The Nature of Man: Studies in Optimistic Philosophy

So universal a symptom of old age is the invasion of the tissues by macrophags, that it must be regarded as of im- mense importance. In order, however, to determine more precisely the nature of the function fulfilled by these phago- cytes, it was necessary to select a specially favourable sub- ject of investigation My choice fell upon an examination into the causes of the hair turning white,* that being as a rule the first visible sign of approaching old age.

Hair, before it has lost its colour, is full of pigment scat- tered throughout the two layers of which each hair is composed. At a given moment, the cells of the central cylinder of a hair become active, and proceed to devour all the pigment within their reach. Once they are filled with coloured particbs, these cells, which are a variety of macrophag (generally called pigmentophags or more * " Annales de 1'Institut Pasteur/' p. 865. 1901. properly speaking chromophags), become migratory, and, quitting the hair, either find their way under the skin or leave the body (Fig. 16). Th colouring-matter of the hair is removed in this way by chromophags, leaving the hair colourless.

The process by which hair becomes white is of importance, because it shows that the activity of macrophags is a domi- nant factor in bringing about senile decay. The brittleness of old people's bones is probably due to a similar cause, i.e., to the absorption and de- struction of the frame- work brought about by macrophags invading the layers of bone. There is still much that remains unknown in this subject, which is well worthy of special research.

The activity acquired by macrophags during old age is closely connected with the phenomena that are characteristic of certain chronic com- plaints. Sclerosis in old persons belongs to the same cate- gory as organic sclerosis, which may be set up by various morbid influences. The analogy between senile decay of the kidneys and chronic nephritis, commonly called interstitial nephritis, is incontestable. The destruction of nervous cells FIG. 16. Hair about to become grey. Chromophags transporting the pigment granules.

through the agency of rracrophags, which we have already mentioned as occurring in old age, is equally a symptom of several diseases of the nervous centres, such as general paralysis of the insane. Arterial sclerosis in old persons is actually an inflammatory disease, similar to the inflammation of the arteries set up by other maladies. The similarity between senility and disease has long been recognised, and partly accounts for the repugnance we all experience at the approach of old age. In childhood and early youth people regard themselves as older than they really are, and long to be " grown-up," but having once arrived at man's estate, they do not wish to grow old. An instinctive feeling tells us that there is something abnormal in old age. It cannot be regarded as a part of healthy physiological function. No doubt, because old age is the inevitable lot of mankind, it may be termed normal, in the same fashion as we call the pains of childbirth normal, since few women escape them. In both cases, however, we have to deal with pathological rather than physiological conditions. Just as every effort is made to relieve the sufferings of a woman in labour, so it is natural to try to suppress the evils accompanying old age, but whereas in childbirth an anaesthetic affords relief, old age is a chronic malady, a remedy for which is much harder to find. \\e have seen that in old age a struggle takes place between the higher elements and the phagocytes, the end being usually a weakening in vitality of the former, while the activity of the latter is enormously increased. It would appear, arguing from this, that one means of fighting against old age. patho- logically speaking, would be to strengthen the higher ele- ments of the organism, and to weaken the aggressive capacities of the phagocytes. Let me at once warn the reader that this is not presented as a definite, but as a

possible solution of the problem, and is offered for con- sideration like many other hypotheses on scientific questions. The properties of cellulai elements are easily changed when subjected to various influences, and it is therefore not irra- tional to seek some means of strengthening the blood cor- puscles, nerve cells, liver cells, muscular fibres of the heart, and so forth. The task has become easier since the discovery of serums that have specific actions on the tissues.

In the third chapter I stated that serums were known which give precipitates only with the blood of man and of his near relatives the anthropoid apes. serum of this kind has a definite specific action. Serums may be prepared that dissolve only the red corpuscles of particular species of animals, and that are without action on the other organic elements. It has been found possible, even, to prepare a serum that arrests instantaneously the move- ments of human spermatozoa, and that is neutral to the similar cells of other animals.

These serums are all prepared in the same way. The cellular elements in question, spermatozoa or red corpuscles, cells of the liver or of the kidney, taken from one animal, are injected into an animal of another species. After several injections have been made, the serum of the animal operated on becomes active with respect to the cells intro- duced into its body. These serums were discovered by J. Bordet of the Pasteur Institute, but the results have been confirmed by investigators in other countries. The serums are specifically cytotoxic, that is to say, they poison particular kinds of cells.

Now it has been shown that such serums, employed in small doses, do not kill or dissolve the specific tissue ele- ments, but actually strengthen them.* Here the case is analogous with the action of poisons, such as digitalis, which kill in strong doses, but which in weak doses improve or strengthen the action of certain tissues. In accordance with this indication, experiment has shown that small doses of a serum which is capable of dissolving the red corpuscles of human blood, actually increase the number of those in the body of a patient treated by injections. In the same way, in the case of a serum large doses of which destroy the red corpuscles of a rabbit, small doses increase the number of these elements in the blood.

Here there seems to be a rational method by which we may strive to strengthen the higher elements of the human body, and so prevent them from growing old. The task, at first sight indeed, seems an easy one, only necessitating the injection of a horse (or other animal) with finely minced atoms of human organs, such as brain, heart, liver, kidney, &c., when serums could be drawn off in the course of a few weeks, capable of acting upon those organs. In reality the process would be a very difficult one to carry out, as human organs are rarely obtainable in a condition suitable for injecting into animals. Post mortems can only be legally made twenty-four hours after death, and there are many other obstacles in the way of removing organs from dead bodies. Even if all these difficulties were overcome, another difficulty that would present itself would be the experi- menting with various doses of cytotoxic serums of various strength. It is not therefore to be wondered at that the 3/8, 390, 402. 1900. The results described therein have been confirmed by Belonovsky (" Sur 1'Influence de 1'Injection de Diverses Doses de Serum Hemolytique sur le nombre des Elements du Sang." Saint Petersbourg, 1902), who has found that there is an increase in the amount of haemoglobin and of red-blood corpuscles in the blood of anaemic patients that have been treated with minute doses of haemolitic serum.

attempt to reinforce the higher elements of the human organism will require much time. If it be necessary to strengthen the higher elements (nervous, hepatic, renal, and cardiac cells), it is plain that they undergo a progressively weakening process. It would be of the highest importance to ascertain the cause of this, for the knowledge would be a guide to future action. The similarity between senile decay and the diseases entailing atrophy in the more important human organs suggests a similitude in cause. Scleroses 01 the brain, kidneys, and liver frequently originate in intoxication by poisons such as alcohol, lead, mercury, and so forth, or the disease may be induced by some virus the virus of syphilis being a common cause.

The immense importance of venereal disease as a male- volent factor in the phenomena of old age, is especially manifested in arterial sclerosis. According to the careful investigations of a Swedish doctor, Edgren,* published in his " Monograph on Arterial Sclerosis," one case in every five of this disease is caused by syphilis, and he shows that chronic alcoholism is an even more frequent cause (25 per cent.). These two factors when united are responsible for nearly half (45 per cent.) the cases of arterial sclerosis that occur. Syphilitic virus and alcohol act as poises which bring about first degeneration and brittleness of the arterial walls, and eventually a weakening of the higher elements of the organism. The phagocytes, being cells of an inferior order, are less sensitive to these poisons, which accounts for their victory over the poisoned elements.

Rheumatism, gout, and infectious diseases only play a secondary part in setting up arlerial sclerosis. Edgren asserts, as the result of very careful calculation, that in * " Die Arteriosclerosis." Leipzig, 1898. nearly every fifth case he found it was impossible to account for the origin of arterial sclerosis. In the majority of cases the sufferers were elderly persons who, according to Edgren, " were afflicted with physiological sclerosis." * I take it that this sclerosis of unknown origin was by no means physiological but was pathological like that set up by syphilis or alcoholism. The question then arises whence comes the poison in such cases ? In syphilis there is a virus of a definite nature to deal with, which causes infection or poisoning, and brings about arterial sclerosis, general paralysis, and other serious ailments. Alcoholism is a poison arising from fermentation, excited by micro- scopical fungi related to true microbes. Instances of arterial sclerosis which are due neither to syphilis nor to alcohol poisoning nor to any other known cause, can only be accounted for as probably arising from poisoning set up by the mass of microbes congregated in the human intes- tines. Among these microbes there may be some that are harmless, and possibly even beneficial, but there are un- doubtedly a great number the presence of which is extremely prejudicial to health and life. It is impossible to enter into the details of such an important question, and a brief mention must suffice.

The human intestine contains an enormous quantity of bacteria, which, according to the recent investigations of Strassburger,! increase at the rate of 128,000,000,000,000 each day. These microbes, of which there are few in the digestive portion of the alimentary canal, are very numer- ous in the large intestines, i.e., in the lower part containing the waste material. The remains of undigested foods and the mucous secretions form a medium very favourable to the

growth of microbes. This bacterial flora constitutes a third part of the human excreta. It is very varied, and contains an immense number of different species, among which are bacilli, cocci, and many kinds of other bacteria, about which little is known. The distribution of this bacterial flora shows that it contributes nothing to the well-being of man, being scanty in the digestive portions of the body, and abundant in other parts of the gut. This fact alone suffices to refute the theory of those who attribute great functional importance to the intestinal flora. This theory originated principally from the fact that certain animals perish when brought up under special conditions protecting them from the presence of microbes. Schottelius * was the first to try the experiment of rearing chickens in a cage specially constructed for this purpose. The chickens hatched out, and lived for a few weeks: then, there being no microbes within them and only sterilised food being given, instead of increasing in weight, they became thin and showed signs of starvation. Schottelius supplied them with food from which bacteria were no longer excluded, upon which the chickens rallied, and soon became completely restored to health. Madame Metchnikoff f tried a similar experiment with tadpoles, which, when kept in vessels and fed upon bread containing the usual microbes, developed normally, but which, when reared under conditions entirely free from the presence of microbes, lived on for some months, but in a degenerate condition, their development being arrested.

On the other hand, Nuttall and Thierfelder | succeeded in keeping alive for several days new-born guinea-pigs, the alimentary canals of \vhich were free from microbes, anc which were fed only on absolutely sterilised milk and vegetable matter. Notwithstanding this complete absence of microbes the guinea-pigs developed well. As the two sets of experiments were conducted under conditions arranged so carefully that the chance of error was excluded, it is important to try to reconcile the apparently contradictory results. There is one point common to these three experiments, i.e., that they were all executed upon newly born creatures. Now it is well known that at birth the digestive juices are often very imperfectly secreted. In the case of the guinea-pigs, these juices sufficed in quantity for the digestion of the diet provided, whereas in the cases of the chickens and the tadpoles, the digestive juices were incapable of fulfilling their function satisfactorily, and the introduction of microbes endowed with considerable diges- tive capacity into the intestines compensated for the functional inefficiency of the gastric juices. In addition to the guinea-pigs experimented upon by Nuttall and Thier- felder, there may be mentioned a whole series of lower creatures such as the larvae of mites and other insects which are able to digest such indigestible material as wax and wool in spite of the total absence of microbes within their intestinal tubes. These experiments are corroborated by the established physiological fact that the gastric and pancreatic juices of mammals easily digest the most varied kinds of foods, even if treated so antiseptically as to ensure the total exclusion of microbes from the intestines.

I need not go further into this subject as the facts which I have cited suffice for my present purpose. The complete atrophy of the large intestines in the case of the woman referred to in chap. iv. proves not only that this portion of the alimentary canal is not indispensable to healthy life, but that life may be maintained in the absence of the flora of the large intestines. And this really is the centre of the problem. The useless bacterial flora may give rise to serious or fatal maladies. Wounds of the abdomen are really serious only when they penetrate the large intestines and so allow the entrance of bacteria from that region tc the peritoneal cavity. In such an event, the microbes rapidly multiply in the organism and produce a grave and frequently mortal illness. So long as the microbes remain within the intestines very few of them get into the circu- lation, and with these few the organism is able to cope. While most of the microbes are confined within the walls of the alimentary canal, the soluble excretions produced by them pass through into the lymph and blood. Quite a number of different facts establish this. Thus, for instance, it has been known for long that the urine of human beings and of animals contains a series of substances such as derivatives of phenol, indol, creosol, skatol, and so forth. In certain diseases the amount of these substances greatly increases. The stagnation of the contents of the intestines increases the amount of phenol and indol. Such facts and many others make it probable that these substances are the products of the bacterial flora of the intestines. They are absorbed by the intestinal wall, pass into the general circu- lation, and may give rise to various symptoms of a more or less serious nature.

Baumann, who has done much work on the subject, has brought together a series of arguments supporting the bacterial origin of the presence in the urine of the substances in question. Ewald, working from another point of view has obtained strong confirmation of Baumann's suggestions. He had the opportunity of making observations on a female patient, in whom, on account of a strangulated hernia, an intestinal fistula was established. Throughout the time during which the large intestines were inactive, the urine contained neither phenol nor indol. But as soon as the fistula was closed and communication with the large intestine had been re-established, phenol and indol reappeared in the excreta. Ewald formed the opinion, therefore, that these substances were products of the large intestine.

I need not weary the reader with more of the facts serving to show that the bacterial flora of the large intestines is the source of many poisons harmful to the body. It is among such substances that we must look for the slow poisons which, in the absence of syphilis or alcoholism, produce the arterial sclerosis of old age. In the fourth chapter I gave reasons to support my view that the large intestine in mammals had been developed because, by storing the products of digestion, it allowed them to run long distances without stopping, and so was an advantage in the struggle for existence. Moreover, the microbes which abound in the contents of the gut make it possible to use certain substances such as cellulose, that are difficult to digest. But these two advantages do not count in the case of the human race. Man does not secure his prey or escape from his enemies by the rapidity of his locomotion. The great development of his intel- lectual powers has given him advantages of another kind. Moreover, by the use of cooking and the cultivation of plants of high nutritive value, he is able to dispense with the digestion of cellulose.

There is another side to the picture. Ignorant of death and of old age, mammals have acquired the advantages of a large intestine at the expense of longevity. I have already stated that birds live longer than mammals. Birds are practically devoid of a large intestine, and maintain a bacterial flora very much poorer than that found in mammals. There is one exception to this rule, an exception of great importance. Ostriches and their allies, the largest known birds, are characterised by absence of the power of flight and by rapidity of terrestrial locomotion by which they escape their enemies. These are the only birds in which the large intestine is well-developed. The duration of life is much less in their case than in that of smaller birds, such as parrots, ravens, and swans. According to M. Riviere, who has been engaged in ostrich farming in Algeria, these large birds do not live more than thirty-five years. The mode of life, and the shorter duration of life, the huge development of the large intestines and the rich bacterial flora found therein make the ostriches much more like mammals than birds.

It is to be noticed that many birds in which the duration of life is long do not possess a caecum, the portion of the alimentary canal that contains most bacteria. Examina- tion of the intestinal contents of parrots shows that there exist in these birds very few microbes. A comparative study shows plainly that the existence of an abundant intestinal flora, useless for digestion, helps to shorten life by producing bacterial poisons which weaken the higher elements and strengthen the phagocytes.

The human race has inherited from its ancestors an enor- mous large intestine and conditions favourable to the life of bacteria. It has to endure the disadvantages of this heritage. On the other hand, the brain of man is very highly developed, and with the increase of intellectual power has come a consciousness of old age and death. Our strong will to live is opposed to the infirmities of age and the shortness of life. Here lies the greatest disharmony of the constitution of man.

If we desired to make the phenomena of old age physio- logical rather than pathological, it would be necessary tc reduce the evils arising from the presence of a large intestine. It is impossible, I may at once say, to wait for the operation of forces independent of the human will and that might lead to the suppression of an organ which has become useless. Man, guided by exact science, must strive to accelerate or anticipate such a result. In spite of the progress of surgery, I do not expect to find in our time that the large intestine will be removed by operation. Perhaps in the distant future such a proceeding will become normal. For the present it is more reasonable to attack the harmful microbes of the large intestine. In the varied flora of that region there exists microbes termed anaerobic, because they are able to live in the absence of free oxygen, obtaining what they require by the decomposition of organic matter. Such decomposition is attended by fermentations and putre- factions, and the production, of poisons, such as the alka- loids (ptomaines), fatty acids, and even true toxins.

In the human intestines under normal conditions, putre- faction occurs only very slightly, or does not occur at alL But in intestinal diseases of children and of adults, the microbes of putrefaction multiply abundantly and produce copious secretions which inflame the intestinal walls. To avoid these diseases of putrefaction in the case of infants, it has been suggested to use as food only sterilised milk or other foods quite free from microbes. This regimen has proved extremely successful.

In the investigation of the factors that hinder putrefac- tion, it has been noticed that milk putrefies with considerable difficulty, whereas meat, preserved under the same condi- tions, decomposes very readily. Investigators have attri- buted the stability of milk to the presence of casein or of milk-sugar. However, investigations recently made by Bienstock * and confirmed by Tissier and Martelly f have proved the existence of certain microbes that hinder the putrefaction of milk. These are in particular the microbes that sour milk, i.e., cause the formation of lactic acid, and which are antagonistic to the microbes of putrefaction. The latter multiply only in an alkaline medium. The lactic acid microbes produce large quantities of acid and so hinder the multiplication of the organisms of putrefaction. Putrefaction takes place rapidly, in spite of the presence of the lactic acid microbes, if there be added soda to macerations of meat or milk. Such facts explain how it is that lactic acid frequently stops some cases of diarrhoea, and why treatment with lactic acid is so useful in maladies associated with putrefaction of the intestinal contents. It makes intelli- gible, moreover, the medicinal value of fermented milk.

Rovighi,j an Italian physician, drank daily a litre and a half of kephir, a preparation made by subjecting milk to lactic acid and alcoholic fermentations. He found that in a few days the products of intestinal putrefaction in his urine either disappeared or were greatly reduced. It is plain, then, that the slow intoxications that weaken the resistance of the higher elements of the body and that strengthen the phagocytes may be arrested by the use of kephir, or still better of soured milk. The latter differs from kephir in that it contains no alcohol, and alcohol in course of time diminishes the vitality of some important cells in the body. The presence of a number of the lactic acid bacteria is inimical to the growth of the bacteria of putrefaction, and so is of great service to the organism.

But it is not enough merely to introduce useful microbes into the body. We must also prevent the entrance of " wild " microbes, many of which are harmful. Soil, espe- cially when it has been manured, contains large numbers of microbes, some of which are harmful. Bienstock found that the soil of the strawberry-beds in his garden contained the bacilli of tetanus. For three weeks he swallowed some of this soil, but found that the bacteria were destroyed in his intestines, which he attributed to the action of the normal bacterial inhabitants of the alimentary canal. It is pro- bable that if this arresting action were weakened the body would be infected by tetanus from spores of the tetanus microbe swallowed with earth or strawberries or green vegetables. Moreover, besides the organisms of tetanus, there are many other dangerous anaerobic bacteria in manured garden soil.

Obviously we should eat no raw food, but confine our diet rigidly to food that has been thoroughly cooked or sterilised. The exclusion of " wild " microbes and the introduction of beneficial microbes, such as those of lactic acid fermentation, must be of great service to health. I know of individuals who have derived great benefit from such a regimen. Science, even in its present imperfect condition, has many weapons by which to prevent or at least diminish the slow and chronic poisoning of the organism that leads eventually to the degeneration of the higher elements. When these elements are being destroyed by syphilis or alcoholism the struggle must be directed against these evils. It is long since we have known how to do this ; that success has not been greater is due to the carelessness of the people who are concerned.

to transform the " wild " population of the intestine into a cultured population, these are the means by which the pathological symptoms may be removed from old age, and by which, in all probability, the duration of the life of man may be considerably increased. If it be found impossible to eliminate all the harmful microbes from the flora of the intestines, those that are refractory may be rendered harmless by appropriate serums. We know already a serum that is specific against the microbe of botulism, an organism capable of exciting serious disturb- ance if it gain entrance to the alimentary canal.

Our inmost convictions assure us that life is too short, and since the remotest ages attempts have been made to prolong it. I need hardly mention the quest of the Middle \ges for an elixir of life, but many thoughtful men have occupied themselves with the problem. Descartes, who was deeply interested in the subject, believed himself to have found a mode of lengthening human life. Bacon published a tract on life and death, and in it gave advice as to how old age might be reached ; blood-letting and the use of saltpetre were parts of his specific.