CHAPTER X

INTRODUCTION TO THE SCIENTIFIC STUDY OF
OLD AGE

General account of old age-Theory of senile degeneration
amongst unicellular organisms Conjugation amongst
infusoria-Old age in birds and anthropoid apes-General
characters of senile degeneration-Sclerosis of the organs-
Phagocyte theory of senile degeneration-Destruction of
higher elements by macrophags-Mechanism of whitening
of the hair-Serums acting on cells (cytotoxins)—Sclerosis
of the arteries and its causation-Harm done by the
microbes of the alimentary canal-Intestinal putrefaction
and the modes of preventing it-Attempts to prolong
human life-Longevity in biblical times

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 problem, 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 treatment 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 Couddhôdana, 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, man 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 presents 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 hundreds-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 containing macerations of chopped hay or leaves. They multiply by means of division (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 zoologist, observed that the infusoria became 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 reproduction by simple division for many generations.

FIG. 12.

The periodical debility, which precedes conjugation is, *"Le Rajeunissement Kariogamique chez les Cillés," "Archives de Zoologie Expérimentale," 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 greater number of pathogenic organisms, conjugation has been very rarely observed. Even the largest kinds, such as, for instance, the anthrax bacillus, may be propagated for a long series of generations without the occurrence of conjugation.

Even in the case of the infusoria which by means of the process of conjugation can reproduce indefinitely, the preconjugal debility cannot be identified with the senile

degeneration of human beings, the FIG. 13. Conjugation of two Parahigher animals and trees. In all 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 infusoria 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 degeneration 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 rejuvenescence 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 degeneration 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, † 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 observing a South American parakeet (Chrysotis amazonica) which lived more than eighty-two years, longer than is usual even

* Biological Bulletin, vol. III., October 1902, p. 192; "Archiv. für Entwickelungsmechanik," vol. XV. p. 139.

f Gurney, “On the Comparative Ages to which Birds Live," The Ibis, January 1899, p. 19.