278 
Wager.—On the Fertilization 
of nutrient material in the cytoplasm. The male nucleus 
is at first slightly smaller than the female, but they soon 
become approximately of the same size and exhibit the same 
structure. 
7. The fusion takes place while the nuclei are in the resting 
stage and not until the zygote is nearly ripe. 
8. Before fusion takes place the central body disappears. 
9. The ripe zygote is uninucleate. It contains a central 
large pale oil-globule and a peripheral layer of granular pro¬ 
toplasm, in which the nucleus is placed. The nucleus can 
be seen in the living condition as a pellucid spot in the proto¬ 
plasm. 
10. Of all the nuclei in the oogonium only one is set apart 
for the purpose of reproduction; the others remain in the 
periplasm and are used up to form the protective layer or 
layers of the oospore. 
11. No difference is observable between the sexual nucleus 
and those that remain in the periplasm. They are the same 
size, have the same structure, and stain in a similar manner. 
It is probable therefore that all the nuclei of the oogonium 
are potentially sexual. In C. Bliti , as shown by Stevens, it 
appears to be a mere accident that determines which of the 
nuclei in the periplasm shall give off daughter-nuclei to 
the oosphere. 
12. On comparing the various methods of fertilization and 
oospore-formation in the Peronosporeae, we can, so far, dis¬ 
tinguish • three types. (1) Uninucleate oosphere, binuclear 
fusion and uninucleate oospore (P . parasitica). (2) Uninucleate 
oosphere, binuclear fusion and multinucleate oospore ( C . 
candidus , C. Portulacae and P. Ficariae. (3) Multinucleate 
oosphere, multinuclear fusion in pairs and multinucleate 
oospore ( C. Bliti). Whether Pythium will have to be regarded 
as a fourth type can only be decided by further investigation. 
