ENDONOMIC AND HETERONOMIC SELECTION. shy) 
habits, as was the case in the original home. ‘This is an illustration 
of what I call ‘‘habitudinal selection.’’ We shall next consider an 
illustration of aptitudinal selection, which will be gained by changing 
the illustration just given at one point. Instead of taking the two 
individuals which start the two colonies from those which for a genera- 
tion have been feeding on different kinds of trees, we must take them 
from two separate strains which have, for many generations, had 
their separate methods of feeding, so that not only their habitudes 
but their aptitudes must be somewhat different. Again, we may 
consider conditions that would produce what we might call ‘‘acct- 
dental selcction.” ‘This might occur if the two individuals starting 
the two colonies were from, the same strain and had both of them 
gained various experiences by feeding on different trees, so that their 
habits were not fixed. One of them we will suppose was brought by 
accident to a fine grove of candle-nut trees in the new district, and for 
a hundred years finds no cause to go elsewhere; while the other one, 
in another valley, is brought to a grove of what the Hawaiians call 
ohia trees, and there remains for an equal number of years. Is it not 
certain that the selection will be somewhat divergent; and to what 
determining cause shall we attribute the divergence if not to accidents 
that started these individuals of varied attainments in separate colo- 
nies, and in groves of different kinds of trees? As the valleys are 
near together and on the same side of the mountain range, the rain- 
fall and other features of climate must be essentially the same. If 
the creatures under consideration were insects endowed with digher 
powers for exploring the environment, I-recognize that accidents of 
the kind here suggested would have little or no effect in determining 
the forms of selection; for, in such cases, slight differences of aptitudes 
or habitudes would be sure to control the method of using the environ- 
ment. Moreover, such species would not fall into isolated groups 
through their occupying separate valleys. When an isolated individ- 
ual or pair deals with an environment possessing resources that are 
varied but familiar and easily explored, previous habitudes and apti- 
tudes are the chief factors controlling the methods of using the 
environment. If the power of using different resources is great 
and the power of exploration small, the method of using the envi- 
ronment may be determined by the kind of resources first reached 
on entering the district. 
Heteronomac selection is of two forms—natural selection, produced by 
conditions in the environment that are independent of any purpose to 
control the forms of survival, and artificial selection, which is deter- 
mined by more or less distinct purpose to control survival. If in the 
