284 REPORT— 1903. 



Turning now to the germinal vesicle, after treatment with methyl 

 green. This body is often extruded intact. As the green solution 

 reaches it, minute refringent granules in constant dancing motion come 

 into view. After oscillating for some time these granules settle down 

 and arrange themselves in a network formation. Here again, as in the 

 case of the microsomes, it is not very easy to say whether the granules 

 pre-existed in the natural state of the egg. In the meshes of the network 

 larger granules (? lanthanin of Heidenhain) were seen. None of these 

 minute granules stained with the methyl green ; in fact, the only 

 structures in the nucleus which take up tliis stain are the chromosomes 

 (strong) and the nucleolus (faintly). The chromosomes appear to be 

 rings or loops of irregular form. They are very thick and roughly 

 moniliform — very different in appearance from the smooth outlined 

 attenuate loops depicted by Korschelt in the nearly ripe egg of Ophryo- 

 trocha. T counted four chromosomes in full- sized eggs of Tomopteris. 

 Korschelt gives the same number for Ophryotrocha. 



The numerous unstainable granules in the full-grown germinal vesicle 

 of Tomopteris appear to correspond to Heidenhain's ' oxychromatin granules, 

 while the substance of the chromosomes — which stains with methyl green — 

 is basichromafin. 



Besides the larger eggs, oocytes with chromatin in the primitive 

 spireme stage wei-e examined after treatment with methyl green. The 

 spireme stains intensely. In somewhat older oocytes with reticular 

 nucleus the nucleolus lies eccentrically in the nucleus, and is surrounded 

 by a vacuole to the walls of which it is moored by radiating threads Qf 

 the network. The growth of the nucleolus keeps pace with the growth of 

 the germinal vesicle and of the oocyte. It is at first homogeneous, but 

 becomes gradually more and more vacuolated. These small vacuoles fuse 

 to form a single large eccentric vacuole. Finally, in full-sized eggs, the 

 nucleolus is smaller, and contains no large vacuole. It seems probable 

 therefore that the decrease in size is due to the collapse of the vacuole 

 and discharge of its fluid contents into the nucleus. 



For sections various methods were tried. The fixing agents employed 

 were chiefly Mann's picro-corrosive-formol mixture, Gilson'smercuro-nitric- 

 acetic fluid, Hermann's fluid, and Boveri's picro-acetic. The Hermann 

 preparations were stained with ihionin or safranin. The others were 

 variously treated, the chief combinations employed being Heidenhain's 

 iron-hsematoxylin with orange green, Delafield's hematoxylin with eosin 

 or congo-red, borax carmine and picro-nigrosin, and nigrosin and 'light 

 green.' On the whole, perhaps the best results were obtained with 

 matei'ial fixed in Boveri's picro-acetic and stained with nigrosin and light 

 green. The latter is a very rapid staining method, and gives a good 

 chromatin-achromatin differentiation. It suffices to stain for one and a 

 half minute in a saturated aqueous solution of nigrosin, and then for 

 half a minute in an alcoholic solution of ' light green.' By this method 

 only the chromatin proper stains black, while the nucleolus and the 

 cytoplasm stain green. The nucleolus is especially prominent in these 

 preparations, appearing as a shining green body. The nucleoli both of 

 the germinal vesicle and tissue cells, such as the epithelium of the gnt, 

 stain similarly with the light green, and do not take up the black. 

 Nigrosin, however, does not distinguish between oxychromatin and 



' Heidenhain, 'Ueber Kern und Protoplasma,' Fentschi-./iir KolliJie-', 1892, &c. 



