The Recapitulation Theory in Biology 49 



development leads to a butterfly or a frog need not necessarily 

 be held to discredit these resemblances, and the force of Cumings' 

 contention receives a certain justification. 



That this position has limitations appears from one other 

 aspect of the study of development. Apparently it is possible 

 to over-emphasize the isolation of phases in ontogeny. For 

 although, as Morgan suggests, the organization of one period 

 need not be like the organization of another, still we are told 

 the essential unity of an animal is the central fact of the in- 

 ternal condition of its differentiation of structure, rather than 

 any mere interaction of the parts. This feature of development 

 has led to radical differences of opinion as to its import, and has 

 been interpreted in both vitalistic and mechanical terms. Aside 

 from the matter of interpretation the fact is admitted. The 

 following quotation from Morgan presents the situation as 

 viewed by one student of the facts: 



"The central problem for embryology is the determination 

 of what is the cause, or causes of differentiation. Our analysis 

 leads us to answer that it is the outcome of the organization; 

 but what is the organization?" 81 



The organization .... is a structure or arrangement of the 

 material basis of the organism, and to it are to be referred all 

 the fundamental changes in form, and perhaps of function as 

 well. . . .We know this organization at present from only a few 

 attributes that we ascribe to it, and are not in a position even 

 to picture to ourselves the arrangement that we suppose to 

 exist." 82 



The whole discussion of the section is thus shown to be full 

 of difficulty. We must conclude that the resemblances between 

 ontogenetic stages and ancestral forms are real and not factitious ; 

 still they are resemblances that show themselves among en- 

 tities in some fashion unique in every case. But this seems to 

 be true of all resemblances among organic beings. 



H. Biological Opinion Regarding Recapitulation. 



The situation in biology with reference to recapitulation 

 may be summed up as follows: 



1. Recapitulation as a record of phylogeny is denied in toto. 



2. The traditional view is still upheld. 



81 Regeneration, p. 258. 

 « Ibid., p. 288. 



