456 Keene. — Cytological Studies of the 
Both admit, however, that multiple fusions of nuclei may occur even in 
Albugo Candida. 
Davis ( 16 ) has studied Vaucheria geminata, a coenocytic Alga, and has 
found that the oosphere is multinucleate when first formed, but, by a process 
of rapid and complete degeneration of all the nuclei except one, the egg at 
the time of fertilization contains only one functional nucleus. 
Although there has been a great deal of investigation in the Zygo- 
mycetes , a group of Fungi which furnishes very favourable material for the 
study of the fusion of multinucleate gametes, the results are contradictory. 
All investigators have encountered structures that they have described 
under different names and to which they have attributed various functions. 
All have admitted that the interpretation of these structures was difficult. 
Therefore it has seemed advisable to make an attempt to substantiate the 
results of one or the other group of workers, and to explain, if possible, 
the nature and function of the various structures found in developing 
zygospores. 
As early as 1820, Ehrenberg ( 18 ) described the process of conjugation 
in a form that he termed Syzygites , now known as Sporodinia , one of the 
Mucorineae. In 1864 de Bary described, in much greater detail, the same 
form. According to de Bary, * the true fruiting branches are branched 
dichotomously repeatedly. On every two of the hyphae are formed pear- 
shaped enlargements. The suspensors grow toward each other, meet, the 
ends are cut off by partitions, and in this manner the gametes are formed. 
The membranes on the contiguous surfaces are dissolved away, the contents 
fuse, and so results the zygospore. The same is encircled by three 
membranes, the outermost of which is dark brown, warty, and cutinized, 
formed by the membranes of the copulating gametes. The two inner ones 
belong to the zygospore itself’ ( 17 ). 
Through the work of Brefeld ( 2 ) in ] 872, and also that of Van Tieghem 
and Le Monnier ( 31 ), the Mucorineae are well known from a morphological 
point of view. These authors, however, have gone no further into the 
internal structure of these forms than to say that the protoplasm contains 
many nuclei. 
In 1894-5 Dangeard and Leger ( 11 ), using the more modern methods 
of histology, undertook to work out the internal processes of the developing 
zygospores of Sporodinia grandis. They describe the young zygospore as 
a cask-like structure, with an outer cutinized envelope, which has character- 
istic papilla-like projections. Internally, the protoplasm is dense and 
homogeneous, containing many nuclei. The separating walls are dissolved, 
leaving the gametes in free communication. The lateral walls show 
a central brown spot and a number of small openings which favour inter- 
change with the suspensors which contain nuclei and protoplasm. The 
protoplasm is reticulate with meshes towards the surface. Nuclei of two 
