Ii6 EVOLUTION, GENETICS, AND EUGENICS 



genetic and cenogenetic phenomena must be sifted apart, an operation 

 which required more than one critical grain of salt. On what grounds 

 shall this critique be based ? Assuredly not by way of a vicious circle 

 on the ontogeny again; for if cenogenetic characters are present in one 

 case, who will guarantee that a second case, used for a comparison with 

 the first, does not likewise appear in cenogenetic disguise ? If it once 

 be admitted that not everything in development is palingenetic, that 

 not every ontogenetic fact can be accepted at its face value, so to 

 speak, it follows that nothing in ontogeny is immediately available 

 for the critique of embryonic development. The necessary critique 

 must be drawn from another source." 



These remarks of Gegenbaur's were called forth by the state of 

 wild speculation into which embryological work had fallen. As there 

 were no generally accepted canons of interpretation for the facts of 

 embryological development, different writers interpreted these facts 

 in the most divergent and contradictory manner, resulting in a chaotic 

 confusion, which led to a strong reaction against the whole method, 

 though there can be little doubt that this reaction has gone too far. 



"It must be evident to any candid observer, not only that the 

 embryological method is open to criticism, but that the whole fabric 

 of morphology, so far as it rests upon embryological evidence, stands 

 in urgent need of reconstruction. For twenty years embryological 

 research has been largely dominated by the recapitulation theory; 

 and unquestionably this theory has illuminated many dark places and 

 has solved many a perplexing problem that without its aid might have 

 remained a standing riddle to the pure anatomist. But while fully 

 recognizing the real and substantial fruits of that theory, we should not 

 close our eyes to the undeniable fact that it, like many another fruit- 

 ful theory, has been pushed beyond its legitimate limits. It is largely 

 to an overweening confidence in the validity of the embryological 

 evidence that we owe the vast number of the elaborate hypothetical 

 phylogenies which confront the modern student in such bewildering 

 confusion. The inquiries of such a student regarding the origin of any 

 of the great principal types of animals involve him in a labyrinth of 

 speculation and hypothesis in which he seeks in vain for conclusions 

 of even an approximate certainty." 



Many other equally vigorous and well-deserved criticisms of the 

 embryological method might be cited, but it should be emphasized that 

 these criticisms are all directed against the application of the method 

 to the solution of definite and concrete problems of descent and 



