THE THEORY OF GERMINAL LOCALIZATION 



299 



independently developing pieces." 1 This conclusion seemed to form 

 a very strong support to His's theory of germinal localization, 

 though, as will appear beyond, Roux transferred this theory to the 

 nucleus, and thus developed it in a very different direction from 

 Lankester or Van Beneden. 



A 



c h 



Fig. 131. Half-embryos of the frog (in transverse section) arising from a blastomere of the 

 2-cell stage after killing the other blastomere. [Roux.] 



A. Half-blastula (dead blastomere on the left). B. Later stage. C. Half-tadpole with one 

 medullary fold and one mesoblast plate; regeneration of the missing (right) half in process. 



ar., archenteric cavity : c.c., cleavage-cavity; ck, notochord ; m.f., medullary fold ; ms., meso- 

 blast-plate. 



In an able series of later works Whitman has followed out the sug- 

 gestion made in his paper of 1878, already cited, pointing out how 

 essential a part is played in development by the cytoplasm and insist- 

 ing that cytoplasmic pre-organization must be regarded as a leading 

 factor in the ontogeny. Whitman's interesting and suggestive views 



1 I.e., p. 30. 



