DISCRIMINATE AND INDISCRIMINATE ACTION. 135 



in such cases are liable to be of importance, through the original 

 average character of the species not being fully represented and 

 through the fact that this initial bias often leads to some new 

 form of selection, which continues to act with cumulative force 

 through subsequent generations. No single pair can exactly repro- 

 duce the average character of the species in all its aptitudes 

 and habitudes, and therefore the methods of dealing with the environ- 

 ment adopted by the descendants are liable to be different. 



(2) In isolation and partition there is less opportunity than in 

 selection and election for cumulative effects in each generation. 

 Moreover, in many of the cases, the isolation is indiscriminate till 

 divergent forms of selection cooperate. But it should be noted that 

 the isolation of a small number of the species is of frequent occurrence, 

 and the failure of these small groups to represent the average charac- 

 ter of the group or race either in habitudes or aptitudes introduces 

 slight divergences determining new forms of autonomic selection 

 which are of great importance in molding new types. And even 

 when large masses are indiscriminately isolated all selection pro- 

 ducing coordinations between the members of the separate groups 

 ceases ; and the probability is that in the course of many generations 

 divergent forms of selection will arise, through different methods of 

 coordination between members as well as through different methods of 

 dealing with the environment adopted by different isolated groups. 

 This probability rests not so much on the probability of a difference 

 in the average character of the two large sections as on the probability 

 that in one section some new habitude will arise that does not arise in 

 the other section. The importance of isolation in producing diver- 

 gence is seen not only in its being the absolute condition on which 

 divergent forms of selection become of avail in producing divergence, 

 but in the fact that the isolation of a few individuals often introduces 

 from the first a divergent form of autonomic selection, though the 

 environment is the same, and in the fact that the isolation of a large 

 section of a species opens the way for a similar divergence of selection, 

 though it may require many generations for the result to become 

 apparent. Moreover, discriminate isolation (as when different indus- 

 tries have led individuals to form intergenerating groups according to 

 their aptitudes), leads from the first to divergence in adaptations and 

 to the intensification of adaptations. 



The table on page 136 will be useful in enabling us to keep in mind 

 the importance of these distinctions when applied to some of these prin- 

 ciples. Discriminate survival, which is usually called selection, is of 

 such importance that many terms have been needed to present the 



