82 HELEN DEAN KING. 



resolution of the nucleoli into chromatin threads. In all the 

 eggs that I have examined in which the germinal vesicle was in- 

 tact, the chromatin was always in the form of distinct chromo- 

 somes. These chromosomes had no connection whatever with 

 the large round nucleoli which, with the combination stain used, 

 always stain a deep blue while the chromatin invariably takes 

 the carmine. I have frequently noticed, however, that many of 

 the chromosomes end in small granules which take the same 

 stain as the chromatin and that there are a number of simi- 

 lar granules scattered throughout the-nucleus. Recent work on 

 various forms has shown that unquestionably the term nucleolus 

 has been applied to many different kinds of structures in the 

 germinal vesicle. As a general term used to cover any definite 

 structures in the germinal vesicle other than chromosomes, linin 

 and karyoplasm, it may, perhaps, be fitly applied both to the 

 large rounded structures (which I consider the only true nucleoli 

 in the germinal vesicle) and to the smaller granules which stain 

 like chromatin and which I believe to be chromatin that is not 

 used for the chromosomes. The structures which, in my 

 opinion, are the true nucleoli have nothing to do with the forma- 

 tion of the chromosomes for the first polar spindle, as they are 

 never connected with the chromosomes in any way and can be 

 traced step by step until they are absorbed by the cytoplasm of 

 the egg after the spindle is completely formed. 



Many of Carnoy and Lebrun's illustrations of the forma- 

 tion of the first polar spindle in the egg of Bufo vulgaris are 

 strikingly like my own, but we differ somewhat in our interpre- 

 tation of them. According to their view, when the crerminal 



o ^> 



vesicle in the egg of Bufo vulgaris migrates towards the upper 

 pole, and before the nuclear membrane disappears, the paired 

 chromatin filaments (which are exactly like those I find in Bufo 

 lentiginosns during the same period) break up into small granules 

 which cannot be distinguished from the granules of karyoplasm. 

 All the nucleoli suffer tJic same fate as the chromosomes excepting 

 about ten ivhich remain to form the chromosomes of the first polar 

 spindle. The karyoplasm meanwhile, forms a pronounced radia- 

 tion from the " plage fusoriale " at the lower pole of the germinal 

 vesicle. " Les nucleoles predestines montent le long des fila- 



