3 C. ISHIKAWA. 



from tlie nucleoluis or independently in the nuclear plasma. At all 

 events the nncleolas here hi in stages of regressive metamorphosis, and 

 in many cells in these stages no trace of it can be seen within the nu- 

 cleus. As with the similar developmeritnl stages of spermatic cells, 

 I will call the stage after this the zone of rq)eiii7iij. 



Fiof. 25 shows two neio-hbourinsf eofo-s of an animal in which the 



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eight dumb-l)e]l shaped chromatic elements have appeared. The 

 u'crmiiial vesicle has now attained its Isu'o'est size. In one of them, on 

 the left liand side of the figure, we see besides the eight chromatic 

 elements a germiijal spot, (now greatly reduced in size), and nine small 

 round vesicular bodies which certaiidy correspond to the micronucleoli 

 of Haeclicr. In tlie germinal vesicle of the other egg, the germinal spot 

 is no more to be seen. This figure is compounded from three suc- 

 cessive sections, in such a manrjer that from the first and second 

 sections the eo-o^ on the left side is drawn, while from the second and 



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third sections that on the riodit side is drawn. 



o 



c. The Zone of Bipeninfj. — As îdready stated, there is no distinc- 

 tion between the eggs in the last zone and those in the zoiie of 

 rii)eniii"', and tlie eii'u'S u'o throuji'h, in one and the same zone, the 

 changes mentioned under the headinii" of the u'rowinii' zone and the 

 changes tliat are now to l)e mentioned ; so tliat these two zones are 

 not distinct in the o^arian sac, as they are in the testicular sac. The 

 onlv reason for counting them separate consists in the advantage ol)tain- 

 ed when we come to conijiare these two kinds of germ cells together. 



The esrs" cells, as mentioned above, now show distinct chromatic 



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elements each in the shape of a dumb-bell. These are eight in number 

 and are scattered about without any order in the nucleus. Shortly 

 after the appearance of the chromatic elements the micronucleoli as 

 well as the nucleolus disappear, and the nudear mendjrane becomes 

 also indistinct and finally disappetu's. 



