DIVERGENT EVOLUTION THROUGH SEGREGATION. 313 
variations of both are nearly the same, but they will no longer be the 
members of one body between which the selecting process is carried 
out. On the contrary, if they occupy the same district each group 
will stand in the relation of environment to the other, modifying it 
and being modified by it, without mutually sharing in the same modi- 
fication. 
(2) Though one may exterminate the other, the change that comes 
to the successful group through the contest is not due to its superiority 
over the other, but to the superiority of some of its own members over 
others. 
(5) When any segregate form begins to arise we can not attribute its 
success to the advantage of se-generation, for the inter-generating forms 
are at the same time equally successful; wherefore it is not the success; 
but the separateness of the success, that is due to the se-generation. 
(4) The continuance of the descendants of a group in a special form 
will depend on its segregation, but this is a very different thing from 
the special success of its descendants. The preservation of a special 
kind of adaptation is never due to natural selection, which is the supe- 
rior success of the higher degrees of adaptation of every kind. 
(5) The power of migration, or any other power directly related to 
the environment, may be accumulated by natural selection, and after- 
ward lead to segregation, but, according to my method of judging, the 
continuous advantage of segregation over integration can never be 
shown, for both are equally essential in the economy of nature; and 
though one process may at one time predominate over the other, the 
comparative advantage of segregation, if there be such advantage, can 
not be the cause of the preservation of forms endowed with segregative 
qualities, for they will certainly be preserved as long as they are able 
to win a bare existence, which is often a lower grade of success than 
the one from which they are passing. 
(6) According to my view, instead of the accumulation of the segre- 
gative pre-potency depending on natural selection, the accumulation of 
divergent forms of natural selection depends on some form of segrega- 
tion. 
But if the accumulation of pre-potential segregation is not due to 
natural selection, how shall we explain it? It is I think due to the 
fact that those forms that have the most of this character are, through 
its action, caused to breed together. We have already seen, when 
considering seasonal and sexual segregation, that if segregation is 
directly produced by the instincts or physiological constitution of the 
organism, there is a tendency toward an increasing manifestation of 
the character in successive generations. Those that have but a slight 
degree of segregate pre-potency eventually coalesce, forming one 
‘ace, while those possessing the same character in a higher degree 
remain more distinet, and their descendents become still more segrega- 
gate and still more permanently divergent. As long as the segregate 
