140 CLASSIFICATION OP THE FORMS OF THE PRINCIPLES. 



4 . Conditions Determining the Forms of Selection. 



The forms of selection depend on the following conditions (the 

 letters and numbers are those used in the tables on pages 138-139) : 



j. The relations in which individuals of the same group stand to 

 each other; that is, the reflexive conditions. First, the aptitudes (i. e., 

 instincts and other inherited powers), that shape these relations to 

 each other; second, the habitudes (i. e., habits and other acquired 

 powers), that shape their relation to each other; and, third, the 

 physical characters of the individuals, must be coordinated. 



k. The relations in which the group stands to the environment, that 

 is, the environal conditions (arising from the action and reaction be- 

 tween the group and its environment), must be harmonized. 



20. The conditions within the group that shape these relations to 

 the environment; that is, the endonomic conditions, being (56) the 

 habitudes, and (57) the aptitudes that enable the isolated group to 

 determine how it will use the environment, must be kept in the fullest 

 possible accord with these uses and with each other. 



21. Heteronomic conditions, (58) natural and (59) artificial; that is, 

 conditions in the environment that constitute a limit to the possible 

 methods of escape from destruction. Small colonies of Hawaiian 

 snails, of the same species, isolated in neighboring valleys, but occu- 

 pying the same species of trees and feeding in the same way, and all 

 exposed to the same enemies, it seems to me are probably subject to 

 the same forms of heteronomic environal selection. Any snail, 

 capable of living on several species of trees growing in thick, shady 

 groves, when brought to a valley where onlj' one species of such trees 

 is found, is subjected to heteronomic conditions, for but one method 

 of survival is open to it. But even under these conditions we find 

 divergence taking place in isolated groups. Shall we attribute such 

 divergence to diversity of selection or to the diversity presented in 

 the average character of the groups when first isolated? I believe 

 this latter explanation is the more reasonable. If each colony was 

 originated by a single snail, we know it is impossible that these original 

 progenitors of the different colonies should in every respect have 

 possessed the same characters. It is also impossible that the varia- 

 tions occurring in an isolated colony springing from a single pair 

 should be exactly the same variations, presented in exactly the same 

 proportions, as in the mother colony from which they were separated. 



The influences determining the forms of isolation, partition, and 

 election are also presented under the aspects of reflexive influences 

 and environal influences, and in constructing terms for the different 



