No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 30 1 



Rabl ('85) studied mitoses in cells of the larva of Salamandra, 

 and found that in the prophases of mitosis the nucleoli gradu- 

 ally vanish and take part in the production of the chromatin 

 threads. In the unripe germinal vesicle of Proteus, on the 

 inner surface of its membrane, " sieht man in unregelmassigen 

 Abstanden von einander kugelige, stark glanzende, wie Oel- 

 tropfen aussehende Korperchen," which he assumes are neither 

 nucleoli nor masses of true chromatin. 



Will ('85) studied the ovogenesis of Notonecta and Nepa. 

 The young "Ooblast" contains one nucleolus bounded by a 

 membrane and surrounded by smaller " Chromatinballen" ; 

 subsequently the latter bodies fuse together and form a closed 

 ring around the nucleolus. The nuclear division of the ooblast 

 is an amitotic one, and is preceded by a division of its nucleolus ; 

 in each daughter-nucleus, then, the divided half of the primitive 

 nucleolus breaks up into fragments, which become distributed 

 through the nuclear sap, and the daughter-nucleus produces a 

 new nucleolus without the aid of these particles. When the 

 ovum proper is ripe, the nucleolus finally disappears. 



1886. 



Van Bambeke ('86) found that in the germinal vesicles of 

 Arachnida, Isopoda, Hymenoptera, and Meconenia, the nucleoli 

 and the chromatin do not stain with methylen green (corrobo- 

 rating Wielowiejski) though they stain with carmine and 

 haematoxylin ; " Rien ne s'oppose, me semble-t-il, a ce que Ton 

 considere le corpuscule germinatif comme etant equivalent a 

 I'ensemble de la charpente chromatique des noyaux ordinaires 

 [somatiques]." He concludes that there is no proof of the 

 identity of the true nucleoli of the somatic cells with the ger- 

 minal spots of tgg cells. Two stages in the formation of the 

 nucleolus may be distinguished in the ova of various Arachnids 

 {Lycosa, Amaurobius, Argyronecta, Tegenaria, Attus, T/ieridmm, 

 Epeira, Zilla, Phalajigiiim) : (i) there is a single large nucleolus 

 (sometimes accompanied by smaller accessory ones), in which 

 at first a few vacuoles arise, which later fuse to produce a single 

 voluminous vacuole ; and (2) the nucleolus becomes replaced 

 by a mass of fine granules. In the ovarial ^gg of Amaurobius 



