466 WM. E. KELLICOTT 



ard ('14) on the effects of radium radiation upon the eggs and 

 sperm of Nereis, has largely rendered untenable the suggestion 

 of Mall that the effects of such treatment are nutritional in 

 character. Packard concludes upon very clear evidence that 

 there are strong reasons for believing that the radium radia- 

 tions act indirectly upon both the chromatin and cytoplasm of 

 either or both germ cells or the zygote, b}^ bringing about in 

 these, destructive chemical processes. Development is thus ren- 

 dered abnormal both by the destruction of the normal chemical 

 and physical mechanism of early development, and also possibly 

 by the toxic presence of the abnormal substances thus formed and 

 present in the cleaving egg. That is, the abnormalities found in 

 later development may be referred to abnormal nuclear and cy- 

 toplasmic behavior during the cleavage processes, before the 

 specific germ-layer or tissue differentiations are inaugurated. 

 This clearly removes the results from the category of nutri- 

 tional effects and affords an explanation of the same general 

 character as that which I have suggested above, with this dif- 

 ference, however, that I am not inclined to stress the possibility 

 that the effects are due to the presence or absence of specific 

 chemical substances, but rather hold them to be due to unusual 

 combinations of differentiated materials both nuclear and cyto- 

 plasmic, in a word to a disturbance of the 'organization' of the 

 ovum or of certain parts of it; and this difference seems to me 

 of quite an essential character. 



How such results as those of Lewis ('09) and Spemann ('03, 

 '04) and some of Stockard's ('13 b) who caused cyclopia in Fun- 

 dulus and Amblystoma by the actual physical destruction or 

 even removal of the differentiated anterior end of the central 

 nervous system, can be interpreted as due to a nutritional effect 

 is even less clear than the possibihty of such an interpretation 

 of the effects of radium upon the spermatozoa previous to fer- 

 tilization. To compare and identify the cyclopia in Fundulus 

 resulting from such removals of already differentiating struc- 

 tures, with the cyclopia resulting from chemical treatment of 

 four to eight cell stages, involves the assumption that during 

 early cleavage in Fundulus there is already present some repre- 



