Of Steep the mental and bodily functions, and deprives the sysand Torpor.tem of that natural stimulus which seems essential to the activity and vigour of the body in the male. CHAP. XV. Of Sleep and Torpor. WE have already considered the active means by which the waste of the body is repaired; but all these would have little effect, and could not indeed be carried on for any considerable time, without some general relaxation of the system. This relaxation is brought about by sleep, in which the active functions find a repose from the labours which they have undergone during the day; and in this way the system is recruited more completely than by any other means. Sleep may be considered as an affection of mind, and therefore more properly a subject of metaphysical, than of physiological speculation. It is, however, generally treated of in systems of physiology; and it will be necessary to take notice of some circumstances respecting it. We shall chiefly consider the state of the body and mind during sleep, and some of the principal theories that have been contrived to account for it. Natural sleep returns at certain intervals, which are, however, different in different animals. Most animals, and especially man, sleep only during the night, but most of the predacious species, as beasts and birds of prey, choose this time for their predatory excursions, and repose during the day. Sleep comes on with an unusual languor and lassitude; an aversion to motion; the mind becomes unfit for its usual exertions; and the desire of rest pervades the whole system. In particular, the extensor muscles lose their power of preserving the body in an erect posture; the eyelids involuntarily fall; the head bows forward; the joints bend, and the body sinks. During sleep, all the voluntary motions are in general suspended; but the involuntary actions of the heart and lungs proceed, though not so vigorously as in the waking state; the circulation and respiration being slower than usual. Most of the senses are also in a state of repose, especially those of feeling, smell, and probably of taste. Hearing is, in some animals, very acute during sleep, and they are thus enabled to escape any danger that threatens them. Some animals, as the hare, also sleep with their eyes open; and in most the impression of light, when the eyelids are raised, is very evident. The functions of digestion, absorption, and secretion, seem to proceed with greater case and activity during sleep; and as-imilation and nutrition are much promoted by this state of repose. Some of the faculties of the mind, especially the imagination, are, however, in full vigour, as appears from the dreams that take place during sleep. The duration of sleep is exceeding ly various. Among the human species, young chil dren, and very old persons, pass the greatest half of their time in sleep, while middle-aged and active people seldom sleep so much as one-third of the 24 hours. Though the returns of sleeping and waking depend much on custom, they may, however, be changed by various circumstances; and though the commencement of one of these periods happen to be altered, that of the other may remain as before. If a person is accustomed to go to sleep exactly at nine in the evening, and to rise again at six in the morning, though the time of sleep may be occasionally protracted till twelve, he will yet awaken at his usual hour of six: or if his sleep be con- Of Sleep tinued by darkness, quietness, or similar causes, till the and Torpor. day be farther advanced, the desire of sleep will return in the evening at nine. 347 Most of the causes that produce or prevent sleep, have Theory of been mentioned in the article MEDICINE, N° 94. As sleep. to the immediate cause, the opinions of physiologists are much at variance, and the theory of sleep is as little understood as that of any function of the animal economy. 349 According to Haller, sleep arises, either from a sim- Hypothesis ple absence, deficiency and immobility of the spirits, or ot Haller. from compression of the nerves, and always from the motion of the spirits through the brain being impeded. Firt That sleep is, some how or other, connected with a com- Lines of pression of the brain, appears very probable, from the Physiology, heaviness and coma that take place in cases where such § 5o5. a compression has evidently been produced; but how this compression acts has never yet been satisfactorily explained; and the obstruction that Haller supposes in the motion of the animal spirits, or nervous fluid, is gratuitous. 140 One of the fashionable doctrines of the present day Of Brown. respecting the immediate cause of sleep is, that this state is produced by an exhaustion of irritability or excitability. According to Brown, sleep succeeds a diminution of excitement, during which the excitability is either only so far diminished that it can be accumulated again, or so abundant, that the excess can be wasted, and in each case the excitement restored †. Elem. 350 Similar to this is the doctrine of Zoonomia, that sleep Med. depends on an exhaustion of sensorial power. Dr Dar- 337 win thus character zes perfect sleep: 1. The of power Of Darwin volition is totally suspended. volition is totally suspended. 2. The trains of ideas caused by sensation proceed with greater facility and vivacity; but become inconsistent with the usual order of nature. The muscular motions caused by sensation continue; as those concerned in our evacuations during infancy, and afterwards in digestion, and in priapismus. 3. The irritative muscular motions continue, as those concerned in the circulation, in secretion, and respiration. But the irritative sensual motions, or ideas, are not excited; as the immediate organs of sense are not stimulated into action by external objects, which are excluded by the external organs of sense; which are not in sleep adapted to their reception by the power of vo lition, as in our waking hours. 4. The associate motions continue, but their first link is not excited into action by volition, or by external stimuli. In all respects, except those above mentioned, the three last sensorial powers are somewhat increased in energy during the suspension of volition, owing to the consequent accumulation of the spirit of animation 4. Dartin's Thus, the immediate cause of sleep consists in the Zoonomia, suspension of volition produced by the exhaustion of sen- vol. i. § 18. sorial power; and hence, whatever diminishes the general quantity of sensorial power, acts as a remote cause of sleep. Of Sleep from the sameness of the scenery around us; and when and l'orpor. one stimulus, after long application, can arouse no more, another stimulus that in ordinary cases is less powerful, produces excitement, and keeps off sleep; an evident proof that excitability or sensorial power have not been very far exhausted. 351 Supposed sleep of plants. 352 Dreaming. 353 Somnambulism. Plants have been said to sleep. At the approach of night, many of them are observed to change their appearances very considerably, and sometimes even to such a degree as scarcely to be known for what they are. These changes happen principally to the leaves and the flowers. During the night, many leaves, according to the nature and genus of the plant, are seen to rise up, to hang down, or to fold themselves in various ways, for the protection of the flowers, the buds, the fruits, the young stems; and many flowers, to escape a superabundance of moisture, to hang down their mouths towards the earth, or to wrap themselves up in their calices. These phenomena are owing to stimuli acting from without; we may add, that most of the motions are performed at the joints where the leaves and petals articulate with the stem. A period of rest is as necessary to plants as sleep is to animals. The irritable principle cannot act long under the influence of the same stimulus, except at intervals, and the rapid growth observable in plants during the night, is a strong proof that the organs employed in assimilation had been disturbed in discharging their functions during the day, when exposed to the action of heat and light and of other stimuli. In our general outline, we had proposed introducing here an account of the phenomena of dreams, but we find that this subject has been so fully discussed under the article DREAM, that any additional remarks would be unnecessary. To this article therefore we refer the reader. Rules for the management of the body with respect to sleep, scarcely come within our present province; but as we pass so much of our time in this state, during which we are sometimes occupied in a very agreeable manner, while at others we are subject to most uneasy sensations, it is a matter of considerable consequence to take those measures which may secure to us the former, and enable us to avoid the latter. We have seen few rules better adapted to those purposes than those of Dr Franklin; but as more important matter presses for insertion within the circumscribed limits to which we are restricted, we must refer our readers to the original paper, which is published in the late 8vo edition of Franklin's Works, vol. iii. p. 437 In a few cases, not only the imagination has a full range during sleep, but the voluntary motions of the body, and even the exercise of some of the external senses, are carried on with apparently as much perfection as when the person is awake. This state is called somnambulism, or sleep-walking, and is commonly considered as a variety of dreaming. Many surprising accounts have been given of sleep-walkers. They have been known to rise, dress themselves, go out of doors, and sometimes out of a window, from which they have climbed upon the roof of a house, dig in a garden, draw water from a well, saddle a horse and ride several miles; maintain a rational and interesting conversation, and even go through a laborious and difficult literary task; and af ter having performed these exploits, they have returned Of Sleep to their bed without being conscious of what they had and Torpor. been doing. This want of consciousness appears from their remembering nothing when they awake, of whatpassed during their sleep. It is disputed whether somnambulists incur as much danger in the actions which they perform, as those who are awake, in similar circumstances. We are inclined to think that the danger is much less in the former case, as sleep-walkers seem entirely free from the terror which commonly attends the attempting of any hazardous enterprise when awake; such as mounting to the roof of a house, climbing a steeple, &c. If suddenly awaked, however, while engaged in any of their hazardous actions, the danger is very great. 354 Dr Darwin considers somnambulism, not as a state of Reveries sleep or dreaming, but as a variety of reverie, carried to a morbid extent, so as to become a sort of epileptic or cataleptic paroxysm. In the state of reverie, according to Dr Darwin, the irritative motions occasioned by internal stimuli continue, those from the stimuli of external objects are either not produced at all, or are never succeeded by sensation or attention, unless they are at the same time excited by volition; the sensitive motions continue, and are kept consistent by the power of volition; the voluntary and associate motions continue undisturbed. He considers reverie as an effort of the * Zoonomind to relieve some painful sensation, whence it is al- mia, vol. i. $19. lied to convulsion and insanity *. 355 The torpor that takes place in many animals during Torpor of winter, appears to be so nearly allied to sleep, that we animals. shall consider it in this chapter. A great variety of animals of almost every class, retire during the cold of winter, to the recesses of caverns, holes in old walls, hollow trees, or below the, earth, where they remain in apparently a lifeless state till the return of spring rouses them from their trance. We shall here enumerate the different animals that have been known to undergo this state of hibernation. 356 Bats, especially the vespertilio murinus, auritus, and Hibernatv. noctula (see MAMMALIA, N° 39.); bears, especially ing mam the brown and the polar bear, and the badger; the hedge- malia hog, (crinaceus Europeus); several species of the mouse and rat tribe, but more especially the hamster (mus cricetus), the marmots, especially the arctomys marmota, (see MAMMALIA, N° 124.); the dormouse (myoxus muscardinus). Sheep appear capable of living for a considerable time in a torpid state, as they have been known to remain alive for several weeks, buried under the snow. 357 It does not appear that birds in general are capable of Hibernaundergoing this state of existence; but the instances oftion of swallows that have been found in this state in old walls birds; and hollow trees, and even, as some affirm, below water, and have recovered life and activity on being exposed to gradual warmth, are too well authenticated to admit a doubt, that these at least sometimes hibernate. 358 Most reptiles and serpents pass the winter in a state of of reptiles hibernation; but this is more particularly the case with and serthe land tortoise (testudo græca) see ERPETOLOGY, p. 271.; frogs, and those lizards which inhabit cold cli mates. pents; 359 * Reeve It is not certainly known whether many species of fish of fishes; become torpid in winter; but there is no doubt that se- Dis. Inaug. veral of them are susceptible of this state; and we are de Animatold that in North America, especially about Hudson's libus Hie bay, mesopitis,~, p.10. Of Sleep bay, fishes are not unfrequently found included within and Torpor a body of ice, and when exposed to gentle heat, have recovered life and motion. .60 Of insects. 361 Of man. 362 Principal phenomena of hibernation. 363 Suspended animation of some animals. It will appear extraordinary that we should place man among the hibernating animals; and yet there seems little doubt, that even he is capable of having his life suspended for a considerable time, when exposed to those causes which bring about the torpidity of those animals that we have already mentioned. We are told of a woman, who, in February 1789, remained eight days buried in the snow, and still recovered; and the case of the three women who remained for 37 days in a stable at Bergamoletto, that had been overwhelmed by an avalanche, or snow heap, with no other sustenance than the milk of a half-starved she goat, is well known. These instances, added to others of persons who have passed several weeks in a state of almost uninterrupted sleep, tend to prove that man himself may, under certain circumstances, continue in a torpid state. During this state of torpidity, the animals scarcely appear to live; sensation seems altogether lost; their irritability is so much diminished, that they may be cut, torn, or even broken to pieces, without expressing any mark of feeling, or giving any sign of motion; digestion seems entirely suspended; the secretions and excretions are discontinued. Some of the functions, however, are carried on. Respiration and circulation, though very languid, and sometimes scarcely perceptible, appear to go on in a degree sufficient to preserve the existence of the animal; and the action of the absorbents seems to be very little diminished, as appears from the gradual absorption of the fat. If the animal is taken from its place of confinement, and exposed to a gentle heat, it gradually recovers all its faculties; but if carried back to its cell, it relapses into the state of torpidity. The long suspension of animation, of which several animals are susceptible, appears still more extraordinary than the torpidity above described. The common hair worm (gordius aquaticus) may, when dried, be preserved for an indefinite length of time, and when put into water, gradually recovers its usual activity of motion. See HELMINTHOLOGY, N° 32. One of the most remarkable cases of this suspended animation is that related of the garden snail, of which the following curious account has been given in the Philosophical Transactions for 1774. Mr Stuckey Simon, a merchant in Dublin, whose father, a fellow of the Royal Society, and a lover of natural history, left to him a small collection of fossils and other curiosities, had amongst them the shells of some snails. About 15 years after his father's death (in whose possession they were many years), he by chance gave to his son, a child about 10 years old, some of these shells to play with. The boy put them in a flower-pot, which he filled with water, and the next day into a bason. Having occasion to use this, Mr Simon observed that the animals had come out of their shells. He examined the child, who assured him that they were the same he had given him, and said he had also a few more, which he brought. Mr Simon put one of them into water, and in an hour and a half after observed that it had put out its horns and body, a which it moved but slowly, probably from weakness. Of Sleep Major Vallancy and Dr Span were afterwards present, and Torper. and saw one of these snails crawl out, the others being dead, most probably from their having remained some days in the water. days in the water. Dr Quin and Dr Rutty also examined the living snail several times, and were greatly pleased to see him come out of his solitary habitation after so many years confinement. Dr Macbride, and party of gentlemen at his house, were also witnesses of this surprising phenomenon. Dr Macbride has thus mentioned the circumstance: "After the shell had lain about ten minutes in a glass of water that had the cold barely taken off, the snail began to appear; and in five minutes more we perceived half the body pushed out from the cavity of the shell. We then removed it into a bason, that the snail might have more scope than it had in the glass; and here, in a very short time, we saw it get above the surface of the water, and crawl up towards the edge of the bason. While it was thus moving about, with its horns erect, a fly chanced to be hovering near, and, perceiving the snail, darted down upon it. The little animal instantly withdrew itself into the shell, but as quickly came forth again, when it found the enemy was gone off. We allowed it to wander about the bason for upwards of an hour, when we returned it into a wide-mouthed phial, wherein Mr Simon had lately been used to keep it. He was so obliging as to present me with this remarkable shell; and I observed, at twelve o'clock, as I was going to bed, that the snail was still in motion, but next morning I found it in a torpid state, sticking to the side of the glass." The still more extraordinary instances that have been related, on what many have considered authentic testimony, of toads having been found inclosed in the trunk of a large tree, or within a solid block of stone, appear almost incredible; and yet if we consider that M. Herissant preserved toads in a state of suspended animation for 18 months, in boxes covered with a thick coating of mortar (see ERPETOLOGY, p. 286.); that the snails mentioned in the above quotation, must have lain for at least 20 years; and that flies have been recovered after being immersed for many months in Madeira wine, it is difficult to say how long this suspended animation may not be continued. 364 Similar phenomena take place in the vegetable crea-Hibernstion. Most of those plants which survive one year, tion of shed their leaves on the approach of winter; and, dur-plants ing this season, the motion of the sap ceases, and they have all the appearance of dead shrubs. The herbaceous tribes even die down to the roots, which, being mostly of the bulbous kind, afford shelter to the surviving germ; and are hence called, by botanists, the hybernacula of plants. On return of spring, the plant shoots anew from its winter's retreat, and flourishes with its former strength and beauty. Some plants are even capable of having their vitality, or rather the exercise of all their functions, suspended, as in the gordius and the snail, for an indefinite length of time. Mosses have been kept in a dried state in a hortus siccus for many years, and have shown no sign of life, till they were moistened and exposed to air, light, and a moderate heat, when they have recovered all their powers, have erected their stems, shot forth new branches, and flourished as at first. "Such then appears to be the connection between the Of Seep functions of respiration and those of the brain. Now, and Toro". in animals rendered torpid from cold, there are many observations which lead us to believe, that the immobility of the nervous system depends much, and very directly too, on the state of respiration. Of Sleep It is almost impossible, in the present state of our phyand Torpor. siological knowledge, to give any rational theory of these phenomena. The torpor of animals has been attributed 365 to exhausted excitability, or exhausted sensorial power; to the effects of habit, and to the effect produced on the brain by suspended or diminished respiration. The last of these, though not quite satisfactory, appears to us the most probable hypothesis. It has been ably defended and illustrated by Dr George Kellie, in a paper in which he relates a remarkable case of torpor from cold. Theory of torpor. "The powers of voluntary motion and of sensation (says Dr Kellie), are known to depend immediately upon the conditions of the brain and nerves; if, therefore, we could discover in what manner these organs are affected by any of the preceding events, we should advance considerably towards the solution of the questions above stated. (Namely, What is the order of succession between the diminished irritability of the heart, in consequence of the abstraction of caloric, and the complete torpor of the voluntary muscles and of the organs of sense, aud how are the intervening effects connected 2) Were the inactivity of these organs the direct effect of their diminished temperature; did the torpor in no case hap pen, till the heat of the brain and nerves was reduced beneath the natural standard, there could be hardly ground for any farther inquiry. But, as it is not so, some other change, less direct, must have occurred, in consequence of the connection of the brain with, and its dependence upon, some other of the functions antecedently and more immediately affected; and this function I apprehend to be respiration, between which and the energies of the nervous system a very intimate connection is maintained, through the changes produced on the blood during the pulmonary circulation. This dependence of the brain upon the properties of the blood, maintained by respiration, is evinced by a great variety of observations. Whatever impedes the respiratory changes of the circulating fluid debilitates or destroys the powers of muscular motion, as the respiration of noxious gases, of reduced or rarefied atmosphere; while greater exertions of muscular powers call for, and give occasion to more frequent respiration, more rapid consumption of air, and greater changes of the blood; and the breathing of more effective gases, as of the nitrous oxide, increases the motive and sensitive powers of animals. That these effects depend immediately upon the properties of the blood, as modified by respiration, acting on the brain, has, I think, been proved by the experiments of Bichat, who, in a masterly manner, has traced the mutual connection and dependencies of the vital functions in his admirable Recherches Physiologiques sur la Vie et la Mort. The transfusion or injection of venous blood into the carotids induced asphyxia or death, the instant it reached the brain; an effect which did not follow the similar transfusion of arterial blood from the carotid of * Bichat, another*. By these experiments, and by several other observations, he has shewn, that the asphyxia which so ches, part ii. instantly follows impeded or suspended respiration is occasioned by the impression of dark, venous, unchanged blood upon the brain, and not, as has commonly been supposed, from this blood being incapable of stimulating the left side of the heart, which, on the contrary, continues to contract and to circulate the blood for some time after the voluntary functions are suspended; an observation confirmed also by Coleman and others. VOL. XVI. Part II. Recher art. 7. + + Mem. on Respira "In the perfect torpor of the hibernating amphibia, respiration is completely suspended, and the consequent changes produced on the blood by that function totally prevented. This, which appeared from a variety of observations on the winter quarters of such animals found imbedded in mud, incased in ice, or closed up in opercula of their own construction, for the occasion of excluding the air, has been amply confirmed by the pointed experiments of Spallanzani, lately published by Senebier t. "In every case of torpor from cold, where the respi-tion. ration falls short of this complete suspension, it is at least more or less impaired. How much the torpid state depends on this condition of the respiratory functions, farther appears from observing, that hibernating animals, even those not of the amphibious order, warned by the approach of winter, instinctively or industriously seek situations unfavourable to perfect respiration, where this function may be either inadequately or not at all performed, as by premature and involuntary interment under ground, in old walls, in mud at the bottom of lakes, &c. The instinct of these animals, too, has been finely imitated by experiment, illustrating at once the object of this instinct, and confirming the opinion here advanced of its tendency. Thus the dormant hamster was found to regain and preserve its activity, when freely exposed to a pure atmosphere, the temperature, at the same time, not exceeding that at which it had formerly become torpid, or at which it returned to that state when again secluded under ground ‡. These ‡ Buffon's observations seem conclusive on this point, and, with Nat. Hist. those already brought forward confirming the general by Smeilic, connection established between the properties of the p. 19 blood, as modified by respiration, and the functions of the brain, render it, I think, highly probable, that the torpor of the voluntary powers, in the cases now under consideration, is the consequence of a limited and imperfect respiration, antecedently induced by diminished temperature. "Observation, indeed, is more deficient on this point with regard to the higher order of animals, and to men, who only occasionally become torpid from cold. Yet more than analogy, which is here very strong, leads me to believe that, even in these, the functions of respira tion are much and necessarily affected. The examples of cattle and of men remaining long torpid, deeply buried under snow, are pretty direct and convincing proofs of this. "If our induction from all these observations be admitted, we have the rudiments of a theory adequate to the explanation of the phenomena, in so far, at least, as the torpor of the voluntary powers is concerned. "From the suspended or imperfect respiration, those changes, by which the blood is fitted for maintaining the activity of the sensorial system, are interrupted; this imperfect blood circulating slowly through the brain directly impedes its functions, and so debilitates the excitability of the motive and sensitive organs, that they become torpid. This enunciation may seem hypothetical; but let the proofs of the intimate connection between the respirable and sensorial functions be weighed ; 3 U consider vol. vii. Of Steep consider also the interrupted respiration of hibernating and Torpor. and torpid animals, their instincts with regard to this, and the greater facility with which torpor is induced in a confined situation, which they naturally seek; and compare all these with the observations and experiments of Bichat on the effects of the immediate impression of venous blood upon the brain, and you will perceive a connected system, not entirely fanciful, a theory not without foundation and strength, and which appears to me at least to merit some attention *." *Edin. Med. and vo', i P. 308. For further particulars respecting the torpidity or hiSurg. Jour. bernation of animals, we refer the reader to Spallanzani's Tracts on Animals and Vegetables; White's Natural History of Selborne; Barton's Fragments of the Natural History of Pennsylvania; Pennant's Arctic Zoology; La Cèpede on Oviparous Quadrupeds, as translated by Kerr; Townson's Tracts on Natural History and Physiology, and the Inaugural Dissertation of Dr Reeve de Animalibus Hieme Sopitis, published at Edinburgh in 1803. 366 367 Gradual natural death. CHAP. XVI. Of Death. IN the article MAN, (N° 33. to the end) we have traced the progress of human life, from the cradle to the grave; and have briefly considered the phenomena and the consequences of natural death. In that article, and LONGEVITY, we have also stated the natural duration of human life, and the circumstances that tend to prolong our existence beyond the ordinary period. We shall not here enter again on any of these topics, except to give a more ample account of the gradual approaches of natural death, and shall then enumerate the causes which usually produce violent or accidental death, and mention the opinions of some of the best writers on the nature of death. Natural death is, in the present state of civilized soapproach of ciety, by no means a common occurrence. When it does take place, its approach is slow and gradual. He whose life terminates in consequence of advanced age, (to use the language of a celebrated French physiologist), dies in detail. His external functions successively cease to exert their action; all his senses are successively lost, or the ordinary causes of sensation pass over them without leaving their usual impressions. The sight becomes obscure, and at length the humours of the eye no longer transmit the rays of light; the ear receives only confused sounds, and frequently before death, is altogether insensible; the sense of touch, in consequence of the hardness and callousness of the cuticle, and the obliteration of many of the subcutaneous vessels, grows dull and uncertain; and all the parts depending on the skin show marks of weakness; the hair and the beard grow white, and a greater or less degree of baldness takes place; odours are no longer perceived, or they are perceived but faintly. The taste usually survives the rest of the senses; but that too, at last, grows equally obscure. The functions of the brain partake of the imbecility of the external senses. The imagination in particular becomes dull and often depraved; the memory no longer retains those occurrences which are every day taking place, though it recalls with increased relish and delight those of past times; the judgment becomes weak and wavering. From the universal agency exerted by the nervous system on all the animal functions, we must expect that 3 when the former is impaired, the latter will be propor- of Death. tionally enfeebled. The faculties of locomotion and of speech are commonly the first of these that fail; the body totters at every step, the voice grows weak, and the tongue faulters. The motion of the limbs is difficult and painful, and hence is but seldom willingly exerted. Not so with the vocal organs, though the impediments to utterance are evident and painful to his hearers, the old man himself seems scarcely to attend to them, but talks with proverbial garrulity, and especially delights in recounting the scenes and actions of his youth. While the external functions, and those of the brain, are thus gradually impaired; the internal, or what are commonly called the vital and natural functions, as digestion, absorption, circulation, respiration, and secretion, proceed with but little derangement. The circulation and respiration are indeed slower than before, and the appetite is in general less keen and returns less frequently; but the digestive powers of the gastric fluids remain in full vigour, and even after death has taken place, are exerted on the coats of the stomach; absorption is also very active, and nutrition, at least in many parts of the body, is sufficiently evident. At length, however, all these functions lose their powers; digestion languishes; the secretions no longer take place; the circulation especially in the minute vessels, becomes obscure, and being deprived of the tonic powers by which it was carried on, gradually ceases altogether; the heart no longer propels the blood from its ventricles; and the circulation + See through the lungs being thus arrested, these organs cherche cease to take in air, make their last expiration, and Physiol thus the natural life of man is terminated +. Bichat Re part i 368 Accidental or violent Accidental death takes place in one of the two fol. art. 10. lowing ways; either suddenly, in consequence of some great disturbance produced in the animal economy, as when a man is cut off by a sudden stroke of apoplexy, death. violent hæmorrhage, asphyxia, &c. or by slow and gradual steps, in consequence of some less violent but still fatal disease. In the former case, it is sudden or violent death; in the latter lingering death. Violent death may take place first, either in the brain, the lungs, or the heart; but when the action of one of these organs ceases, that of the others soon terminates. The entire cessation of life seems, however, to be more sudden in the two latter cases, and most of all in the last; when the heart is wounded or ruptured, the animal dies instantly; when the lungs are rendered inac tive in consequence of suffocation, the animal may live for several minutes, or for an hour or two; but when the brain is overwhelmed, he may survive for hours or even days. Thus it sometimes happens, in cases of apoplexy, that the patient lies motionless, speechless, and quite insensible to external stimuli, while the circulation and respiration continue, impeded indeed, but not destroyed, for a considerable time, though life, as appears from the event, be in a state of irrecoverable declension. We shall presently show how these circumstances have been explained. 369 The usual signs of approaching death are, a very Signs of ap quick and small pulse, scarcely distinguishable, and com- death. monly intermitting; coldness, and generally clammy sweats about the extremities; a "lack lustre" eye, sunk in features, want of expression about the countenance, and a prominence of the bones of the face, with a corresponding hollowness, in the cheeks, orbits, and especially |