TEE PALEONTOLOGIC RECORD 299 



And again : 



Therefore we can only conclude that the embryogeny does not furnish any 

 recapitulation of the phylogeny, not even a recapitulation marred at occasional 

 points by secondary changes. 



Hurst is even more emphatic. He says : 



The ontogeny is not an epitome of the phylogeny, is not even a modified 

 or " falsified " epitome, is not a record, either perfect or imperfect of past 

 history, is not a recapitulation of evolution. 



It would seem as though two statements could scarcely be more 

 flatly contradictory than those of Bather and Hurst, just quoted. 

 Nevertheless, I venture to make the assertion that both parties to the 

 recapitulation controversy are right, for the simple reason that they are 

 not talking about the same thing. Grabau has called attention to this, 

 by implication, in one of his papers on gastropods. He states that the 

 recapitulation theory has been placed in an evil light by the habit of 

 embryologists of comparing embryonic stages with the adults of exist- 

 ing representatives of primitive types, and that they have commonly 

 neglected to compare the epembryonic stages with the adults of geolog- 

 ically older species. In other words, paleontologists have usually dealt, 

 in their comparisons, with epembryonic stages, and embryologists with 

 embryonic stages. 



There arises here a question of definition : does the biogenetic law 

 mean that the ontogeny is a recapitulation of the ph}dogeny, or does 

 it mean that the embryogeny is a recapitulation of the phylogeny? 

 If we take the general consensus of opinion, w T e shall find for the former 

 definition; and if we take the words of Haeckel, whose statement of 

 the law is the one usually quoted, we shall again find for the former 

 definition. 



It is certainly true, at any rate, that the epembryonic stages may 

 and do show recapitulation, even when the embryonic stages do not, or 

 when the embr}'ogeny is so obscured by secondary adaptations as to be 

 untrustworthy. There are many reasons why adaptations should occur 

 in infra-uterine or larval life to obscure the ancestral record. These 

 have often been stated and discussed, and I shall pass them with this 

 mere mention. That the record of remote ancestors, contained in the 

 embryogeny, may be lost or obscured, while the record of nearer ances- 

 tors, contained in the epembryogeny, is still clear and convincing, is 

 my contention; and I hold that this contention is substantiated by the 

 studies of a host of paleobiologists. 



While contrasting the views of biologists and paleobiologists, I do 

 not wish to create the impression that all of the former have turned 

 against the theory of recapitulation. Several recent studies of the 

 development of extant forms seem to afford very satisfactory evidence 

 that the theory is not wholly rejected in the house of its fathers. Of 



