THE ARGUMENTS FROM EMBRYOLOGY. 453 



which results from the divergence and re-divergence of 

 embryos, as they all unfold. On the hypothesis of evolution 

 this parallelism has a meaning — indicates that primordial 

 kinship of all organisms, and that progressive differentiation 

 of them, which the hypothesis alleges. But on any other 

 hypothesis the parallelism is meaningless ; or rather, it raises 

 a difficulty; since it implies either an effect without a cause 

 or a design without a purpose. 



§ 129. This conception of a tree, symbolizing the relation- 

 ships of types and a species derived from the same root, has 

 a concomitant conception. The implication is that each 

 organism, setting out from the simple nucleated cell, must in 

 the course of its development follow the line of the trunk, 

 some main branch, some sub-branch, some sub-sub-branch, 

 &c., of this embryological tree; and so on till it reaches that 

 ultimate twig representing the species of which it is a member. 

 It must in a general way go through the particular line of 

 forms which preceded it in all past times: there must be 

 what has been aptly called a " recapitulation " of the suc- 

 cessive ancestral structures. This, at least, is the conclusion 

 necessitated by the generalization we are considering under 

 its original crude form. 



Yon Baer lived in the days when the Development Hypo^ 

 thesis was mentioned only to be ridiculed, and he joined 

 in the ridicule. What he conceived to be the meaning of 

 these groupings of organisms and these relations among their 

 embryological histories, is not obvious. The only alternative 

 to the hypothesis of Evolution is the hypothesis of Special 

 Creation ; and as he did not accept the one it is inferable that 

 he accepted the other. But if he did this he must in the 

 first place have found no answer to the inquiry why organisms 

 specially created should have the embryological kinships he 

 described. And in the second place, after discovering that 

 his alleged law was traversed by many and various noncon- 

 formities, he would have been without any explanation of 



