430 MONTGOMERY. [Vol. XV. 



but in no other cases were these structures in contact with 

 nucleoli. They are also never in contact with the nuclear 

 membrane. Male pronuclei they cannot be, since the fecunda- 

 tion takes place in later stages than those which I have had 

 opportunity to observe. I must conclude, though with reserve, 

 that they are either parasitic Protozoa, or, more probably per- 

 haps, structures which characterize ova of a certain generation. 

 (Compare my remarks on the " pseudonucleoli " of Montagiia. 

 The structure figured by Henneguy ('93), in the immature ger- 

 minal vesicles of Sygnathus may have some connection with 

 these bodies.) 



Chromatin. — The chromatin in the youngest germinal vesi- 

 cles (Figs. 103-105, 112-114) is distributed throughout the 

 nuclear sap in the form of minute microsomes. In the second 

 and sometimes the first nucleolar stage such microsomes can 

 often not be detected, but the whole nuclear substance, with 

 the exception of the nucleoli, appears homogeneous and stains 

 with eosin a yellowish red (Fig. 1 15). This peculiar coloration 

 might be accounted for on the ground that in these stages there 

 is a diffusion of nucleolar substance throughout the nucleus. 

 Towards the conclusion of the second and the commencement 

 of the third nucleolar stage, the minute chromatin microsomes 

 again become evident (Figs. 118 and 130). At the end of the 

 third stage a few chromatin threads begin to arise in the 

 nucleus (Fig. 127), and these stain slightly with haematoxylin 

 in the same manner as the microsomes do ; they appear to 

 arise separately and at different points in the nucleus, and are 

 at first short, but gradually increase in length. As noted 

 above, the small nucleoli of the second generation are often 

 apposed to these threads, and sometimes lie in the meshes of 

 them. 



Niiclcjis. — In the first and second nucleolar stages the 

 nucleus has often short, lobular processes, which may be amoe- 

 boid in life (Figs. 109, 112, 114, 116, 125) ; these changes in 

 the form of the nucleus no doubt stand in a direct relation to the 

 assimilation of yolk substance from the cytoplasm. Towards 

 the end of the third stage the nucleus becomes regular in out- 

 line, with no traces of amoeboid processes ; at this stage also 



