The Nature of Man: Studies in Optimistic Philosophy

WHILE I cannot share the views of those who turn from science to seek truth and consolation in religion, it would be wrong to ignore or to be indifferent to the existence of that attitude. There are men who are tormented by the contradiction between the desire of life and the inevitability of death, and when these demand some solution of the pro- blem, it is unreasonable merely to say that they are too exacting and should learn contentment. If a man complains to his physician of uncontrollable hunger and thirst, he is not told that it is wrong to be so greedy, and that that fault could be mastered by strength of mind. The doctor carefully examines the patient and does what he can for the distressing symptoms, which, indeed, in this case are generally due to diabetes. Those who

hunger and thirst after eternal life, ought to be similarly treated by men of science whose duty it is to ameliorate their sufferings as much as possible. Science has undoubtedly gone far in the successful treat- ment of disease, both as regards prevention and cure, but it is powerless before those other evils from which Buddha implored his father to grant him exemption — old age and death. Science has attained to heights of knowledge undreamed of by Buddha's father, King Couddhodana, and yet it knows no more than he did with regard to the problem of old age and death. Like the king, science can but reply to its questioners : " You ask the impossible. I cannot help you ! "

Not only is no remedy for old age known to science, but little or nothing is known with regard to that period in the lives of men and animals. It was no easy task to compress an account of the present position of medicine within a few pages, the subject matter being overwhelming in quantity. With regard to old age it is quite the contrary, our knowledge being so limited that the subject may be dealt with in a few lines. With the advance of years, rnan and the higher animals undergo important modifications. They become weaker, the body shrinks, the hair whitens, and the teeth deacy, in fact, all the phenomena connected with senile decay manifest themselves.

At this period of life which overtakes various species of animals at different ages, the body becomes an easy prey to pernicious influences and diseases. The direct cause of death cannot always be determined, and is attributed to the general breaking up of the system which we call natural death. The first question which prereits itself to the scientific mind is whether this degeneration or senile decay is proper only to man and the higher animals, or is

common to all forms of life. We have all seen very old trees, the appearance of which proclaims their age. The trunk is decayed, the bark gnarled, the branches shrivelled, and the leaves scanty. Some kinds of trees live for hun- dreds— possibly thousands — of years, while others age with comparative rapidity. Senile decay is not unknown in the vegetable kingdom, and its presence is suspected even among creatures of very simple organisation belonging to the group of infusoria. These creatures may be reared with ease in vessels con- taining macerations of chopped hay or leaves. They multiply by means of divi- sion (Fig. 12), an operation which takes place at very short intervals, some of them dividing nearly every hour. Owing to this rapid multiplication the vessels soon become full of a mass of infusoria. M. Maupas,* a very distinguished zoolo- gist, observed that the infusoria became FIG. 12. Paramecium smaller and smaller after a number of about to divide in two. generations, exhausting themselves, as it were, and perishing unless two individuals succeed in uniting. This process of " conjugation " (Fig. 13), involves an exchange of portions of the bodies of the two creatures and brings about a complete rejuvenescence of the two individuals. After conjugation, a process essentially similar to the details of sexual fertilisation, the infusoria resume the normal appearance and again become capable of repro- duction by simple division for many generations. The periodical debility, which precedes conjugation is,

* " Le Rajeunissement Kariogamique chez les Cilles," " Archives de Zoologie Experimentale," 1899. according to Maupas, an instance of senile degeneration among infusoria. He has recognised its existence in the case of many species of the higher infusoria (Ciliata), but while this phenomenon has "been observed in the case of many other simple organisms, it cannot be set down as universal among microscopic beings. Among bacteria, a group that includes the greatei number of pathogenic organ- isms, conjugation has been very rarely observed. Even the largest kinds, such as, for instance, the anthrax bacillus, may be propa- gated for a long series of genera- tions without the occurrence of conjugation.

Even in the case of the infusoria which by means of the process of conjugation can reproduce indefi- nitely, the preconjugal debility cannot be identified with the senile degeneration of human beings, the FIG. 13. Conjugation of two Para- higher animals and trees. In all mecia (after Biuschli). these debility is the antecedent, not of conjugation and rejuvenescence, but of the end of life. Another important difference is that in the case of infu- soria the preconjugal debility does not occur in every individual, as is the case with the animals and plants which display real old age. In the infusoria an indefinite number of generations occur between the individuals that display debility and those that are ready for conjugation.

If, in spite -of these differences, we were to insist on the existence of an essential resemblance between senile degen- eration in man and preconjugal debility in infusoria, it would be enough to reflect on the result of applying to the case of man what is an infallible remedy in the case of the infusoria. For conjugation brings about a real rejuven- escence of the infusoria and a similar event in the case of man would only increase the debility. Moreover, according to recent investigations of Calkins,* infusoria, weakened by degeneration, may become young again not only by conjugating with their kind, but by the addition of bouillon or extract of brain to the medium in which they live.

Real old age is a phase of existence in which the natural forces abate never to be renewed. In animals, the life cycle of which is very definite, the signs of senile degenera- tion are not visible. Insects, in the adult condition, very often live only a short time, and die without displaying the slightest mark of age. In the case of lower vertebrates, old age is little known, and has few signs. On the other hand, mammals and birds display senile atrophy in a marked fashion.

Some species of birds live to a great age, longevity being more common than among mammals. Cases in which birds such as geese, swans, ravens, and some birds of prey, have been known to reach the age of fifty years, f are not uncommon, whereas such an event is very rare in the case of a mammal. Even small birds, such as canaries, may live as long as twenty years. Parrots are especially long-lived birds. Cockatoos have been known to reach the age of eighty years and more. I myself have had opportunities of observ- ing a South American parakeet (Chrysotis amazonica) which lived more than eighty- two years, longer than is usual even

t Gurney, " On the Comparative Ages to which Birds Live," The Ibis, January 1899, p. 19, \dth parrakeets. Several years before it died the bird showed unmistakable signs of old age. It became less lively, its plumage, although it did not whiten, lost much of its brightness, and the joints of the claws showed evidence of the presence of disease. In short, the parrakeet was obviously worn out and debilitated. Mammals show the signs of age even more plainly than do birds. A dog reveals old age by its slow movements, its white hairs, and worn teeth. The appearance of such an animal is never agreeable, while it is often dirty and ill- tempered. Brehm describes the old age of a dog as follows : " At twelve years of age a dog has grown old, and his gait and whole organisation show signs of age. The coat is no longer glossy ; the forehead and muzzle are grey, the teeth are blunted or have fallen out. The animal is lazy and apathetic. Many such dogs are dumb and blind. Dogs may live for twenty, six and twenty, or even thirty years, but such cases are most unusual."

As the dog is a domesticated animal, it might be argued that its old age, with its manifest signs of decrepitude, is the result of the artificial conditions of its life. To decide on this point it is necessary to examine an instance of old age in a wild animal. This presents certain difficulties since wild animals when old and feeble become an easy prey to carnivorous enemies. It will best serve our present purpose to consider such information as has been collected regarding the period of old age in anthropoid apes.

The natives of Borneo have observed " old orangs, which have not only lost their teeth, but being too feeble to climb, live on the fallen fruits and herbs." * Gorillas, according to Savage, turn grey in their old age, from which has arisen the erroneous view that there are two species of the gorilla. * Huxley, " Man's Place in Nature." In their wild state, monkeys, like ourselves, are subject in their old age to various distressing ailments. Senile degeneration, then, which is universally looked upon as one of the greatest evils of life, is by no means restricted to the human race. Old age, as portrayed in the Buddhist legend, referred to in chap, vi., is perhaps somewhat exaggerated, but this period of life is undoubtedly charac- terised by changes of such a nature as considerably to affect the happiness of the old. Buddha, being a pessimist, took too dark a view of this, but let us hear wrhat optimists have to say on the subject. Max Nordau, a doctor, a writer of books and a journalist, says : " Physically speak- ing, an old man presents an unpleasant picture of decrepi- tude to the casual observer. Morally speaking, he is a blind and pitiless egotist, having lost all interest in anything outside himself. Intellectually he becomes feeble-minded and narrow in his views, being governed by antiquated notions and prejudices, and incapable of grasping new ideas." *

It may be objected that I am here supporting my argu- ment by quoting from a writer who, in his capacity of clever journalist, rather forces the note. Let me therefore refer to what a learned physiologist said when addressing a serious audience assembled for the purpose of obtaining truth and information from his lips. After dealing in broad outline with the physical degeneracy caused by old age, Longet f draws the following mental picture : " The old feel that their task in life is accomplished, and believe them- selves to be universally grudged the space they occupy in the world. This renders them suspicious of all around them, and jealous of the young. Their craving for solitude

and the uncertainty of their tempers are due to the same cause. All old people are not like this, of course. The hearts of some remain youthful and beat strongly within their feeble frames, but, as a general rule, they are morose and a nuisance to themselves and others, excepting when they are surrounded by their children or grandchildren, who like to listen to them about the past, and who make excuses for the present. Thus the years speed onward, every round of the clock bringing the end nearer, and every hour adding a new wrinkle to their faces, some fresh weak- ness and some new regret. Their bodies . . . become decrepit ; their backbones, too weak to hold them upright, curve over and bend them downwards towards the earth."

There can be no doubt but that the period of old age is sad, and a thorough knowledge of it is necessary before it can be understood. Disease can only be successfully dealt with when the cause of its presence is known, and so it is with old age. Is it possible, one might ask, at the present stage of the world's knowledge, to define, with even approximate accu- racy, the characteristic features of senile decay ? The task is difficult, for although the subject is very important, few facts have been collected.

It is common knowledge that the flesh of old animals, used as food, is tough. An old fowl cannot be compared with a tender and juicy chicken. Organs such as the liver and kidneys are much harder in the case of old animals. The horny flesh of old animals is often compared with boot-leather. Although the comparison does not pretend to be scientific, it is far from being incorrect. Boot-leather is made from the hides of animals ; that is to say, of a very resistant material that is called " connective tissue," and which consists of a dense mass of fibres, mingled v/ith the

living elements or "connective tissue" cells. This tissue is very durable and so is employed for boots and shoes. The infiltration of any organ with connective tissue makes it tough and unpalatable. This hardening is called a sclerosis (of the liver, kidneys, &c.). In old age many organs exhibit this tendency to hardening or sclerotic degen- eration. The fact has been known for long, but its signi- ficance has been perceived more recently. Demange,* in his monograph on the organic changes associated with old age, states as follows : " Besides atrophy and degeneration of the parenchymatous elements,! there is to be observed a profound change in the framework of connective tissue, which serves to support the organs. In some cases the skeletal framework of an organ becomes more conspicuous, simply on account of the degeneration of the cells ; this is the condition usually present in the liver of aged persons. More often, however, the connective tissue receives some kind of stimulation, which, although it does not amount to inflammation, brings about an active growth and resulting sclerosis. According to the particular case, the hardening occurs in the form of isolated patches or strands, or affects the whole periphery or even the depths of the organ, and smothers the higher elements in its meshes, so producing a further degeneration. The cellular elements disappear gradually, connective tissue taking their place, and the change may be so profound, that as in the case of the pros- tate gland, the altered organ may actully transcend the normal size, partial or general atrophy, however, being more often the result."

* " Etude Clinique et anatomo-pathologique sur la Vieillesse." Paris, 1886. t The parenchymatous elements are the most important cells of the organs, i.e., of the liver, muscles, brain, &c. Sclerosis in old people sometimes takes the form of a hardening of the liver (cirrhosis of the liver) or of the kidneys (renal cirrhosis), but it is the arteries which are most com- monly affected by it, producing a symptom of degeneration which is called arterial sclerosis.

Cazalis long ago originated the oft-repeated aphorism : " A man is as old as his arteries," these vessels, by means of which the blood is distributed throughout the whole system, being of immense importance in the economy of the organism. When the connective tissue is so freely developed as to cause a hardening of the arteries, these, are hampered in the exercise of their function and become very brittle. According to Demange, all the special modifica- tions undergone by the body during the period of old age may be attributed to this atrophy of the arteries, but this theory is proved to be an exaggeration by the fact that post mortems on the aged frequently reveal the presence of little or no arterial sclerosis.

It might fairly be supposed that the hardening seen in many organs of the body during the period of old age is universal, and lends greater strength to the frame. The bones, which are separated from one another in youth, become welded together in old age owing to the calcareous deposits in the joints, and the ossification of the joints between the vertebra frequently causes the backbone to assume the appearance of a continuous bone, the greater part of the cartilage having become ossified. In spite of this, and as though for the purpose of proving how physi- cally full of contradictions is the period of old age, the human frame actually becomes lighter and the quantity of component mineral substances becomes less. This brings about a liability to fracture of the bones in old people. The fracture of the neck of the femur is a constant cause of

death in the aged, as occurred for instance in the case of Virchow, one of the most distinguished medical scientists of the nineteenth century. Is science, it may be asked, in a position to state precisely what are the principal modifications which occur in the tissues of old people ? At the International Congress of Medicine held at Berlin in 1890, a well-known German anatomist, Merkel,* attempted to reply to this question. Speaking of the tissues of old people, he tried to show that certain of these, such as the skin and the mucous mem- brane (the epithelial tissues), preserve their youthful cha- racters to the end, whereas others, such as the connective tissues, display profound changes, This essay was the first attempt to form a picture of the details of senile degeneration, but it did not reach any simple, general con- clusion.

Later on, I myself f tried to complete the work, and for the purpose made use of the published results of all the investigators who had studied senile degeneration. I gave a summary of my conclusions in the following words : " In senile atrophy the same condition is always present : the atrophy of the higher and specific cells of a tissue and their replacement by hypertrophied connective tissue." In the brain, the nerve-cells disappear ; that is to say, the cells which subserve the higher functions such as intellectuality, sensation, control of movement, and these are replaced by elements of a lower kind, in especial by neuroglcea, a kind of connective tissue of the brain. In the liver, the hepatic cells, of great importance to the nutrition of the organism; yield to connective tissue. In the kidneys, that tissue

invades and blocks the tubes by which the necessary process of eliminating soluble waste matter is accomplished. In the ovaries, the ova, the specific elements which serve to pro- pagate the race, are similarly eliminated and replaced by granular cells, a variety of connective tissue. In other words, a conflict takes place in old age between the higher elements and the simpler or primitive elements of the organism, and the conflict ends in the victory of the latter. This victory is signalised by a weakening of the intellect, by digestive troubles, and by lack of sufficient oxygen in the blood. The word conflict is not used metaphorically in this case. It is a veritable battle that rages in the innermost recesses of our beings. Distributed throughout every part of our bodies are certain cells which fulfil special functions of their own. They are capable of independent movement, and also of devouring all sorts of solid matter, a capacity which has gained them their name of phago- cytes or voracious cells. The function these phagocytes fulfil is a very important one, for it is they that congregate in vast numbers around microbes or other harmful intruders, in order to devour them. Effusions of blood and other elements, on penetrating to parts of the body where their presence is disadvantageous, are absorbed by these phago- cytes. In cases of apoplexy, where blood is shed into a part of the brain, setting up paralysis, the phagocytes cluster round the clot and devour the blood corpuscles it has encased. This absorption is a lengthy process, but by degrees, as the pressure of the effusion of blood is removed frcra the brain, and paralysis disappears, the health of the organism may become completely restored, recovery in such a case being due to the work of the phagocytes.

After childbirth, when the uterus presents the appearance of a great open wound clotted with blood, it is again the phago- cytes that clean it and re-establish the normal condition. It is plain, therefore, that the part played by these cells is beneficent. The phagocytes may be divided into small active phago- cytes, generally known as the microphags, and larger phagocytes called macrophags, which are sometimes active and sometimes still. The former, which are produced in the marrow of the bones, circulate freely in the blood, and occur as some of the white blood corpuscles, or leucocytes. They are distinguishable by their oval shape which facilitates their easy passage through the smaller blood-vessels, and allows of their accumulating in great numbers in the exu- dations that form around microbes. These exudations may be formed extremely rapidly, and so may arrest infection in the case of many diseases.

The absorption of extravasations of blood and the heal- ing of wounds are the work of the macrophags. In a general way, the microphags may be said to rid us of microbes, and the macrophags to heal mechanical injures, such as haemorrhages, wounds, and so forth. Macrophags possess a single unlobulated nucleus, and occur as white corpuscles in the blood, lymph, and exudations, or as the fixed cells in connective tissues, the spleen, and the lymphatic glands, &c.

The phagocytes are endowed with a sensitiveness of their own, and by means of a sense of smell or taste are able to recognise the nature of their surroundings. According to the impression made upon this sense, they approach the object which arouses it, exhibit indifference to it, or with- draw from its vicinity. V/hen, however, an infectious microbe finds its way into the body, the microphags are attracted by its excretions and swarm into the exudations surrounding it. The macrophags play a very important

part in bringing about senile decay. The atrophy ot the kidneys in old persons is attributable to their agency (Fig. 14). They accumulate in large quantities in these organs, cluster- ing round about the renal tubes which they ultimately cause to disappear. Having appropriated the place of the renal tubes, the macrophags proceed to form connective tissue, which thus takes the place of the normal renal tissue. A similar process occurs in the other organs that

FlG. 14. Section of a Renal Tubule, invaded by Macrophags, ftom the body of an old man of 90 years. w = macrophaET. (From a pre- paration made by Dr. Weinberg. ) FlG. 15. Cell from the brain of a woman 100 years old being devoured by ma- crophags. (From a pre- paration made by Dr. Philippe. ) degenerate in old age. In the brains of old persons and animals, for instance, it is known that a number of nervous cells are surrounded and devoured by macrophags (Fig. 15). Judging from the investigations mentioned above, I think I am justified in asserting that senile decay is mainly due to the destruction of the higher elements of the organism by macrophags. This conclusion has been confirmed by means of direct observation, which was the more necessary as it is contrary to the opinions of some biologists. Mari- nesco,* an authority upon everything connected with the nervous system, has disputed my theory, asserting that * Comptes Rendus de I Academic des Sciences, April 23, 1900.

the destruction of the specific elements in the nervous centres of old persons is not brought about through the agency of macrophags. In support of his theory, M. MarL nesco was good enough to send me a series of preparations from the spinal marrow of persons of very advanced years from which evidence of destruction by means of phagocytes or phagocytosis, was completely absent. I freely admit the absence of phagocytosis in M. Marinesco's preparations, but these were derived from the cells of spinal marrow, which is much less subject to the ravages of senile decay than is the brain. Even in the lower portions of the encephalon, senility and its parallel, phagocytosis, are uncommon, whereas in the brains of old persons, which are more generally affected by senile decay, the higher elements are clearly shown to undergo destruction by macrophags (Fig. 15). The same phenomenon may be observed in the case of parrots and dogs of advanced age, a'nd in other animals.