332 MONTGOMERY. [Vol. XV. 



Riickert ('92) studied the maturation of the eggs of ScyHium, 

 Pristiurus, and Torpedo. In young germinal vesicles there 

 are a few small nucleoli, most of them peripheral in 

 position. In larger ova they have increased in number and 

 size, and become grouped in a cluster at that part of the nucleus 

 which is nearest the animal pole of the egg ; this cluster may 

 occupy one-fourth of the whole space of the nucleus. Later, 

 but still antecedent to the formation of the pole spindles, the 

 nucleoli decrease in size and commence to stain very faintly. 

 Riickert considers the nucleolus of an egg cell as strictly com- 

 parable to that of any somatic cell. From the fact that the 

 nucleoli are largest, and color most intensely, at the same time 

 that the chromosomes do, and simultaneously with the latter 

 become gradually invisible later, he concludes : "dass es die 

 Stoffwechselvorgange der Chromosomen sind, zu welchen die 

 Nucleolen in direkter Beziehung stehen, sei es nun, dass sie 

 notwendige Stoffe an die letzteren abgeben (vielleicht das Chro- 

 matin, wie schon Flemming vermutete), oder dass sie Stoffe 

 von ihnen aufnehmen, oder endlich dass beides zugleich der 

 Fall ist. . . . Spater f reilich, wenn die Chromosomen merklich 

 an Substanz verlieren, wird man eher geneigt sein, die betref- 

 fenden Nucleolen als Trager von Zerfallsprodukten der Chromo- 

 somen anzusehen." He also observed that the number of the 

 nucleoli varies in different germinal vesicles of the same age, 

 that a number may coalesce to form a larger one, and that a 

 few wander out into the cytoplasm, where they become paler 

 and finally vanish. 



Wiren ('92) found that the smallest germinal vesicles of Chae- 

 toderma contain no nucleoli ; in nuclei of about i5/i diameter a 

 nucleolus appears for the first time, and consists of a dense 

 mass of granules, which stain differently from the other nuclear 

 granules. More than one nucleolus is never to be found. 



1893. 



Van Bambeke ('93) found one to five homogeneous nucleoli 

 in the germinal vesicles of Scorpae7ia scrofa, and notes that in 

 older eggs they do not stain as deeply with carmine as in 

 younger ones. 



