294 JORDAN. [Vol. VI 1 1. 



Zellen gcmacht wurden, als zweifellos hinstellen, dass eine 

 Auflosung der Nucleolarsubstanz stattfindet. Die Erklarung 

 dieser Erscheinimg fand ich darin, dass die Nucleolarsubstanz 

 in und vielleicht auch ausserhalb des Kerns zur Verwendung 

 gebraucht werden sollte" (p. 112). My own observations upon 

 the position and behavior of the amphibian egg nucleoli lead 

 me to endorse this view. 



Germinal vesicle as a zuJiole. — The germinal vesicle is de- 

 rived from the nucleus of the germinal epithelium from which 

 the ^^^ first springs. I have never seen any appearances which 

 would indicate that it arises from the union of several epithelial 

 nuclei. 



The germinal vesicle, while still very young, shows a differ- 

 entiation of its substance into three elements — nuclear sap, 

 nucleoli, and chromatin threads or, as I may call them at the 

 outset, chromosomes (Fig. 4). The history of these two im- 

 portant chromatic elements will be dealt with in detail pres- 

 ently. 



A nuclear membrane is visible in the young Q.gg and comes 

 out particularly well in fresh preparations treated with methyl 

 green. This membrane cannot be detected in sections through 

 late stages of the vesicle, but I have not been able to discover 

 the precise period at which it disappears. Its disappearance 

 seems, however, to be contemporaneous with the general 

 vesicular atrophy. 



The amphibian germinal vesicle sometimes presents, as ob- 

 served by O. Schultze, Will, Gotte and others, an irregular 

 and often ragged contour. This has been considered to in- 

 dicate amoeboid movements on the part of the vesicle similar to 

 those witnessed in the nucleus of insect eggs. Schultze ('8?) has 

 given several figures illustrating this condition, — Figs. 5, 18, 

 19, 20. In Diemyctyhis I have observed this appearance only 

 in rather young eggs, and in these the germinal vesicle has 

 assumed the form shown in Schultze's Fig. 5, with sharp pro- 

 jections and jagged contour. Germinal vesicles in newts' 

 ^^■g of the same age as the ones shown in Schultze's Figs. 18 

 and 19, rarely, if ever, display these "amoeboid movements.'* 

 The outer boundary, on the contrary, is smooth, even, and at 



