8 



ART. 17. — N. YATSÜ. 



I have tried in vain by using neutral red and other intra- 

 vitam stains^ to make out zonal or other differentiations and 

 especially the effect of the spermatozoon upon the cytoplasm of 

 the living egg. Yet from Series B it will not be too unreason- 

 able to assume that in the nemertine egg there takes place by 

 dint of the action of the spermatozoon some change not very 

 different in nature, though perhaps less in degree, from the 

 visible rearrangement observed in the egg of ctenophores, teleosts, 

 ascidians, etc. 



Series C. Removal Experiment performed after the 

 Formation of two Polocytes. 



Fig. 4. 



A, diagram showing tlie operation in Series C ; B, pilidium with defec- 

 tive gut resulting from the cut indicated in b; C, pilidinra from the egg 

 from" which a large portion of cytoplasm had been cut off as in c. 



2 Neutral red beautifully stains the plasma-granules of both the blastulas and gastrnlas 

 of C lacieus. 



