MAN FROM THE FARTHEST PAST 
form, whose ancestry and the ancestry of the great apes 
separated from a common stock at some distant epoch 
which anthropologists incline to put as far back as the 
Miocene period. Still further back, in Oligocene or 
Eocene time, this stock separated, as it is supposed, from 
those of the gibbons and other Old World monkeys and 
from the small monkeys of South America. This hypothe- 
sis does not imply at all that man’s ancestors were like 
the present great apes. For the line of descent both of 
man and of the great apes has been subject to great evolu- 
tionary changes in these hundreds of thousands of years. 
We must therefore conceive that the supposed common 
ancestral stock was quite as different from the great apes 
of the present as from man. 
Speculating still further as to man’s descent, it may 
have come with that of other mammals through the am- 
phibians, and these by way of the fishes from the arthro- 
pods, where we lose all paleontological evidence in the long 
twilight of pre-Cambrian time. But the evidence from 
analogy found in the development of the human embryo 
leads us by the doctrine of recapitulation to assign simpler 
and simpler structures to this prepaleontological human 
ancestry, until in the beginning of life it originated from 
the cell itself. There scientific speculation commits the 
problem to religious faith. 
It is of surpassing interest to know what are the in- 
fluences which change the forms of life. From our knowl- 
edge of the structure of the cell, it seems clear that the 
almost infinitesimal chromosomes are the all-important 
elements which determine inheritance. Whatever of in- 
fluence the environment may exert upon a living creature 
can have no permanent effect on succeeding generations 
unless it modifies the chromosomes. 
Hence students of cytology have made many experi- 
ments to endeavor to change in some way the fundamental 
characters of the chromosomes. Without going far aside 
to note their work extensively, it will show something of 
[32] 
