26 FOOT-NOTES TO EVOLUTION. 
surroundings in which they come into perfect adjust- 
ment. A partial adjustment must with time become a 
complete one, for the individuals not adapted will be 
exterminated in the struggle for life. 
Everywhere in Nature there is the closest adap- 
tation of life to its conditions. But this adaptation 
must come about through the survival 
How selection —_ of those organisms fittest to live under 
becomes adap- ie i : 
Sek way these conditions, while the unfit die out 
and leave no progeny. Thus, in the 
words of Professor Bergen, “ with much the same result 
as that which the farmer obtains by selecting his seed 
corn, the gardener by thinning out his beds, or the 
cattle-raiser by selling off his roughest calves for veal, 
Nature is at work on an inconceivably great scale, thin- 
ning out the least perfect individuals of each species.” 
But the thinning-out process is not the whole of 
“natural selection.” Other influences work in connec- 
tion with this. In the higher animals 
changes may be wrought by conscious 
or unconscious effort on the part of the 
creatures themselves, and the power to put forth such 
effort may be perpetuated by “natural selection.” Cer- 
tain organisms may carry their growth farther than their 
ancestors have done, so that the completed structures 
of their ancestors would be with them only a stage of 
development. And,as Professor Cope has shown, devel- 
opment may be hastened by the abridgment or omis- 
sion of useless stages. Thus the ultimate maturity of 
the animal may be carried to a degree of specialization 
beyond that of its ancestry. If this “accelerated de- 
velopment ” be for the gain of the species, “ natural 
selection ” will cause it to be retained. We may prop- 
erly include under “natural selection ” all those changes 
which come from the special use or disuse of any part 
Acceleration of 
development. 
