M C. ISHIKAWA. 



in tlio rniolen^^ ; ;it the same time a mideolns appears within the 

 nucleus and the egg o-ets int<> the next or the growing zone. 



h. The Growing Zone. — Strictly speaking this zone hegins from 

 the point where the germ-cells get into the dispirem stage. The 

 nuclear threads wliich now appear as minute dots hecome gradually 

 fainter till at last they disappear completely from the view. The 

 o-erminal vesicle too-ether with the eo-g'-cell o^rows larger and lar^'er, 

 and the germinal spot which always remains single also enlarges. 

 As has heen already stated l)y Vaut Mcujcr oî Eupagurus,^^^^ and after 

 him hy myself of Ati/ep]i,ira^^^'^^ the growth of the germinal vesicle is 

 relatively less than that of the cell-body. 



Thus the ovary or germ-gland (" Fveim<lruse '" of C/r/n.s) can also 

 he divided into two ]iarts in accordance witli the descripti(~)n given hy 

 Haech'v of Cyclops. ^'^^ Just as in that case, the blind eiid is characterized, 

 as a!)ove said, bv the presence of a numljer of nuclei in division. Tin's 

 is the "erste Phase der Ovogenese " of iîaé!t'^'t'r and my formative 

 zone. It is f )l]owed by tlie second part, the growing zone, wliich 

 extends from here to the distal end of the oviducts. Here are 

 passed two important stages of ovogenesis, the first o{ which is 

 characterized by the appeara.nce of a nucleolus witln'n the nucleus and 

 the disappearance of the chromosomes, and the second by the formation 

 of the yolk-graiudes, and along with tin's the rapid enlargement of the 

 germinal cells. It will perhaps be better to recognise in this zone two 

 parts according to the stages of development of germ cells, as is d(Uie 

 by Haecker, who takes as the first ])art that portion of a germ glarid 

 where the nuclear membrane appears and the contiMu* (^f the nuclear 

 thread becomes indistinct, and " zuo-leich findet sich ein Xucleolus 

 vor, der Hand in Hand mit der A^erwischung der Schleifenin- 

 dividualität an Grösse zunimmt. jSTeljen diesem grossen Xucleolus 

 zeigen sich schon in sehr jungen Keimzellcü regelmässig ein oder 



