MUSEUM OF COMPARATIVE ZOOLOGY. 255 



it as a network of very delicate protoplasmic filaments composed of a homo- 

 geneous matrix and of granulations arranged in line. Within this network, 

 which stretches through the whole cavity of the vesicle, the germinative dot is 

 suspended, so that the filaments which, by their ramifications and anastomoses, 

 form the network proceed from the dot. A similar reticulum is found in the 

 case of the cat, the rabbit, and mollusks. In the latter instance, there are, be- 

 side the germinative dot, other smaller spherical corpuscles, one to seven in 

 number, which are' intensely stained in haematoxylin, or carmine. A short 

 distance from the germinative dot is sometimes seen a pale transparent vesicle, 

 which is not stained. 



In a subsequent note Trinchese ('77) finds, in addition to the principal 

 germinative dot and several accessory ones,* an irregular body, to which he 

 gives the name " grumo " (clot). This presents prolongations which are con- 

 tinuous with the network filling the cavity of the germinative vesicle. The 

 germinative dot and the grumo are both stained in hsematoxylin ; if sub- 

 sequently submitted to ammoniacal carmine, the dot remains violet, but the 

 grumo is stained red. 



In his recent paper on the structure and development of the vertebrate ovary, 

 Balfour ('78^) has given considerable attention to the structure of the nuclei, 

 especially those of developing ova, and the successive changes which they un- 

 dergo, — changes that are not brought into connection with cell-division. The 

 ovaries studied were those of selachians (Scyllium, Raja) and mammals (princi- 

 pally rabbits). During the conversion of primitive into permanent ova (Scyl- 

 lium) the nuclei undergo certain alterations which are the same whether the 

 primitive ova retain their individuality and all become permanent ova, or in 

 groups suff'er a confluence into polynuclear masses (syncytia), out of which result 

 a diminished number of permanent ova.f The nuclei increase in size, and, in 

 place of being granular, become delicate vesicles filled with a clear fluid, con- 

 taining, close to one side, a granular mass, which stains very deeply with color- 

 ing reagents. The granular mass becomes more or less stellate, and finally 

 assumes the form of a reticulum, with one or more highly refracting nucleoli 

 at its nodal points (p. 416). Balfour thinks that the deeply staining granular 

 mass constitutes a part, but not, as is maintained by Semper, the whole of the 

 nucleus (p. 393). In addition to the ordinary mode of increase for nucleoli (viz. 

 by division into two), there sometimes appears to be a production of numerous 

 smaller nucleoli within a larger nucleolus, comparable with endogenous cell- 

 formation. These nucleoli doubtless become free. Certain structures, variable 

 in size, which are found in the yolk, are thought to be nucleoli thus set free 

 (pp. 412, 413). The reticulum, which is conspicuous in the germinal vesicle of 

 freshly formed ova, becomes granular and less distinct in older ones. The 



* A misprint in the Jahresbericht of Hofmann and Schwalbe (Bd. VI., Anat., p. 15) 

 makes Trinchese appear responsible for the existence of several " Keimbldschen." 



t A portion of the nuclei in the latter case atrophy and become " pabulum for the 

 remainder "; the metamorphosis of these is, of course, not embraced in what foUows. 



