SPORODINIA.—CLOSTERIUM AND COSMARIUM. 71 
SPORODINIA. 
Morphologically considered, the sexual process in Sporodinda 
grands and in other typical Zygomycetes seems to be similar to that 
in the Conjugatee, but in Sporodinéa the gametes are multinucleate, 
and the behavior of the nucleiinthe young zygote varies considerably, 
according to the accounts given by the different observers. After the 
cytoplasmic fusion of the gametes, the nuclei of each arrange them- 
selves into a spherical layer surrounding a globule of oil, and then 
fuse, producing a hollow sphere full of oil, which Léger (95) has 
called an embryonic sphere (sphere embryonnaire). These embryonic 
spheres lie near the poles of the zygote. During the germination of 
the zygospore the two embryonic spheres fuse. The fused mass 
reveals numerous nuclei, which pass into the sporangiferous mycelium 
and begin to divide. In the azygospore only one embryonic sphere is 
developed. Wager (’99) regards the union of the nuclei to form the 
embryonic sphere as the sexual act, and the azygospores are, there- 
fore, truly sexual, the process of conjugation being of secondary 
importance. Dangeard (’94, ’95) does not accept Léger’s interpreta- 
tion of the embryonic spheres, holding that the fate of the nuclei has 
not been determined. 
According to Gruber (’o1) no embryonic spheres are to be seen in 
the newly formed zygote. The numerous nuclei, on the contrary, are 
uniformly distributed throughout the cytoplasm. After five or six 
weeks the same condition of things was still found to exist, and what 
took place finally among the nuclei Gruber was unable to determine, 
Neither fusion, disorganization nor division of the nuclei was observed 
even six months after the fusion of the gametes. 
From what is now known concerning the sexual union of multinu- 
cleate gametes in other groups of plants, in which the sexual process 
has been unmistakably followed in every detail, it is very probable that 
a multiple fusion of the nuclei in pairs obtains also in Sporodinza.' 
CLOSTERIUM AND COSMARIUM. 
In the desmids the process of fecundation agrees essentially with 
that described by myself for Spzvogyra, except as regards the time of 
the fusion of the sexual nuclei and the behavior of the chromatophores 
in the zygospore. During the development of a firm cell-wall about 
the zygote, according to Klebahn (’91), the chromatophores undergo 
a marked change, the result of which is the formation of two large 
rounded balls, which are at first rich in starch and of a yellowish 
color, The part taken by the four original chromatophores in the 
1 See Chapter III, A/dugo Bliti, and Chapter IV, Pyronema. 
