Trow . — The Karyology of Saprolegnia. 645 
mentioned as phenomena of which a similar explanation may, 
with great probability, be given. A thorough investigation of 
the nuclei of these plants is much to be desired. 
The occurrence of fertilization in the androgynous forms is 
certainly very curious and puzzling. Nuclei, so closely related 
by descent as to be less than ten generations distant from 
each other and maintained throughout life under apparently 
identical external conditions, pass into the separate gametangia, 
and after undergoing a reducing division fuse with one another 
to form the nucleus of the zygote. This phenomenon seems to 
involve the assumption that the nuclear divisions are qualita- 
tive as well as quantitative in character. If this be so, the 
advantage of the sexual process in promoting variability is 
evident. 
I should like to make clear that there is nothing exceptional 
in the degeneration of nuclei as described in these plants, and 
any peculiarity in the details of the phenomena are readily 
explained as special adaptations. The majority of gametes, 
in the animal as well as in the vegetable kingdom, die, and 
are a serious loss to the organism, or rather to the species. 
The gameto-nuclei in the oogonia of Saprolegnia which are 
present in excess of the required number evidently die, but 
they are not a great loss to the plant, as their substance is 
almost certainly utilized by the oogonium at once as food, or 
is stored up as reserve material for future use. The proto- 
plasm, which we may regard as having belonged to the defunct 
nuclei, is not lost at all, but goes to increase the size of the 
oosphere — probably a decided advantage to the plant. Thus 
it happens that when the nucleus of the zygote divides after its 
period of rest, the number of nuclei is restored, and the 
requisite protoplasm to furnish each with a sufficiency for 
spore formation is already present. In consequence of this, 
about as many zoospores are produced by the oospores of an 
oogonium as there were nuclei enclosed in it at the time of the 
formation of its basal wall. 
I cannot bring these remarks to a close without recording 
my conviction that Strasburger’s (’94) interpretation of the 
