Cope. ] 208 [Dec. 15, 
ing of food. With will necessarily appears a power of choice, however 
limited in its lowest exhibitions, by the lack of suggestive metaphysical 
qualities, or the fewness of alternatives of action presented by surround- 
ing circumstances, to animals of low and simple organism. We can, 
however, believe that the presence of greater or less number of external 
facilities for action, characterize different situations on the earth’s sur- 
face, as well as that greater and less metaphysical capacity for perceiving 
and taking advantage of them, must exist in different individuals of 
every species of animal, however low, which possesses consciousness and 
will. -These qualities will, of course, influence effort and use to the ad- 
vantage of the animal, or the reverse. 
Effort and use have very various immediate stimuli to their exertion. 
Use of a part by an animal is either compulsory or optional. In either 
case, the use may be followed by an increase of nutrition under the influ- 
ence of reflex action or of direct volition. 
A compulsory use would naturally occur in new situations which take 
place apart from the control of the animal, where no alternatives are pre- 
sented. Such a case would arise in a submergence of land where land 
animals might be imprisoned on an island or in swamps surrounded by 
water, and compelled to assume a more or lessaquatic life. Another case 
which has also probably often occurred, would be when the enemies of a 
species should so increase as to compel a large number of the latter to 
combat who had previously escaped it. 
In these cases, the structure produced would be necessarily adaptive. 
But the effect would sometimes be to destroy or injure the animals (retard 
them) thus brought into new situations and compelled to an additional 
struggle for existence, as has, no doubt, been the case in geologic 
history. 
Direct compulsion would also exist where alternatives should be pre- 
sented by nature, but of which the animal would not be sufficiently intel- 
ligent to take advantage. 
Most situations in the struggle for existence, afford alternatives, and 
the most intelligent individuals of a species will take advantage of those 
most beneficial. Nevertheless, it is scarcely conceivable that any change 
or increase of effort, or use, could take place apart from compulsion de- 
rived from the relation of external circumstances, as a more or less remote 
cause. ‘ 
Preservation, with modifications, would most probably ensue when 
change of stimulus should oceur gradually, though change of structure 
might occur abruptly, under the law of expression points. 
Choice is influence not only by ¢ntelligence, but by the ¢magination and 
by the emotions. 
Intelligence is a conservative principle, and always will direct effort and 
use into lines which will be beneficial to its possessor. Here we have the 
source of the fittest—7. ¢., addition of parts by increase and location of 
* See origin of Genera, p. 38. 
