26 



Morgan, one blastomerc killed in 2-cell 

 stage of Fiimiiilus. Result perfect em- 

 bryos 2-3 normal size. 



Wilson on eggs of Ampliioxus. 



2-cell stage, perfect blastulas gastrulas 



and nearly perfect larvae 1-2 size. 

 4-cell stage, less perfect larvae 1-4 size. 

 8-cell stage, imperfect blastulas. 



Wilson's arguments against qualitative 

 divisions and the theory of determi- 

 nants, and in favor of epigenesis. 



c. Effects of abnormal stimuli on develop- 

 ment. 

 Herbst, Formative stimuli in ontogeny. 



Evidence against distinction between germ- 

 plasm and somatic idioplasm afforded by the 

 phenomena of regeneration and budding. 

 G. Wolff, regeneration of the lens in Trito?i. 



Evidence against Weismann's view of the re- 

 ducing divisions. 



Strasburger, different number of chromo- 

 somes in sexual and asexual generation of 

 plants. 

 Corresponding phenomena in animals. 



Brooks's criticism of amphimixis as a cause of 

 variation. 



The extermination of families. 



O. Hertwig (1892, 1894). 



The idioblasts. 



Their fusion during fertilization. 



The structure of the adult only indirectly the 

 result of the structure of the idioplasm of the 



Every cell-division quantitative only. 



Development a process of epigenesis. 



Each stage in ontogeny determines only the next 

 stage. 



