238 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
nuclei lie side by side and do not fuse until the warts are being 
formed on the oospore. Peronospora parasitica (Wager, :00) rep¬ 
resents a case of delayed nuclear fusion in the Peronosporineae. In 
this species, nuclear fusion does not take place until a well devel¬ 
oped wall has been formed about the oospore. Fusion then occurs 
and the oospore remains uninucleate until germination. Wager 
points out another interesting fact about the sexual nuclei of Pero¬ 
nospora parasitica. He finds that they approach each other soon 
after the sperm nucleus is introduced, then separate for some time 
and finally approach the second time and fuse. When the sperm 
nucleus is first introduced into the oosphere of Araiospora the sex¬ 
ual nuclei approach and put out beaks. Later, during the period of 
growth they become spherical but remain close together. In 
Pythium nltimum (Trow, :01), “the male and female nuclei do not 
fuse until a thick oospore wall has been produced.” Polyphagus 
(Wager, ’99) represents a more extreme case of delayed nuclear 
fusion. Here the sexual nuclei remain distinct during the entire 
development of the thick walled resting spore and fusion takes place 
only in the initial stages of germination. It will be seen that 
Araiospora furnishes additional evidence of the independence 
between nuclear fusion and the excitation to activity of the ferti- 
lized cell. 
The origin of the Oomycetic Pliycomycetes is far from clear at the 
present time. Moreover, recent investigations and the accompany¬ 
ing conclusions tend to make the question even more obscure. The 
writer is not strictly in sympathy with the view that deviations in 
the details of nuclear migration or even division be given more prom¬ 
inence than many other facts of structure and development. - Con¬ 
trary to the view expressed by Lagerheim (:00) it still seems 
reasonable that Vaucheria-like forms present the strongest indica¬ 
tions of relationship with the Oomycetic fungi. Lagerheim believes 
that Monoblepharis is derived from Oedogonium-like ancestors and 
this conclusion is based chiefly on the ground that its oogonium is 
always uninucleate while that in Vaucheria is multinucleate until 
just before the septation is formed. Before abandoning this view 
of the origin of at least a portion of the Oomycetic Phycomycetes, 
it is certainly important to know more of the manner in which the 
multinucleate zoosporangia of Monoblepharis bisignis and JSL 
fasciculata arise. 
