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[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 Montagna. 
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. 115). 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. 
Nucleus. — 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 
