687

Sect. III. Of Spasmodic Diseases, . . 698

Convulsions and Epilepsy.

Chorea.

Hysteria and Analogous Spasms.

Tetanus.

Hydrophobia.

Sect. IV. Of Disordered Sensations, . . 716

Amaurosis.

Anaesthesia.

Neuralgia.

Spectral Illusions.

Sect. V. Of Mental Disorders, . . . 721

Amentia.

Somnambulism.

Dementia.

OUTLINES PRACTICE or PATHOLOGY

AND

OF MEDICINE.

PART L

PRELIMINAHY OBSEEVATIONS.

As the object of Physiology is to deliver the history and explanation of all the phenomena by which the living body is distinguished from the dead, so the object of Pathology is to describe and explain all the phenomena by which the diseased states of the living body differ from the healthy ; and we call all states of the living body diseased, in which there are such deviations from its natural condition as cause suffering or inconvenience, or endanger life.

A slight attention to this subject is sufficient to shew, that there are many facts in regard to the operation of external causes on the human body, and the modes of diseased action assumed by its different organs, which could not possibly have been inferred from our knowledge of the structure and healthy action of parts, which

PEELIMINARY OBSERVATIONS.

are made known to us only by observation of the diseased conditions of tbe body themselves, and can only be properly generalized by an induction strictly confined to this department of knowledge.

The fewer and more comprehensive these ultimate facts or laws in this department of nature, the more successful must the induction be regarded ; and some of them have been already so far ascertained, as to enable us to treat the subject in some measure synthetically.

The simplest exemplification of these ultimate facts in Pathology is to be found in cases of sudden death, and in the action of violent injuries, and we, therefore, premise a short account of difierent fatal injuries, to discussions on the pathology of the difi'erent diseases.

Chapter I. Of Cases Of Sudden Or Violent Death

The operation of all causes of sudden or violent death may be referred ultimately to two modes of injury, which are in some cases perfectly distinct, although in others they are evidently blended. We cannot, indeed, arrange the causes of violent death strictly according to these differences in the mode of their action, because the same causes appear to act, under different circumstances, sometimes chiefly in the one way, and at other times in the other ; but we can point out that their fatal effects are always produced, either by their directly depresdng or suspending the vital action of the organs of circulation^ — or else, by their obstructing the arterialization of the bloody and therefore, according to principles known in Physiology, arresting the circulation at the lungs.

We know farther, that the first effect, or what may be called in general death by Syncope^ or beginning at the Heart, may be produced in two ways : 1 . By a cause acting on the system, as a concussion or shock, depressing the vital powers by which the blood is moved ; 2. By abstraction, sudden or gradual, of the vital stimulus ; — and that the second effect may be produced also in two ways, 1. By injury of the Nervous System, arresting respiration by causing insensibility, i. e. producing death by Coma^ or beginning at the Brain ; and, 2. By

OUTLINES OF PATHOLOGY AND PRACTICE.

direct impediment to tlie access of air to the lungs, producing what is strictly called death by Asphyxia^ or. beginning at the Lungs.

To these principles we can ascribe the known effects of the following kinds of injury; and having illustrated these, we may afterwards refer to them with advantagCy as the facts most analogous to the changes that constitute disease, and especially to those circumstances of disease which are immediately dangerous to life.

I. It is to be expected, from what we know of the functions of the Nervous System^ that Injuries affecting it should impair, more or less completely, the sensations, the mental powers, and the voluntary motions ; but they become dangerous to life only in the ways already specified, inasmuch as they affect the fundamental function of Circulation, either directly, or through the intervention of the Respiration.

1. The most violent injuries, affecting the Nervous System, suddenly arrest, or greatly impair, the motion of the blood in all parts of the body, i, e. they produce a state of Syncope or faintness ; the heart's action either suddenly ceasing, or becoming very feeble ; the pulse small, or imperceptible, and the surface cold, often damp ; at the same time that sensation and voluntary motion are suspended. This direct effect on the circulation of violent injuries of the brain was overlooked by Bichat, but is well illustrated by Dr Wilson Philip ; and has long been known to practical men, as constituting the most characteristic part of the first symptoms of general Concussion of the braiii, as distinguished from more partial Compression of it.

The experiments of Legallois and Dr Wilson

OF CASES OF SUDDEN DEATH.

Philip fartlier sliew, that this effect on the heart's actions, and on the motion of the blood in the capillaries, may result from injury of any part of the hrain or spinal cord, if it extend to large portions of the nervous matter ; and many examples inform us, that when concussion is general over the whole system, it is frequently fatal, in this way, without any visible disorganization being produced.

After death from affection of the nervous system, thus directly influencing circulation, the heart is sometimes found, especially in the most sudden cases, quite empty of blood (the cause of which appearance is doubtful) ; in other cases distended, but with no decided difference as to the quantity of blood in its right and left sides.

In cases of this kind, it is not quite certain that the fatal depression of the vis vita3 in the circulating system is the effect of an impression made on the nervous system; and some have supposed, that such injuries are fatal by a direct effect on the circulation in the smaller arteries, checking it so completely, as to throw a burden on the heart which it is unable to overcome. But the effects of violent injuries confined to the brain or spinal cord, as in the experiments of Wilson Philip and Legallois, are just similar to those of a general concussion ; mental causes, of powerful operation, which certainly act through the nervous system, have the same effect ; partial although violent injury of other textures has no such effect ; nor does such an effect result from suddenly stopping the flow of blood in large arteries by ligatures, or by amputation of a large limb ; and therefore it is highly probable, that general concussion of the body does act^ as is generally thought, on the vascular system through the intervention of the nervous > and tliis is one of the facts included under the general principle in Physiology, that the nervous system, although not necessarily concerned in the functions of organic life, is yet so connected with them, that, by certain changes in it, any of these functions may be variously altered, or even totally suspended.

There is great variety as to the amount of injury which will produce, in different individuals of the human species, the sedative effect on the circulation now in question ; and as to the duration and termination of that sedative effect, which sometimes abates quickly, and sometimes gradually increases till it is fatal, some hours after the injury.

There appears to be a variety also in the part of the circulation chiefly affected by such injuries. In some instances the circulation on the surface appears peculiarly affected, and the heat of the surface is reduced much more than in others, where the hearths action is equally depressed. In experiments by Chossat, the heart's action was for some time little affected by certain injuries of the brain, which checked the circulation in the capillaries so completely, as to suspend the secretions and the evolution of heat. When the spinal cord has been severely injured in the human body, below the neck, the circulation in the capillaries has generally appeared, for some time, more affected than the heart's action, although it is by gradual failure of the circulation that such cases are ultimately fatal.

There is also great variety in the alterations of the functions of the Nervous System itself, which result from such injuries, and accompany or succeed the sedative effect on the circulation. In some cases the coma is long continued and profound, in others slight and

OF CASES OF SUDDEN DEATH.

transient ; in some cases it is attended by much convulsion, in others by little or none ; in some cases it is succeeded by much headach, or by general or partial amentia or delirium, or by incessant nausea and vomiting ; and in others by none of these. And it is certain that all these varieties in the symptoms, in such cases, may be independent of any perceptible alteration of the structure of the nervous system.*

This primary effect on the circulation, of extensive injury of the Nervous System, is seldom the immediate object of practice, because if not immediately fatal, it is usually followed by symptoms of inflammation, against which the chief remedies must be directed ; but in few cases, the danger from the first effect of the concussion may be properly averted by internal and external stimuli, cautiously used.

It is an important observation, that when injuries that have affected the Nervous System, and through it the circulation, in the manner now stated, are not quickly fatal, but are followed by the slower processes, to be afterwards described, of inflammation and fever, the progress of these is frequently modified by the preceding or accompanying state of the system, likewise consequent on the injuries ; and that in these circumstances fever is apt to assume the form to be afterwards described as typhoid^ and inflammation to terminate rapidly in gangrene, f How far these facts should be relied on, as indicating the true pathology of Typhoid Fever, is still doubtful ; but it is certain that, in these circumstances, the practice afterwards to be considered as suited to typhoid fever is admissible, and sometimes decidedly beneficial.

* See Brodie, Medico- Chirurgical Transactions, vol. xiv. t See particularly Travers on Constitutional Irritation.

2. A slighter, and especially a more partial injury of the Brain, or upper part of the Spinal Cord, if its action be of sufficient intensity and duration, often produces death in a totally different way, viz. by Coma or stupor, ■ — " superstite actione cordis et arteriarum." The essential peculiarity of this kind of fatal effect of an injury of the Nervous System is, that Respiration takes place imperfectly, and ultimately is suspended, probably by reason of the defect of sensation ; and in the cases which are characteristic examples of this mode of death, the Circulation, and sometimes the animal heat, not only continue entire up to the moment when the last breath is drawn, but even survive the respiration for a short time ; during which time, of course, venous blood moves along the arteries; but the venous blood, according to the general law established in the Physiology of Respiration, soon ceases to make its way through" the capillaries of the lungs, and the circulation is therefore soon brought to a stand.

The experiments of many physiologists shew, that it is in this way only that death is produced when the spinal cord is cut in the upper part of the neck, or the head cut off, without violent haemorrhage, and without any large portion of the brain or spinal cord being crushed.

The most common injuries of the Nervous System which cause death, thus preceded by Coma, are those in which there is partial compression of the nervous matter, as by depressed bone, or effused blood, pus, or serum ; but it is in the same way that death is often produced by disorganizations of the brain, which do not necessarily imply compression of its substance ; and also by certain poisons, the effect of which on its functions does not appear to depend on alteration of the pressure on it ; and

OF CASES OF SUDDEN DEATH.

it is therefore incorrect to speak generally of sucli symptoms as indications of pressure on the brain.

We know from Physiology, that the part of the Nervous System which must be specially affected in these cases, where the failure of respiration is the immediate cause of death, must be at the sides of the medulla oblongata ; but the part visibly injured is often considerably distant from this.

There is very great variety as to the duration and degree of the insensibility, vfhich precedes the failure of respiration in such cases of injury of the Nervous System ; and as to the other affections, either of the brain and nerves, or of other organs, which may precede or attend that insensibility, such as Jieadach, delirium, somnolency, spasms, palsy, dilated or contracted pupil, preternaturally slov/, or frequent, or irregular pulse, &c. Even the function of respiration itself is variously affected in different cases of the kind, being sometimes hurried and imperfect, and in other cases unnaturally slow and deep, for some time before it is finally suppressed. After the death thus produced by injuries of the Nervous System, just as after death by asphyxia, we find, as might be expected, the blood accumulated chiefly in the lungs, pulmonary artery, right side of the heart, and great veins.

The state of Coma, succeeding to injuries of the Nervous System, with or without those accompaniments, is often successfully treated by depleting remedies, and strictly antiphlogistic regimen, when depending on increased determination of blood to the brain and its membranes, or on inflammation there ; and, in a few cases, by surgical operation, when it can be ascertained to depend on mechanical compression.

These two modes in which injuries of the Nervous System may cause death, though perfectly distinct in some cases, are evidently combined in others ; the same cause both instantly weakening the circulation and likew^ise deadening the sensibility, so as gradually to suppress the respiration. And there are many cases of injury of the head, where insensibility and faintness from the concussion immediately succeed the accident, but quickly abate, and are succeeded after an interval by insensibility with full pulse, and death in the way of coma ; which may then be confidently ascribed to compression of the brain by effused blood or serum.

There are various causes, physical and mental, w^hich affect the Nervous System, nearly in the manner of a Concussion, and are apt to produce a similar depressing, and sometimes dangerous, effect on the circulation, and the operation of which is illustrated by the facts now stated, as to the effects of mechanical injuries. They usually cause vertigo, tinnitus aurium, confusion of thought, and then often an instantaneous loss of sense^ intellect, and voluntary power, constituting what is called a complete fit of Syncope. One of these is, a sudden minution of the pressure, to which the brain and spinal cord had been previously subjected. Thus, when a depressed piece of bone, or a coagulum of blood, or a quantity of serum, which had long rested on a portion of the brain, has been removed, insensibility, and along with it sudden feebleness of circulation, have often ensued. AYhen a large bloodvessel has given way in the head, and poured blood into the ventricles (implying, in the first instance, a sudden diminution of the pressure on a part of the nervous matter), a similar result has often been observed ; and been followed by a partial re-

OF CASES OF SUDDEN DEATH.

covery of sense, and of pulse, and tlien by gradual accession of fatal coma, as tlie effused blood has increased in quantity, and compressed the brain around it.* The sudden attack of insensibility, and sudden depression of the heart's action, which may often be determined by the erect posture during bloodletting, or by rapidly removino' the fluid of ascites without substitutino' artificial compression, must likewise be ascribed to sudden diminution of the pressure on the brain, acting like a concussion ; and is illustrated by the attacks of syncope, with suspension, or great diminution, of the motion of the heart, which are often produced by rising suddenly after long stooping.

The secondary action, or reaction on the heart, of suddenly diminished pressure on the brain (even of such diminished pressure as results from previously weakened action of the heart itself), is illustrated by the well-known effect of the erect posture as a cause, and of the horizontal position as a remedy for Syncope, — not only for the affection of the Nervous System, but for the enfeebled action of the heart ; — and illustrates in its turn the influence of all those causes of syncope which act primarily on the nervous system.

One of these causes, which many persons have thought adequate to produce such an effect on the Nervous System as shall act as a concussion, is the impression made by a cannon ball, or other large substance passing with immense velocity close to the head.

A cause certainly adequate to produce fatal depression of the heart's action, and which no doubt acts through the Nervous System in like manner as a con-

* See Abercrombie on Diseases of Brain and Spinal Cord, p. 228. et seq.

cussion of the brain, is a violent blow on the abdomen, especially on the epigastrium, which has been supposed to act immediately on the great semilunar ganglion. A draught of cold water taken when the body is heated and exhausted by fatigue, has in some cases been instantaneously fatal in the same manner ; and the concussion from a violent and extensive wound of any part of the abdomen is usually fatal in the same rapid way, independently of haemorrhage, and before there is time for inflammation to be established. These facts are important, as illustrating the more gradual, but very dangerous depression of the power of the heart, which is seen even in the earlier stages of inflammation, and other acute diseases, of the abdominal viscera.

Violent injuries of various other parts of the body, especially if inflicted on a person of weakly habit, and in whom the nervous system is in a state of unnatural excitability (as from the habitual use of opium or spirits), may equally act on the footing of a concussion ; either causing sudden death, or so depressing the actions of the vascular system, as to give the typhoid form to the fever, and the gangrenous tendency to the inflammation, which are to result. This has been observed from severe surgical operations, and from extensive lacerated wounds, and bad compound fractures of various parts, even although there had been no general concussion of the body, nor insensibility immediately after the injury.*

In the cases last mentioned, it can hardly be doubted that the violence, or peculiar nature of the Sensation, which attends the injury, is the intervening link through which the vital action of the heart is sympathetically

* See Travers on Constitutional Irritation.

OF CASES OF SUDDEN DEATH.

affected ; and accordingly, we have many facts to prove, that various violent or overpowering Sensations, intense Pain, or the sudden transition from pain to ease, and likevfise certain mental Emotions or Passions, as Joy, Grief, Anger, Fear, when acting in the utmost intensity, affect the circulating system just as a concussion does, and sometimes with fatal effect, — especially when they take place in persons in a state of unusual weakness or exhaustion.

These facts do not establish, as Cullen and others supposed, a necessary dependence of the heart's action on the Brain, — a supposition which is inconsistent with facts now known in Physiology. They only concur with other facts in proving, that the heart's action is subject to an influence or control, from certain changes in the Nervous System, probably especially from changes which extend over the whole of that system, and which act at a peculiar advantage on the heart, as an organ connected, by the ganglionic nerves, with all parts of the cerebrospinal axis.*

Many of the stimulating remedies which are useful in Syncope, or in diseases threatening to end in fatal syncope, act obviously through the Nervous System on the heart. But two of the most active of these remedies, the affusion of cold water on the face and neck, and the application of stimuli to the nostrils, seem to have a peculiar mode of action, viz, exciting the act of Respiration, and thereby determining to the heart a larger quantity of its appropriate stimulus, arterial blood.

IT. The effect of very intense Heat^ applied to a pretty large surface of the body, as in an extensive burn,

* See Outlines of Physiology, p. 275.

OUTLINES OF PATHOLOGY AND PRACTICE.

or to the whole body, as in the case of a coup de soleil, is also quite similar to that of concussion ; there is often insensibility, and always, when the case threatens the most immediate danger, there is the characteristic depression of the heart's action ; and when recoveries take place from the state of collapse (as it has been called) immediately succeeding such injury in its extreme deoTee, it is often under the use of stimulatino- remedies.*

But intense heat of the sun, in other circumstances,- — especially, as it would seem, if acting more gradually on a stronger habit of body, and when there has been less exhaustion by muscular exercise, — has often produced a state of insensibility, in which the pulse has been fuller than natural, and the vessels of the head unnaturally turgid, and which has either been fatal in the way of coma, as above explained, or been relieved by copious evacuations, and cold ajDplications ; and the same cause has often produced other diseased conditions connected with a derangement of the action of vessels of the head.-j- In this case, the most injurious effect of the heat is evidently on the vascular system, exciting the action of the heart, and probably expanding the blood in the vessels ; and the brain suffers probably from increased compression by the blood; whereas in the former case, the first and chief effect of the heat appears to be on the nervous system, and the heart suffers from the violent impression made there.