34 PRESIDENTS ADDRESS. 
functions which are allotted to them. And when we consider the body: 
as a whole, we find that in every case the life of the aggregate consists 
of a definite cycle of changes which, after passing through the stages 
of growth and maturity, always leads to senescence, and finally: 
terminates in death. The only exception is in the reproductive cells, 
in which the processes of maturation and fertilisation result in 
rejuvenescence, so that instead of the usual downward change towards 
senescence, the fertilised ovum obtains a new lease of life, which is 
carried on into the new-formed organism. The latter again itself 
ultimately forms reproductive cells, and thus the life of the species 
is continued. It is only in the sense of its propagation in this way 
from one generation to another that we can speak of the indefinite 
continuance of life: we can only be immortal through our descendants ! 
The individuals of every species of animal appear to have 
pace a of 20 average duration of existence.?* Some species are 
life and pos- known the individuals of which live only for a few hours, 
sibility of its while others survive for a hundred years.2? In man 
— himself the average length of life would probably be greater 
than the three-score and ten years allotted to him by the Psalmist 
if we could eliminate the results of disease and accident; when these 
results are included it falls far short of that period. If the terms of 
life given in the purely mythological part of the Old Testament were . 
credible, man would in the early stages of his history have possessed 
a remarkable power of resisting age and disease. But, although many 
here present were brought up to believe in their literal yeracity, such 
records are no longer accepted even by the most orthodox of theolo- 
gians, and the uine hundred odd years with which Adam and his 
immediate descendants are credited, culminating in the nine hundred 
and sixty-nine of Methuselah, have been relegated, with the account of 
Creation and the Deluge, to their proper position in literature. When 
we come to the Hebrew Patriarchs, we notice a considerable diminu- 
tion to have taken place in what the insurance offices term the ‘ ex- 
pectation of life.’ Abraham is described as having lived only to 175 
years, Joseph and Joshua to 110, Moses to 120; even at that age 
‘his eye was not dim nor his natural force abated.’ We cannot say 
that under ideal conditions all these terms are impossible; indeed, 
Metchnikoff is disposed to regard them as probable; for great ages are 
still occasionally recorded, although it is doubtful if any as consider- 
able as these are ever substantiated. That the expectation of life was 
** This was regarded by Buffon as related to the period of growth, but the 
ratio is certainly not constant. The subject is discussed by Ray Lankester in an 
early work : On Comparative Longevity in Man and Animals, 1870. 
* The approximately regular periods of longevity of different species of 
animals furnishes a strong argument against the theory that the decay of old 
age is an accidental phenomenon, comparable with disease. 
