223 
Species of Olpidiopsis, (Cornu) Fischer . 
radially arranged strands which communicate with a dense peripheral layer, 
and along which one can frequently observe a movement of granules 
towards the parasite. This gradually disappears as growth of the sexual 
elements proceeds, until at maturity these cells lie in an empty swelling. 
The vacuoles of the oogonium now become less apparent and the 
protoplasm is more or less filled with large and small granules. A similar 
condition prevails also in the antheridium (PL XXIV, Fig. 28). Their 
development is rapid, as is the disappearance of the host protoplasm which 
surrounds them. 
After fertilization the oospore develops a thick endospore. Fig. 30 
shows a mature oospore of O. luxurious bearing two empty antheridial 
cells. The content is differentiated into an outer zone, more or less finely 
granular, and a central mass of large, more or less regular granules in which 
is usually one or more large oil globules. The oil globules are not repre- 
sented in this figure. Occasionally in these species one finds the peculiar 
condition of one antheridial cell attached to two oogonia, one of which 
is usually provided with a separate male cell (PI. XXVI, Fig. 88). Fig. 85 
shows a young oogonium with three antheridial cells attached. 
The fertilization pore in the sexual spores of these species is, so far as 
can be determined in the living material, not unlike that described for 
O . vexans. It has frequently been observed, and in some few cases the 
stream of male protoplasm could be seen passing through it into the female 
cell. In one interesting case, while observing this act, the weight of the 
cover-glass, because of evaporation of water under it, suddenly came upon 
the oogonium as the last of the antheridial contents was passing into it. 
Immediately a stream of protoplasm was forced through the pore and the 
male cell was soon refilled. 
As yet, no case of germination of the oospores has been observed for 
any of the species studied. A. Fischer (11) witnessed the germination of 
the resting spores of Olpidiopsis (P seudolpidiuni) and Zopf the same pheno- 
menon for O. Schenkiana. In both cases germ tubes were formed through 
which zoospores escaped. 
Reinsch (21) observed, in a species of Olpidiopsis (according to A. Fischer 
0 . minor), that at the point of fusion of the two sexual cells a slit formed 
in the wall which permitted the passage of the male protoplasm into the 
oogonium. This opening, after fertilization, was closed by growth. 
In O. Schenkiana Zopf (26) saw no communicating pore or opening 
between the two sexual cells. To him the contents of the antheridium 
seemed to diffuse through the wall into the oogonium. I have not had the 
opportunity to observe the condition in that species, but judging from the 
ease with which such a pore might be overlooked in the species studied, 
it seems probable that it occurs in O. Schenkiana. 
