298 THE POPULAR SCIENCE MONTHLY 



The paleontologist, more than any other naturalist, is concerned 

 with the product of these interactions, and to him, oftener than to 

 others, has come the question, Are these results species ? and, if so, what 

 are the criteria for the separation of species? The student of hard 

 structures appreciates the difficulty of drawing sharp lines, and one of 

 his most trying tasks is to satisfy the idiosyncrasies of his colleagues in 

 the making of species, subspecies, varieties, etc. The student of hard 

 parts finds transitional forms the rule, and he dare not grind them to 

 powder under his heel with the remark credited to Stimpson, that 

 " that is the proper way to dispose of those damned transitional forms." 



The philosophic paleontologist recognizes more readily than any one 

 else the truth of the dictum that nature knows only individuals, and 

 that species are special creations, called into being by the fiat of the 

 naturalist. He is concerned not so much with the origin of species as 

 with the origin of individuals; and while he makes use of the artificial 

 divisions called species, and sometimes finds his chief joy in multiplying 

 and subdividing them, he still recognizes their non-existence, and turns 

 to individuals. He may, perhaps, prefer to speak of mutations, mean- 

 ing individuals, nevertheless. 



But individuals are complex entities, and the paleontologist can not 

 investigate their genesis before he has thoroughly investigated the origin 

 of the parts composing it. As Professor Osborn has said, the paleo- 

 zoologist is concerned primarily with the origin of structures. He 

 alone is able to trace their development, for he is present at their birth, 

 he follows their whole history, and will be present also at their extinc- 

 tion, for the paleontologist alone is immortal. 



PALEONTOLOGY AND THE PtECAPITHLATIOX THEOEY 



By E. R. CUMINGS 



INDIANA UNIVERSITY 

 I 



BATHER once said that " If the embryologists had not forestalled 

 them, the paleontologists would have had to invent the theory 

 of recapitulation." This may be considered as a fair sample of the 

 attitude of at least the Hyatt school of paleontologists toward the theory. 

 It is doubtful if any paleontologist could be found who wholly rejects it. 

 In violent contrast with the more or less complete acceptance of 

 the theory by paleontologists, is the attitude of many embryologists 

 and zoologists. Montgomery and Hurst have perhaps put the case 

 against recapitulation more strongly than any one else. The former 

 says, for example, 



The method is wrong in principle, to compare an adult stage of one organism 

 with an immature stage of another. 



