SEXUAL REPRODUCTION. 169 
walls of the conceptacle in order to group themselves at the 
centre, where they float in a watery fluid, These gonosphercs 
are then smooth and bare, with no membrane on their surface 
of the nature of cellulose. 
During the formation of the oogonia there arise from its 
pedicel or from neighbouring filaments slight cylindrical curved 
branches, sometimes turned round the support of the oogonia, 
and which all tend towards this organ. Their superior extremity 
is intimately applied to its wall, then ceases to be elongated, 
becomes slightly inflated, and is saab below by a ee 
it is then an oblong cell, slightly 
curved, filled with protoplasm, and 
intimately applied to the oogonia— 
in fact, an antheridium or organ of 
the male sex. Each oogonium pos- 
sesses one or several antheridia. 
Towards the time when the gouo- 
spheres are formed it may be ob- 
served that each antheridium sends 
to the interior of the oogonia one 
or several tubular processes, which 
have crossed its side wall, and which 
open at their extremity in order to ee ee ee 
discharge their contents. These, jpecenosa, (Cornu) 
while they are flowing out, present some very agile corpuscles, 
and which, considering their resemblance to those in TVaucheria, 
to which the name of spermatozoids are applied, ought to be 
considered as the fecundating corpuscles. After the evacuation 
of the antheridia the gonospheres are found to be covered with 
cellulose ; they then constitute so many oospores, with solid 
walls. De Bary considers that, bearing in mind analogous 
phenomena observed in Vaucheria, and the direct observations 
of Pringsheim,* the cellulose membrane on the surface of the 
gonospheres is only the consequence of a sexual fecundation. 
in Achlya dioica the autheridium is cylindrical, the plasma 
which it encloses is divided into particles, which attain nearly 
* Pringsheim’s ‘ Jalrbucher,” vol, ii, p. 169, 
