No. 627] 



ADAPTATION 



have to admit that differentiation means just this fact of 

 de novo formation. Otherwise it means nothing at all. 



We must, however, recognize certain essential differ- 

 ences between the development of a sea-urchin from an 

 egg and that of our world from the structureless spore 

 which was long ago liberated by its nebular parent. Let 

 us suppose that some experimental cosmogonist, using 

 the refined technique of a Morgan, Eoux or Driesch, had 

 skilfully removed about three quarters of our newly 

 formed globe, leaving the remainder to reconstruct itself 

 as best it could. The spherical shape would doubtless 

 have been quickly restored, but is it likely that there 

 would have formed in the ensuing ages just that same 

 arrangement of Europe, Asia, Africa, America and the 

 Islands of the Sea that we now find upon our maps I Un- 

 fortunately it is too late to perform this experiment, but 

 I think that most geologists would expect a much modi- 

 fied world as the result. Indeed, if the excision had bi^en 

 made after the mixture of molten substances had begun 

 to separate we should be perfectly certain that a quite 

 "abnormal" world would have been the outcome. All 

 this may be granted. 



Let us ask another question. Why is it that no inodcni 

 thinker22 has set forth a proforinalioii theory (.f idcial 

 evolution? It is only in accounting for individual tlevol- 

 opment that this has been thought necessary. Yet the 

 same paradox of de novo formation ^vould seem to con- 

 front us in both cases, while other essential points of re- 

 semblance betw^een pliylogeny and ontogeny have often 

 been pointed out. 



One difference, doubtless, is that every ])rocoss of pliy- 

 logeny is regarded as a unique thing, while ontogeny is 

 merely the nih. reduplication of a known type, the char- 

 acter of which can be stated in advance. Hence it is that 

 we are satisfied to resign the former process to the realm 

 of "chance," while the latter we come to look on as deter- 

 mined in advance. Another difference seems to be that 

 we look upon racial evolution as largely swayed by exter- 



