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It has wisely entered into the views of Providence, that the existence of all organized bodies should be temporary. Yet we find considerable difference amongst them, in this respect. Whilst some of the lower classes of animals and vegetables are no sooner ushered into being than a process of decay appears to commence; others require the lapse of ages for their various developments and declensions; and, as a general principle, those, in which the attainment of growth has been slow, have the period of decrease proportionably protracted; whilst, where maturity has been rapidly attained, decay as rapidly supervenes.
The ages of man, we have seen, arc numerous and protracted. For a time, the parts of the frame, that are concerned in his development, unceasingly deposite the necessary particles by a process as beautiful and as systematic, as it is mysterious, until ultimately the growth, peculiar to the species and the individual, is attained. At this point, the preponderance, which previously existed in the action of the exhalants over the absorbents, appears to cease. is equality; but ere long, the exhalants fall off in their wonted activity; the fluids decrease in quantity; the solids become more rigid; and all those changes supervene that we have described as characterizing the decline of life, and the approach of that phenomenon which has now to be considered.
Death is the necessary, total, and permanent cessation of those functions, by which the presence of life is characterized. This cessation may happen at all ages, from accident or disease; a few only ceasing gradually to live by the effects of age alone. Hence a distinction has been made into that kind of death, which is produced by the gradual wear and tear of the organs, and that which cuts off the being prematurely from existence. The former has been termed, by some physiologists, senile or natural, the latter accidental. These differ considerably in their physiology; and will, therefore, require a distinct consideration.
1. Death from old age. The natural period of life is different in different individuals. It varies according to numerous appreciable and inappreciable circumstances;—the original constitution of the individual; the habits of life; the locality in which he may be situated, &c. Whilst some countries are remarkable for their longevity, others surprise us by the short period that is allotted for the natural duration of life.
Blumenbach asserts, that by an accurate examination of numerous bills of mortality, he has ascertained the fact, that a considerable proportion of Europeans reach their 84th year, but that few
exceed it; whilst, according to Foderé, in the insalubrious region of Brenne, in France, nature begins to retrograde, at from 20 to 30; and 50 years is the usual term of existence.
Haller noted one thousand cases of centenarians; sixty-two of from 110 to 120 years; twenty-nine of from 120 to 130; and fifteen who had attained from 130 to 140 years. Beyond this advanced age, examples of longevity are much more rare and less sufficiently attested; yet we have some well authenticated cases of the kind. Thomas Parr was born in 1635; married when at the age of 120; retained his vigour till 140; and died at the age of 152, from plethora -it was supposed—induced by change of diet. Harvey dissected him and found no appearance of decay in any organ. Henry Jenkins, who died in Yorkshire, in 1670, is an authentic instance of the greatest longevity on record. He lived 169 years.
It would not seem, that the natural period of life has differed much in postdiluvian periods. The Psalmist writes:
"The days of our years are threescore and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow, for it is soon cut off, and we fly away." And when Barzillai excused himself for not visiting the royal palace at Jerusalem, he observed to the king:
"I am this day fourscore years old, and can I discern between good and evil? can thy servant taste what I eat or what I drink? can I hear any more the voice of singing men or singing women? wherefore, then, should thy servant be yet a burden unto my lord the king?"
It is not easy to indicate the character of organization which is most conducive to longevity and to health. It has been supposed, however, and with some probability, that the state of the nervous system is greatly concerned; for the pathologist looks to this part of the frame as the commencement of many fatal maladies.
Generally, the aged individual sinks silently to death, in the manner we have described under decrepitude, totally unconscious of all that surrounds him. At other times, however, he preserves his sensorial powers to the last, and may be capable of locomotion; until, owing to some oppression of one or other of the vital functions during sleep, it becomes the sleep of death;—the elasticity of the organs being insufficient to throw off the oppression and resume their functions. At other times, a slight febrile irritation will be the prelude to dissolution. The great characteristic of this kind of death—as pointed out by Bichat in one of the best of his excellent productions-is, that animal life terminates long before organic life. Death takes place in detail;—the animal functions, which connect the aged with the objects around him being annihilated, long before those that are concerned in his nutrition. Death, in other words, takes place from the circumference towards
• Recherches physiologiques sur la vie et la mort.
the centre, whilst, in accidental or premature death, the annihilation of the functions begins in the centre and extends to the circumference. As vitality gradually recedes, in the aged, from the exterior, one of the great centres of vitality—brain, heart or lungs—stops for an instant. The powers are insufficient to restore the action, and total death necessarily ensues.
It has been an interesting inquiry with physiologists to determine the cause of death, thus naturally occurring. The opinions have been various, but such causes as affect the three great vital functions seem to be most entitled to consideration. These have been supposed to be, First, ossification of the arteries, occasioning an obstacle to the free circulation of blood in the parts; Secondly, ossification of the cartilages of the ribs, and diminution of the capillary system of the lungs, preventing sanguification; and Thirdly, shrivelling and gradual induration of the nervous system, ultimately rendering it unfit for innervation, &c. These are the physical circumstances or changes, which may give occasion to the final cessation of the vital phenomena, but, after all, the difficulty remains, and one that is insolvable,—to explain the cause why these changes themselves occur in the organs essential to vitality. We say it is insolvable, for until we have learned the nature of life, which seems far beyond our comprehension in the present state of our knowledge, it is obviously impracticable to understand the phenomena that arise from its gradual declension and final extinction.
It is not common, however, for death to occur in this quiet and gradual manner. Man is liable to numerous diseases, from the earliest to the latest period of existence, many of which are of an extremely fatal character. It was admitted by Sydenham, whose estimate cannot be regarded as more than an approximation, that two-thirds of mankind die of acute diseases; and that of the remaining one-third, two-thirds, or two-ninths of the whole, die of consumption, leaving, consequently, only one-ninth to perish from other chronic maladies, and from pure old age. How small, then, must be the number of those that expire from decrepitude simply? 2. Accidental death. This term has been used, by many physiologists, to include all kinds of death that befal mankind in the course of their career, and before the natural term; the cause consisting in the supervention of some accidental, organic lesion, which arrests the vital movements before they would cease of themselves. This kind of death differs essentially from that we have been considering. The individual is here, perhaps, in the full possession of all his faculties; his organs have been, previously, to all appearance, in the most favourable condition for the prolongation of vitality, and his death, instead of being natural, and unperceived in its approaches by the individual himself, is usually forced and violent.
Every species of sudden death commences by the interruption
of the circulation, respiration, or the action of the encephalon. One of these three functions first ceases, and the others die in succession. Each will demand a few remarks.
1. Death beginning in the heart.—When,—owing to fatal syncope, to wounds of the heart or great vessels, or to the rupture of an aneurism, the heart is struck with death, the cessation of the functions is speedy. Sensation and motion are lost; respiration is arrested, and death occurs,—if the cause of the cessation of the heart's action be suddenly and sufficiently applied,—almost instantaneously. The order, in which death takes place in the different organs, is as follows. The heart failing to propel its blood, the brain no longer receives the necessary impulse for the continuance of its functions; it therefore ceases to act; the consequence of this is the death of all those organs that receive their nervous influx from it; all voluntary motion is annihilated, as well as the action of the respiratory muscles. The mechanical phenomena of respiration are, therefore, arrested; and air is no longer received into the chest. From this cause, then, the chymical phenomena of respiration would cease, were they not previously rendered unnecessary by the cessation of the heart's action. The phenomena of nutrition and calorification,—the functions of the capillaries,yield last.
2. Death beginning in the brain.—In this case, owing to the loss of innervation,—as in severe injury done to the head, or in the worst cases of apoplexy,—the sensorial functions first cease, and the individual lies deprived of all sensation, volition, and mental or moral manifestation. Respiration becomes progressively more irregular and laborious, and ultimately ends. The order of death is here as follows:—the interruption of the brain's action destroys that of the voluntary and mixed muscles; the mechanical phenomena of respiration therefore cease, and then the chymical. This is followed by cessation of the heart's action, owing to the united loss of nervous influx from the brain,—and to the blood being no longer aerated in the lungs, but returned to it in a condition not adapted for the maintenance of its contractility. To the cessation of the heart's action succeeds the loss of the general circulation; and lastly, that of the functions of nutrition.
3. Death beginning in the lungs.—The action of the lungs may be destroyed in two ways: either the mechanical phenomena of respiration may first cease, as in hanging, strangulation, &c., where the air is prevented from reaching the lungs; or the chymical phenomena may be first arrested, as where air is breathed, which does not contain oxygen, but yet can be respired for a time.
In the first case, the order of death is as follows:--the mechanical phenomena cease; to this succeeds cessation of the chymical phenomena, owing to the supply of air being cut off; the blood is
now returned to the heart without being aerated, and therefore unfit for supporting that organ in action. It continues to beat, however, for a time; black blood is consequently sent to the brain and to every organ; the brain dies, and the other parts in succession. Where the chymical phenomena first cease, the suspension of the action of the brain follows for the cause already assigned; and the mechanical phenomena of respiration are not arrested, until the nervous influx is cut off by the death of that organ.
The immediate phenomena of death and the order of their succession are easily understood, where one of the great centres of vitality is suddenly destroyed, either from accident or disease, but where death does not follow immediately, and time is allowed for a series of morbid phenomena to be established, the problem becomes much more complicated. Some organ or structure is first deranged; and, owing to the intimate connexion, which we have elsewhere seen to exist between the various functions, general derangement or irritation follows, and the individual dies, worn out by such irritation, but without our being exactly able to understand on which of the great centres that dispense vitality, the malign influence has been exerted, or whether it may not have affected all equally.
In inflammation of the brain, heart, or lungs, we may presume, that the functions of these organs have been respectively annihilated by the diseased action; and that as such functions are essential to the existence of vitality, death may arise in the manner we have already described; but we frequently find the bowels affected with inflammation, or the peritoneum lining the interior of the abdomen; and the case, if neglected, is as surely attended with fatal consequences as the same morbid affection of the organs termed vital; and this in a space of time so short, as not to enable us to understand the nature of the mode of action of the lethiferous agent. But that it must exert its influence on one or more of the great centres of vitality is manifest. Perhaps in every case, the heart yields first, not suddenly but gradually; the brain failing to receive its due impulse, becomes progressively unfit for transmitting the nervous influence to the muscles; insensibility gradually supervenes, until it has attained such an extent, that no nervous influence is sent to the respiratory muscles, when cessation of their action naturally ensues. Of the nature, however, of the morbid condition of the heart, thus induced by disease, we are totally ignorant. It is fashionable to say, that death is produced by irritation, but this is merely concealing our deficiency of knowledge under a term, the explanation of the agency of which comprises the whole difficulty. Adelon thinks, that the brain generally gives way first in these cases; in consequence of which the respiration is disturbed, the lung becomes engorged, the respiration difficult, and death occurs as in a case of gradual asphyxia.