SOME PROBLEMS OF REPRODUCTION. 21 
tents of the female plant condensing into one or more 
“oogonia” (?), that of the male into “ antheridia,”’ which 
open one into each “oogonium ;” the whole of the male proto- 
plasm passes over into the oogonium by siphonogamy, and 
the two plasmas fuse to form the zygote. Though we have 
no information as to the cytology of this group, it would seem 
probable that either gamete has a nucleus formed by the fusion 
of several vegetative nuclei, and that the zygote is also uni- 
nucleate. No epiplasm is formed. 
CHYTRIDIE# present conjugation in various modes; in many 
cases the “ gamete” contains all the protoplasm of the plant, 
which we know to be apocytial in the vegetative state ; but we 
have no evidence as to the nuclei of the so-called gametes and 
zygote. Conjugation has been observed in four genera: 
Polyphagus by Nowakowski,! Olpidiopsis by Zopf, 
Zygochytrium and Tetrachytrium by Sorokin.’ 
In the two former genera all the protoplasm goes into the 
gametoid. In Polyphagus the gametoids are formed by two 
distinct plants somewhat different, and the uuion is siphono- 
gamous. In Olpidiopsis the gametoids are differentiated by 
the separation of a single apocytium into a larger part, the 
‘‘oogonium,” and a smaller part, the ‘‘antheridium ;” the latter 
is at first completely shut off by a cell-wall which becomes 
perforated, admitting the whole of the protoplasm of the an- 
theridium to enter and fuse with that of the oogonium, as in 
Ancylisteze. In both genera the zygote is a “ resting spore.”’ 
ZycocuytRium forms gametoids on outgrowths of its myce- 
lium which conjugate in (moncecious) pairs, like those of 
Mucor. 
TETRACHYTRIUM forms, in terminal enlargements of the 
mycelium, numerous one-ciliated zoospores which are euisoga- 
mous, conjugating in pairs as soon as they leave the sporangia. 
“Zur Kenntniss. der Phycomyceten,” in ‘Noy. Act. Ac. Leop. Carol.,’ 
vol. xlvii, 1885. 
1 In Cohn’s ‘ Beitrage,’ vol. ii. 
2 «Bot. Zeit.,’ 1874, p. 308. 
