SOME PROBLEMS OF REPRODUCTION. 15 
cerned in this process degenerates into mucus, while the rest 
rounds off, awaiting fertilisation. This process is obviously a 
purely adaptive one, destined merely to favour the approach 
and entrance of the spermatozoon. 
Similar “ excretions” occur elsewhere for similar purposes ; 
thus in Peronosporeex, Saprolegniex, and Chytridiee 
the asexual zoosporange forms a beak for the discharge of the 
zoospore ; in Chytridiew the protoplasm which fills this beak 
undergoes degeneration; while in Saprolegniee it is re- 
tracted and absorbed into the body of protoplasm not yet fully 
differentiated into zoospores. In the Chytridian Woronina 
polycystis, which I have studied myself, the formative pro- 
toplasm of the beak contains a nucleus, and appears to be a 
zoospore degraded for the purpose of opening a gate to its 
sisters.!_ Hence neither physiologically nor morphologically 
can excessive stress be laid on such a degradation, whether of 
cytoplasm or nucleated protoplasm. 
The spermatogonia of Oedogoniez are formed by re- 
peated bipartitions of the vegetative cells, and are short and 
discoid. In each spermatogonium the protoplasm rounds off 
and divides to form two naked spermatozoa; or this division 
is suppressed, and the protoplasmic body of the spermato- 
gonium escapes as a single spermatozoon. The spermatozoa 
have, like the asexual zoospores, a subapical ring of cilia, but 
are smaller. In certain species the discoid cells produce not 
spermatozoa, but so-called “ androspores,” of similar character 
but of different fate. For the androspores settle on the base 
of the oogonial cell-wall and develop into ‘‘ dwarf male” 
plants ; all the cells of these (save sometimes a sterile basal 
cell) are spermatogonia, and behave like the same organs in 
the other species. This is the first case in which we find sex 
anticipated by or reflected back upon individuals or 
organs antecedent to the gametogonia.” 
1 As stated by me in a communication to Section D of the British Asso- 
ciation at Leeds, 1890, Report, p. 872. 
2 The colonies of Kudorina and some forms of Volvox only produce 
gametes of one sex, but have no other peculiarity to distinguish them. 
