524 MOiVTGOMERV. [Vol. XV. 



10. Discharge of Nucleolar Substance from Resting Nuclei. 



Will ('84) holds that the larger nucleoli of the amphibian ger- 

 minal vesicle pass out into the cytoplasm, and there become the 

 yolk-nuclei ; and Scharff ('88) corroborates this view for the ova 

 of Trigla, though it is opposed by Cunningham ('95). Macallum 

 ('91) concludes that in amphibian ova the peripheral nucleoli 

 generate a substance which diffuses first in the nucleus and from 

 there into the cytoplasm, and that this substance combines with 

 the cytoplasm to form the yolk substance ; Jordan ('93) expresses 

 a somewhat similar view in regard to the yolk formation of the 

 newt. Henneguy ('93) assumes that the corpuscle of Balbiani 

 in the ova of Vertcbrata " est tres probablement une partie de 

 la tache germinative, ou une tache germinative entiere, qui sort 

 de la vesicule [germinative] pour penetrer dans le vitellus," and 

 Mertens ('93) holds a similar view. And for egg cells of 

 Tunicata, Floderus ('96) confirms Roule's ('84) observations, 

 that the " intravitelline Korper " are paranucleoli which have 

 wandered into the cell body. Cf. also Bremer ('95a, b). 



Leydig ('88) finds that in ova of Geopliilus, Steiiobothrus, 

 Raiia, and Tritoji particles of nucleolar substance penetrate 

 into the cytoplasm. Lukjanow ('88) concludes that in the case 

 of the cells of the stomach mucosa of Salamandra, the nucleo- 

 lus discharges a portion of its substance from the nucleus. 

 Humphrey ('94), from observations on plant cells, maintains 

 that in some cases portions of nucleolar substance may pass 

 into the cytoplasm. 



Fol ('83a, b) concludes that the follicle cells of the ascidian 

 egg arise as buds from the surface of the germinal vesicle, 

 and that each of these buds contains a particle of nucleolar 

 substance ; these conclusions are affirmed by Roule ('83). 

 Scharff ('88) supposes that the follicle cells of the ovum of 

 Gadus are derived from nucleoli which have left the germinal 

 vesicle, such nucleoli becoming the nuclei of the new cells. 

 (Ogata '83) studied human pancreas cells and finds that a 

 nucleolus wanders out of the nucleus, becomes a " Nebenkern," 

 and the latter finally changes into the nucleus of a new cell, a 

 conclusion which is opposed by Platner ('89b). 



