3oo THE POPULAR SCIENCE MONTHLY 



these I may mention the very interesting papers by Griggs on juvenile 

 kelps, Zeleny on the development and regeneration of serpulids, and 

 Eigenmann on the blind vertebrates of North America. 



Griggs especially criticizes the views of such critics of recapitula- 

 tion as His, who holds that the reason why ontogeny seems to recapitu- 

 late phylogeny is because the developing organism must from physiolog- 

 ical necessity pass from less to more complex stages, more or less 

 resembling ancestral forms; and the views of Morgan, who holds that 

 only embryonic stages of ancestors are repeated. This is the so-called 

 " Repetition Theory." To both of these critics Griggs objects that 

 they confuse physiology and morphology. " The recapitulation the- 

 ory," he says, " has nothing to do with physiology ; it is purely a matter 

 of morphology." 



On the first point, that the developmental stages are merely the 

 physiologically necessary steps in the development of the adult organ- 

 ism, the conclusions of Eigenmann and Zeleny are of especial interest. 

 Eigenmann shows that in the blind fish, Amblyopsis, the development 

 of the foundations of the eye is normal, and is phylogenic, while the 

 stages beyond the foundations are direct. Zeleny concludes that the 

 ontogenesis of the opercula of serpulids is phylogenic, and recapitulates 

 ancestral characters; but the regeneratory development of the organ is 

 direct, and may be very different from the ontogenetic development. 

 We may ask, therefore, if development takes a certain course only be- 

 cause that is the physiologically necessary way in which the individual 

 or the organ must develop, why should a condition of perfect blindness, 

 with almost total loss of all the eye structures, be attained only by the 

 round-about method of first developing the foundations of a normal 

 eye? Why, again, if there is any physiologically necessary course of 

 development, should the serpulid be able to regenerate the opercula in 

 a manner entirely different from their ontogenesis ? 



Hatschek, Hurst, Montgomery and others maintain that, if two 

 individuals differ in the adult, they must also differ in the egg, and 

 consequently must be different at all stages between. From this thesis 

 they draw the conclusion that organisms can not recapitulate adult 

 ancestral characters, because any change in the adult stage of an indi- 

 vidual, causing it to be different from its parents, involves a change in 

 the entire ontogeny — " the entire row of cells " from the egg to the 

 adult. That there is some sort of change in the entire row of cells we 

 grant; but that this change necessarily affects the morphology of the 

 individual or of its organs, up to the adult stage, we do not grant. 

 We have here again a confusion of morphology and physiology. The 

 cell energies may indeed be changed; but unless a change in the cell 

 energies inevitably necessitates a change in the morphology of all the 

 cells or of all the organs which they compose, the argument of Mont- 

 gomery proves nothing. 



