OTHER THEORIES OF SPECIES-FORMING. 209 



"ontogenetic selection," or of "coincident selection," is that 

 the personal selection, or individual survival, among indi- 

 viduals of a species does not necessarily depend solely upon 

 congenital variation but may, must, indeed, depend on any 

 ontogenetically acquired adaptations as well. As in many 

 cases these ontogenetic adaptations are considerable, they 

 will often carry individuals through very critical periods in 

 their lives. But the individuals showing these ontogenetic 

 adaptations in best degree will be those which actually pos- 

 sess certain slight congenital variations, especially of the 

 nervous system or coordinating nerve centres, "which lend 

 themselves to intelligent initiative, adaptive, or mechanical 

 modification during the lifetime of the creatures which have 

 them." The ontogenetic adaptations may occur regularly 

 in the lives of successive generations of individuals if the 

 environment remains fairly constant. During these suc- 

 cessive generations the congenital variations of brain, say, 

 which make the successful ontogenetic adaptations possible, 

 will by selection of the best ontogenetically varying individ- 

 uals be themselves selected, and the species thus gradually be 

 modified in a determinate direction. Also congenital varia- 

 tions of nearly the same nature as the ontogenetic variations, 

 or of a nature to supply the same need, will have time (that 

 is, more chance, because of the longer time and repeated 

 generations) to appear. In this case these advantageous 

 variations can be transmitted directly by heredity, and thus 

 a permanent adaptation be effected which will seem to be the 

 result of the inheritance of an acquired character (i. e., the 

 similar ontogenetic modifications) but which in reality is 

 only the normal inheritance of a congenital variation. 



In the language of all the sponsors for this theory there 

 seems to be a suggestion of the piling up or adding together 

 of congenital variations, not simply those of brain or other 

 control centre which make the ontogenetic modifications 

 possible, but also of these modifications themselves during the 



