THROUGH CUMULATIVE SEGREGATION. 223 
followed without separating those differently endowed, we shall 
have, in the very nature of such variation, a cause of segregation 
and of divergent evolution. Some slight variation in the di- 
gestive powers of a few individuals makes it possible for them to 
live exclusively on some abundant form of food, which the species 
has heretofore only occasionally tasted. In the pressure for 
food that arises in a crowded community these take up their 
permanent abode where the new form of food is most accessible, 
and thus separate themselves from the original form of the 
species. These similarly endowed forms will therefore breed 
together, and the offspring will, according to the law of Diver- 
gence through Segregation, be still better adapted to the new 
form of food. And this increasing adaptation, with increasing 
divergence, might continue for many generations, though every 
individual should come to maturity and propagate ; that is, though 
there were no enhancing of the effect through Diversity of 
Selection, or indeed through any other cause producing Intensive 
Segregation. And when different forms of Intension do arise, 
they may be entirely independent of change in the environment, 
the only change being in the forms or functions of the organism. 
In choosing a name for this form of Segregation I first thought 
of calling it Physiological or Functional Segregation. But such 
a name is, on closer examination, found to imply both too much 
and too little ; for on the one hand there is probably no form of 
segregation that is not in some way or in some degree due to 
physiological or functional causes, and on the other hand this 
special form of segregation is as dependent on psychological 
causes which guide the organism in finding and in adhering to 
the situation for which it is best fitted, as it is on the initial 
divergence of the more strictly physiological adaptations by 
which it is able to appropriate and assimilate the peculiar form 
of resource. In the case of freely moving animals, the psycho- 
logical guidance is an essential factor in the success of the in- 
dividual ; while in the case of plants and low types of animal life, 
the suitable situation is reached by a wide distribution of a vast 
number of seeds, spores, or germs, and the same situation is 
maintained by a loss of migrational power as soon as the germs 
begin to develop. In these lower organisms it is evident that 
the success of the individual must depend on its physiological 
rather than on its psychological adaptations ; and if an initial 
divergence of adaptations results in a slight difference in the kinds 
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