Trow. — The K ary o logy of Saprolegnia. 633 
the conclusion that in the later stages of the development 
of the oogonium the substance of the nuclei becomes finely 
divided and distributed through the protoplasm. Such a view, 
while manifestly incorrect, might be formed naturally enough 
from a study of unsatisfactory preparations : my own earlier 
work caused me to form a somewhat similar opinion. It is 
difficult, however, to see in what way Dangeard could come 
to the conclusion indicated if the nuclei really undergo 
fusions. 
I may also refer to Hartog s description of the nuclei at this 
critical stage of development of the oogonium, already given 
on p. 613. In particular, the fact that the chromatin-masses are 
smaller tells strongly in favour of division, and that ‘ they take 
up stain less readily 5 appears to confirm the observations I have 
already made on degeneration . 
Vacuoles in the Oogonium. The vacuoles in the oogonia 
have given rise to much discussion. In recent years they 
appear to have been confounded with the nuclei, as in former 
times they were confounded with the pits in the wall of the 
oogonium. They occur in the protoplasm of the oogonium 
from the time that the reducing division has led to the 
liberation of the paired rods up to the formation of the thin 
layer of protoplasm. They virtually exist then during the 
time that the degeneration of the nuclei is going on. They 
occur in their most typical form, as represented in Fig. 11 a, at 
the time of the completion of the division of the nuclei. The 
study of sections, moreover, shows that they are even more 
irregular and inconstant than would be suspected from a study 
of the fresh material. I believe that many of the so-called 
vacuoles observed in fresh material are simply thin places in 
the lining layer of protoplasm, as may be seen, for example, 
in Fig. 11 b. They have no morphological connexion with 
the nuclei, and with their possible physiological importance we 
cannot concern ourselves here. They cannot possibly be the 
means, as Hartog supposes, of bringing the fusion-nuclei into 
proximity with each other : this is well seen in Fig. 11 a, where 
the vacuoles are well developed, but the small nuclei are 
X X 
