DEVELOPMENT OF DISTICHOPOEA VIOLAOEA. 143 



bodies just considered, but the intermediate stages have not 

 been considered." 



In the species Alpheus Saulcyi and Alpheus hetero- 

 chelis (two varieties) the segmentation is normal and regular, 

 of the centrolecithal type, and the division of the nuclei 

 indirect. In Alpheus minus alone is the segmentation 

 extremely irregular and the nuclear division direct. 



Among Myriapoda we find that the ovum of Julus 

 terrestris is very similar in many respects to that of the 

 Stylasterida3. There are no signs of segmentation, and there 

 is no formation of cells until the time when the epiblast is 

 formed. Heathcote (20), who carefully studied the early 

 stages in the development of this species, could not find any 

 signs of karyokinesis in the first divisions of the oosperm 

 nucleus. 



There is, according to Kingsley (33), a disappearance of 

 the germinal vesicle of the American Limulus, and it is a 

 suggestive fact that Kishinouye (35), in his careful paper on 

 the development of Limulus longispina, does not refer to 

 the first nuclear divisions. 



It is possible that there may be a fragmentation of 

 the oosperm nucleus in the ova of some other Arachnida. 



In the development of many Insecta there are many 

 facts that point to the conclusion that the oosperm nucleus 

 fragments. 



It is noteworthy in the first place that, notwithstanding the 

 fact that several excellent embryologists have carefully studied 

 the development of the common blow-fly, not one of them has 

 been able to give a satisfactory account of the first division of 

 the oosperm nucleus. 



Blochman (3), who figures the spindles of the nuclear 

 divisions in the formation of the polar bodies, and also the 

 spindles of the nuclear divisions of the later stages of embryonic 

 development, did not apparently observe the first division of 

 the oosperm nucleus. He says, *' Als erste Theilung des 

 Eikernes kann man die Bilder wohl nicht auffassen, weil, wie 

 eiu Blick auf die spateren Figuren zeigt, bei Theilungen die 



