III Natural Death Amongst Human Beings
Natural death in the aged—Analogy of natural death and sleep—Theories of sleep—Ponogenes—The instinct of sleep—The instinct of natural death—Replies to critics—Agreeable sensation at the approach of death
The death of old people, which has often been described as natural death, is in most cases due to infectious diseases, particularly pneumonia (which is extremely dangerous) or to attacks of apoplexy. True natural death must be very rare in the human race. Demange91 has described it as follows:—“Arrived at extreme old age, and still preserving the last flickers of an expiring intelligence, the old man feels weakness gaining on him from day to day. His limbs refuse to obey his will, the skin becomes insensitive, dry, and cold; the extremities lose their warmth; the face is thin; the eyes hollow and the sight weak; speech dies out on his lips which remain open; life quits the old man from the circumference towards the centre; breathing grows laboured, and at last the heart stops beating. The old man passes away quietly, seeming to fall asleep for the last time.” Such is the course of what properly speaking is natural death.
The natural death of human beings cannot be regarded as due to exhaustion from reproduction or from inanition, as in the case of Monstrilla. It is much more likely that it is due to an auto-intoxication of the organism. The close analogy between natural death and sleep supports this view, as it is very probable that sleep is due to poisoning by the products of organic activity.
It is more than fifty years since sleep was explained as the result of auto-intoxication. Obersteiner, Binz, Preyer, and Errera are among the competent men of science who have taken this view. The first two attributed sleep to an accumulation in the brain of the products of exhaustion which are carried away by the blood during repose. The attempt has been made even to discover the nature of these narcotic substances. Some investigators think that an acid, produced during the activity of the organs, is stored up in quantities that cannot be tolerated. During sleep, the organism gets rid of this excess of acid.
Preyer92 tried to put the problem upon a more exact basis by the theory that the activity of all the organs gives rise to substances which he called ponogenes and which he regarded as producing the sensation of fatigue. According to him these substances accumulate during the waking hours, and are destroyed by oxidation during sleep. Preyer thinks that lactic acid is the most important of the ponogenes, and lays stress on its narcotic effect. If his theory were correct, there would be a remarkable analogy between the auto-intoxication by lactic acid in the cases of man and animals, and the case of bacteria which produce the same acid and the fermenting activity of which is arrested as the acid accumulates. Just as sleep may be transformed to natural death, so also the arrest of lactic fermentation may be followed by the death of the bacteria which form the acid.
So far, however, there has been no confirmation of Preyer’s theory. Errera93 has brought forward against it another theory according to which the cause of sleep is not acid products, but certain alkaline substances described by M. Armand Gautier under the name of leucomaines. Gautier laid down that these substances act on the nervous centres and produce fatigue and sleepiness. According to Errera they might very well be the cause of sleep, as that comes on at a time when there is the greatest accumulation of these leucomaines in the body. He thinks that their action in producing sleep is a direct intoxication of the nerve centres. During sleep they are removed, and the disturbance which was produced in the organism is arrested.
If it were possible to accept Errera’s theory, a kind of analogy could be established between sleep and natural death on the one hand, and the arrest of development and death of yeast grown in nitrogenous media on the other hand, because in the latter case the poisoning is produced by an alkaline salt of ammonia. It must be confessed, however, that the actual state of our knowledge does not allow of a definite view of the real mechanism of the sleep-producing intoxication. Our ideas regarding leucomaines in general are still incomplete, and, recently, one of them, adrenaline, the product of the supra-renal capsules, has been investigated. Adrenaline is an alkaloid94 which is produced in the supra-renal bodies and is discharged into the blood. It has the power of contracting arteries strongly, and has been used to control blood-pressure. When it is given in large quantities or in frequent doses, it acts as a true poison, whilst, in small doses, it produces anæmia of the organs and has a special influence on the nervous centres. Dr. Zeigan95 has shown that a milligramme of adrenaline, mixed with five grammes of normal salt solution injected into the brain of cats, produces a soporific action. “About a minute after the injection, the animal appears to be plunged into deep sleep which lasts from 30 to 50 minutes. During this time, the sensitiveness of the animal has completely ceased throughout the body, and for some time after that it is much decreased. When they awake the animals seem to have been drunk with sleep for some time.” Sleep is generally associated with anæmia of the brain, and as adrenaline can actually produce such anæmia, it might be supposed that this narcotic substance is the most important of the organic products which give rise to sleep. Against this hypothesis, however, some weight must be given to recent investigations on fatigue and its causes.
Each stage in the advance of knowledge has had its influence on the study of the interesting and complex problem of sleep. When it was thought that alkaloids (ptomaines) were of great importance in infectious diseases, it was attempted to explain sleep as due to the action of similar bodies. Now, when we believe that in such diseases the chief part is played by poisons of extremely complex chemical composition, the attempt is made to explain fatigue and sleep by similar bodies.
Weichardt96 has recently made the best known investigations in this direction. This young man maintains with ardour the view that during the activity of organs there is an accumulation of special materials which are neither organic acids nor leucomaines, but which are much more like the toxic products of pathogenic bacteria.
Weichardt made animals in his laboratory go through fatiguing movements for hours and then killed them. The extract from muscles of such animals had a powerful toxic effect when it was injected into normal animals, producing lassitude and sometimes death within 20 to 40 hours. As all attempts to determine the exact chemical nature of this fatigue-producing substance were baffled, it is impossible to get an exact account of it. Amongst its properties there is one of great interest. When it has passed into the circulation of normal animals in quantities insufficient to produce death, it excites the formation of an anti-toxin in the same way as a poison of diphtheria stimulates the production of a diphtheria anti-toxin.
When Weichardt injected into animals a mixture of the poison which produces fatigue with small doses of the serum antidote, no results followed. The neutralising effect of the antidote was apparent even when it was introduced by the mouth. Towards the end of his investigations, Weichardt supposed that it would be possible to obtain a material that would prevent fatigue.
Although it is still impossible to specify exactly the nature of the substances which accumulate during the activity of organs and which produce fatigue and sleep, it is becoming more and more probable that such substances exist, and that sleep is really an auto-intoxication of the organism. So far, such a theory has not been shaken by any argument. Recently M. E. Claparède,97 a psychologist of Geneva, has argued against the current theory of sleep. He thinks that it is contradicted by the fact that new-born infants sleep a great deal, whilst very old people sleep very little. This fact, however, can readily be explained by the greater sensibility of the nerve centres of infants, as shown with regard to many harmful agencies. The other objections of Claparède, such as the fact that sleepiness is induced by exercise in the open air, or that excess of sleep itself produces sleepiness, are not really incompatible with the theory of auto-intoxication. They are facts of secondary importance probably depending on some complication which the present state of our knowledge makes it difficult to indicate exactly. The insomnia of neurasthenia, which Claparède brings forward as another objection, can readily be explained as due to hyperæsthesia of the nervous tissues which lose part of their sensitiveness to poisons.
On the other hand, there are many well established facts in agreement with the theory of auto-intoxication. Leaving out of the question sleep induced by narcotics, I may mention in this connection the so-called “sleeping sickness.” It has been proved that this disease is caused by a microscopic parasite, the Trypanosoma gambiense of Dutton, which develops in the blood and spreads to the liquid of the membranes surrounding the central nervous system. One of the most typical symptoms of the advanced stages of this disease is continual drowsiness. “The drowsiness increases progressively, and the habitual attitude becomes characteristic; the head is bent on the breast; the eyelids are closed; in earlier stages the invalid can be aroused easily, but, after a time, incurable attacks of sleep overcome the patient in all circumstances, but especially after meals. These fits of sleepiness become longer and deeper, until they reach a comatose condition from which it is almost impossible to arouse the patient.”98 The total result of medical knowledge of this disease is that it is impossible to doubt that the sleepiness is due to intoxication produced by the poison of the trypanosome.
Claparède has opposed what he calls an “instinctive” theory to the toxic theory of sleep. According to this theory, sleep is the manifestation of an instinct “the object of which is to arrest activity; we do not sleep because we are intoxicated or exhausted, but to prevent ourselves from falling into such a condition.” However, in order to bring this narcotic instinct into play, certain conditions are necessary, one of which certainly would be the intoxication of the nerve centres. M. Claparède supposes that sleep is an active phenomenon, induced when waste matter begins to accumulate in the organism. “To bring about sleep, the nerve centres must be influenced by waste matter, and this influence can readily be regarded as a kind of intoxication.”
Hunger is an instinctive sensation as much as sleepiness, but it does not appear until our tissues are in a condition of exhaustion, the exact nature of which cannot as yet be indicated. There is no real contradiction between the toxic and instinctive theories of sleep. The two theories represent different sides of a special condition of the organism.
The analogy between sleep and natural death is in favour of the supposition that the latter, also, is due to an intoxication much more profound and serious than that which results in sleep. Therefore, as natural death in human beings has been studied only very superficially, it is impossible to do more than frame theories regarding it.
It would be natural if, just as in sleep there is an instinctive desire for rest, so also the natural death of man were preceded by an instinctive wish for it. As I have already discussed this subject in the “Nature of Man” (chap. xi) I need not deal with it at length here. I should like, however, to add some information which I have recently obtained.
The most striking fact in favour of the existence of the instinct for natural death in man appears to me to have been related by Tokarsky in regard to an old woman. While Tokarsky was alive I asked one of his friends to obtain for me further details of this very interesting case. Unfortunately Tokarsky could add nothing to what he had already published in his article. I think that I have discovered the source of his information. In his famous book on the Physiology of Taste99 Brillat-Savarin relates as follows:—“A great-aunt of mine died at the age of 93. Although she had been confined to bed for some time her faculties were still well preserved, and the only evidence of her condition was the decrease in appetite and weakening of her voice. She had always been very friendly to me, and once when I was at her bedside, ready to tend her affectionately, although that did not hinder me from seeing her with the philosophical eye that I always turned on everything about me, ‘Is it you, my nephew?’ she said in her feeble voice. ‘Yes, Aunt, I am here at your service, and I think you will do very well to take a drop of this good old wine.’ ‘Give it me, my dear; I can always take a little wine.’ I made ready at once, and gently supporting her, gave her half a glass of my best wine. She brightened up at once, and turning on me her eyes which used to be so beautiful, said: ‘Thank you very much for this last kindness; if you ever reach my age you will find that one wants to die just as one wants to sleep.’ These were her last words, and in half an hour she fell into her last sleep.” The details make it certain that this was a case of the instinct of natural death. The instinct showed itself at an age not very great in the case of a woman who had preserved her mental faculties. Generally, however, it seems not to appear till much later, for old men usually exhibit a keen wish to live.
It is a well-known saying that the longer a man has lived the more he wishes to live. Charles Renouvier,100 a French philosopher who died a few years ago, has left a definite proof of the truth of the saying. When he was eighty-eight years old, and knew that he was dying, he recorded his impressions in his last days. Let me quote from what he wrote four days before his death. “I have no illusions about my condition; I know quite well that I am going to die, perhaps in a week, perhaps in a fortnight. And I have still so much to say on my subject.” “At my age I have no longer the right to hope: my days are numbered, and perhaps my hours. I must resign myself.” “I do not die without regrets. I regret that I cannot foresee in any way the fate of my views.” “And I am leaving the world before I have said my last word. A man always dies before he has finished his work, and that is the saddest of the sorrows of life.” “But that is not the whole trouble, when a man is old, very old, and accustomed to life, it is very difficult to die. I think that young men accept the idea of dying more easily, perhaps more willingly than old men. When one is more than eighty years old, one is cowardly and shrinks from death. And when one knows and can no longer doubt that death is coming near, deep bitterness falls on the soul.” “I have faced the question from all sides in the last few days; I turn the one idea over in my mind; I know that I am going to die, but I cannot persuade myself that I am going to die. It is not the philosopher in me that protests. The philosopher does not fear death; it is the old man. The old man has not the courage to submit, and yet I have to submit to the inevitable.”
I know a lady, a hundred and two years old, who is so oppressed by the idea of death, that those about her have to conceal from her the death of any of her acquaintances. Mde. Robineau, however, when between one hundred and four and one hundred and five years old, became quite indifferent to the close approach of her own death. She often expressed a wish for it, thinking herself useless in the world.
M. Yves Delage101 in an analysis of my “Nature of Man” doubted the existence of an instinct for death. “Animals,” said he, “cannot have the instinct for death, because they do not know of death. In their case, we must consider that what happens is an apathy tending to the abolition of the sense of self-preservation. In man, the knowledge of death implies that the indifference to its approach cannot be an instinct.” “There may be developed, at the end of life, a special state of mind which accepts death with indifference or with pleasure, but such a state cannot be designated as an instinct.” M. Delage, however, does not suggest what the state of mind in question is to be called. As the aunt of Brillat-Savarin compared her sensations just before death with the desire to sleep, and as this desire is an instinctive manifestation, I think that the cheerful acquiescence in death, exhibited by extremely old people, is also a kind of instinct. However, the important matter is that the sentiment exists, and not what we are to call it. M. Delage is far from denying its existence.
Dr. Cancalon,102 another of my critics, cannot admit the existence of an instinct of death, “because of the theory of evolution. Of what good would it have been, as M. Metchnikoff tells us that natural death is very rare; how could it have been transmitted, as it comes into existence long after the age of reproduction, and how could it have aided the survival of the species? If its existence were proved as the result of biological evolution, it would be a contradiction of adaptation and an argument in favour of final causes.” I cannot agree in any way with these opinions. In the first place, it is well known that men and animals have many harmful instincts that do not tend to the survival of the species. I need recall only the disharmonic instincts which I described in the “Nature of Man,” such as the anomalies of the sexual instinct, the instinct which drives parents to devour their young or which attracts insects to flames. The instinct of natural death is far from being harmful, and may even have many advantages. If men were convinced that the end of life were natural death accompanied by a special instinct like that of the need for sleep, one of the greatest sources of pessimism would disappear. Now pessimism is the cause of the voluntary death of a certain number of people and of many others refraining from reproduction. The instinct of natural death would contribute to the maintenance of the life of the individual and of the species. On the other hand, there is no difficulty in admitting the existence of instincts hostile to the preservation of the species, especially in the case of man, in whom individualism has reached its highest development. As man is the only animal with a definite notion of death, there is nothing extraordinary if it is in man that the instinctive wish for death develops. M. Cancalon denies the possibility that death can be pleasant, as it is the arrest of the physiological functions; but as sleep and syncope are often preceded by very pleasant sensations, why may not this also happen in natural death? Several facts prove it beyond dispute. It is even probable that the approach of natural death is one of the most pleasant sensations that can exist.
It is indubitable that in a large number of cases of death, the cessation of life is associated with very painful sensations. One has only to see the horror shown in the faces o£ many dying people to be convinced of this, but there are diseases and serious accidents in which the approach of death does not arouse sorrowful sensations. I myself, in a crisis of intermittent fever, in which the temperature descended in a very short time from about 106° Fahr. to below normal, experienced a feeling of extraordinary weakness, certainly like that at the approach of death. This sensation was much more pleasant than painful. In two cases of serious morphia poisoning, my sensations were more agreeable; I felt a pleasant weakness, associated with a sensation of lightness of the body, as if I were floating in the air.
Those who have noted the sensations of persons rescued from death have related similar facts. Prof. Heim, of Zurich, has described a fall in the mountains which nearly killed him, as well as several similar accidents to Alpine tourists. In all these cases he states that there was a sensation of pleasure.103 Dr. Sollier has told of a young woman addicted to morphia, who had been convinced that she was at the point of death. On recovering from a most serious attack of syncope, from which she was restored only by giving another dose of morphia, she cried: “I seem to come from far away; how happy I was!” Another of Dr. Sollier’s patients, a lady who had an attack of peritonitis from which she expected to die, felt herself “suffused with a feeling of well-being, or rather the absence of all pain.” In a third Case of Dr. Sollier, a young woman suffering from puerperal fever, feeling herself at the point of death, had a similar sensation “of physical well-being and of detachment from everything.”104
As a sensation of happiness occurs even in cases of pathological death, it is much more likely to occur in natural death. If natural death be preceded by the loss of the instinct of life and by the acquisition of a new instinct, it would be the best possible end compatible with the real organisation of human nature.
I do not pretend to give the reader a finished study on natural death. This chapter of Thanatology, the science of death, only opens the subject; but it is already apparent that study of the circumstances of natural death in plants, in the animal world, and in human beings, may give facts of the highest interest to science and humanity.