459 
Zygospores of Sporodinia grandis . 
the median line, and the small nuclei are still very numerous. It is not 
rare to encounter at this time two nuclei symmetrically placed. The part 
played by the nuclei which accumulate at the periphery is to preside at the 
formation of the membrane. I have not seen any disintegration as indicated 
by Dangeard. Later the two large nuclei come together, touch and unite 
to form a single mass occupying the exact centre. Finally, in the more 
advanced stages, one finds only a single body from which the protoplasm 
radiates. 5 
Lendner carries his investigations only to partly mature zygospores. 
Furthermore, he uses but a single stain, anilin-safranin, which is not 
sufficient to differentiate the various structures found within the zygospore. 
In 19 1 1 Moreau ( 26 ) investigated several forms: Sporodinia grandis , 
a Mucor , and Zygorynckus . In Sporodinia and Mucor he merely cor- 
roborates the work of Dangeard. In Zygorynckus he went further into the 
details of development and found varying structures. All the nuclei in this 
form are said to disintegrate, except four, which fuse in pairs, leaving two 
nuclei in the mature zygospore. 
In January, 1912, Miss McCormick ( 25 ) published a preliminary note 
on some investigations on the closely related form, Rhizopus nigricans . She 
described many nuclei in the younger stages. All of the nuclei disintegrate 
except two. These, in connexion with coenocentra, increase greatly 
in size without the occurrence of any nuclear fusions. According to 
Miss McCormick, these coenocentra were examined by Professor Stevens, 
who considered them as similar to the structures described by him in 
Albugo . Miss McCormick indicates in her work that the coenocentra 
have their origin at the point of contact of the suspensors before the 
gametangia are cut off. The coenocentra persist until late, and there 
are many nuclei of the same size as those of the mycelium in the mature 
zygospore. Neither fusion nor division of the nuclei was observed by her. 
She describes the presence of a single large oil globule in the mature 
stages, while, in the younger stages, the oil is diffused throughout in small 
globules. 
In a general brief review of the literature that has been available 
on this problem, it is evident that the details of nuclear processes in the 
fusion of the gametes are in doubt. On the one hand, Leger, Dangeard, 
and Moreau hold that numerous nuclei are present at all stages, and that 
nuclear disintegration occurs in the zygospore. Dangeard and Moreau 
describe nuclear fusions which occur between many pairs of nuclei. On the 
other hand, Lendner in Sporodinia and Miss McCormick in Rhizopus find 
numerous nuclei in the younger stages only. At maturity all the nuclei, 
except two, disintegrate. Dangeard and Miss McCormick describe structures 
comparable to the coenocentra of Stevens. 
