309 



given rise to the idea that the adult stages are 'pushed back into the 

 embryo.' Such a misconception easily arose from the loose language in 

 which the facts have often been expressed. Thus the embryogeny will be 

 gradually shortened by the omission of more and more of the superfluous 

 ancestral stages ; and it will tend finally to retain only such stages as 

 are necessary to the attainment of the adult form." Morgan and His, he 

 maintains, have confused morphology and physiology. "The recapitula- 

 tion theory has nothing to do with physiology ; it is purely a matter of 

 morphology." 



In conclusion Griggs says: "Taking all the evidence into considera- 

 tion, it seems to the writer that we are bound to conclude that though 

 organisms are subject to adaptations at any stage of their life cycles and 

 may gradually cut out superfluous stages, yet, except as some such ten- 

 dency has operated to change the heritage, the development of the indi- 

 vidual does recapitulate the history of the race * * * recapitulation 

 must take place if there is any force which tends to make offspring like 

 parent, if heredity is of any importance in moulding the forms of organ- 

 isms. On the other hand, if there is any variability of transmutation of 

 individuals in stages other than the adult end stages of the life cycles, 

 the recapitulation cannot be perfect, but must be marred at every stage 

 where secondary change has taken place." I shall return later to some 

 of the points raised by Griggs in the above statements. 



Another eminent worker, Dr. Eigenmann, says at the close of a paper 

 on the eyes of the blind vertebrates of North America (20) : "We have 

 seen in the preceding pages that the foundations of the eye [of Amohjop- 

 sls'] are normally laid, but that the superstructure instead of continuing 

 the plan with new material, completes it out of the material provided for 

 the foundations, and that in fact not even all of this (lens) material en- 

 ters into the structure of the adult eye. The development of the founda- 

 tions of the eye is phylogenic, the stages beyond the foundations are di- 

 rect." 



The third writer, Dr. Zeleny (64), in his paper on "Compensatory 

 Regulation." in a discussion of the development and regeneration of the 

 opercula in serpulids. says that the morphologic series is so complete as 

 to make sufficient ground for the conclusion that the opercula arose in 

 the course of phylogeny as modified branchia. The ontogenetic series, he 

 says, corresponds very closely icith the prooaole pliylogenctic series. 

 Speaking of the regeneratory development he says : "The course of re- 



