IMPORTANCE OF EACH OF THE PRINCIPLES. 57 



generation, and so in intensifying the aptitudes. What, then, shall we 

 say of the segregate association of individuals according to their habi- 

 tudes, acquired by experimental initiation, individual repetition, social 

 imitation, and other methods of accommodation opening to the differ- 

 ent groups divergent methods of dealing with the environment ; and 

 what of the partition and election which cooperate in producing the 

 segregate association, and so in intensifying the acquired adjustments ? 

 Did the individuals of the primitive form or forms of life possess 

 powers that were in any way or in the least degree discriminative? 

 Had they any power to select that which is needed and to reject that 

 which is useless or detrimental? And when the environment became 

 somewhat complex, had the same species power to divide, one section 

 establishing close relations with one part of the environment and 

 another section with another part of the environment ? If the correct 

 answers to these questions are in the affirmative, then from early times 

 habitudinal segregation, in its two forms, partition and election, have 

 had an important influence on racial segregation, and, therefore, on the 

 evolution of innate aptitudes. 



In the production of segregated racial types isolation seems to be 

 the most essential of the four principles, for there can be no racial 

 segregation where there is no isolation, while there. may be cases of 

 segregation and divergence (at least for a number of generations) that 

 are not at all dependent on new methods of action of any one or more 

 of the other three principles. Such a case occurs when some peculiar 

 variation or mutation, being transported to a position where there is 

 no opportunity of crossing with other varieties, propagates its own 

 peculiarity for many generations, though exposed to the same external 

 conditions as the body of the species from which it has been separated. 

 If, however, the isolation is continued through a long series of genera- 

 tions, new forms of selection inevitably arise, and in time new forms 

 of acquired character resulting from new forms of activity and new 

 forms of direct stimulus from the environment; and in this way 

 the initial segregation produced by the isolation is intensified by 

 diverse forms of selection and by modifications resulting from estab- 

 lished habits. Moreover, the acquired characters may become the 

 active agency leading to new groupings of individuals, and in many 

 cases these new groupings introduce, or are accompanied by, group- 

 ings according to natural aptitudes and other innate endowments. 

 In other words, using the terms just indicated, we start with isolation, 

 which opens the way for divergent forms of selection, and the new 

 forms of selection lead to new forms of partition, and these lead to 

 new forms of isolation, thus establishing a circle of influences. Again, 



