192 Orthoplasy 



method of development, in a way to modify that process 

 so soon as variations arose in lines of greater utility. This 

 again has greater emphasis and stronger force in the light 

 of intergenetic concurrence ; a point which, in the writer's 

 opinion, casts light upon the whole question of the relation 

 of development and evolution to one another. It may be 

 put as follows as a second point in this discussion. 



Second, when individuals acquire essential accommoda- 

 tions and modifications, these in so far mean the eradication 

 or subordination of congenital characters which stand in 

 their way or oppose them. If, then, concurrent evolution 

 is to follow, it will be by variations which include the essen- 

 tial neutralization or cancellation of such characters. Suc- 

 ceeding generations must, if this principle holds, depart in 

 these respects from strict recapitulation in all cases in 

 which the environment does not allow to the individual 

 all the stages in succession. Natural selection will seize 

 upon the individuals which vary concurrently, 1 that is, in 

 the direction of the abbreviations and modifications of the 

 genetic processes which are marked out first in the preceding 

 generations' ontogeny. 



From this certain general consequences flow, each of 

 which is illustrated by a large class of facts. 



(i) A generation of a species may exist in an early 

 simple form, an ancestral form, requiring little special 

 adaptation ; and afterwards, by some special mode of pro- 

 tection during later development, come unto the higher 

 adaptations of the later forms of the phyletic series. So 

 in the metamorphosis of many insects ; the larva or worm 



1 Using the phrase to include the group of coincident and correlated vari- 

 ations, of which organic selection, as shown in the following pages, may 

 make use. 



