457 
Zygospores of Sporodinia grandis. 
kinds appear, some of which are two or three times the size of the ordinary- 
nuclei and have a dense, spherical, red-staining nucleolus. The smaller 
nuclei are finally reduced to nucleoli that stain red. 
At an older stage, when oil begins to accumulate in the centre of the 
zygospore, the nuclei are still evident in the protoplasm. No difference in 
the size of the nuclei is noted at this time. In the mature zygospore, the 
oil globule is very large and the protoplasm has become reduced to 
a parietal layer, dense at certain points and vacuolate over the rest. 
Mucorine crystals are present at this stage. 
Maurice Leger (22) made a more extensive study of this form. He 
described many of the structures that more recent study has brought out. 
He describes the pyriform swellings that fuse as similar, and emphasizes 
their absolute isogamous nature. His account varies little from that given 
by himself and Dangeard, up to the point where the zygospore is formed. 
He lays some stress on the formation of a peculiar structure in the walls 
adjacent to the suspensors, and interprets it as a canal. He also describes 
the disintegration of some nuclei. The protoplasm becomes vacuolate, and 
appears as a sponge filled with oil. The nuclei disappear, and at the same 
time certain deep-staining bodies, difficult of interpretation, become evident. 
They arise as small spherical bodies, towards the extremities of the zygo- 
spore. Leger is uncertain regarding their origin, but concludes that they 
arise either from the large nuclei or from special portions of the protoplasm. 
He was unable to detect any details of structure. These spheres are 
isolated at first, but ultimately arrange themselves in a spherical zone 
around an oil mass. He describes these masses as varying in size in the 
different zygospores, but as being uniform within the same one. These 
small spheres Leger calls ‘ spheres embryogenes ’, and the larger ones 
resulting from their fusion he calls the ‘ spheres embryonnaires ’. He 
justifies the terms on the basis of his interpretation of their ultimate 
function, namely, that they act directly in the reproduction of the plant 
when the zygospores germinate. 
In germination, the spheres enlarge and fuse, although he can discern 
no definite organization in them. Characteristic nuclei appear again ; 
they divide and pass out into the hyphae. The oil is absorbed little 
by little. 
In summarizing, Leger emphasizes the importance of the ‘embryo 
spheres saying that these bodies constitute a sort of embryo which develops 
into a new plant at the time of germination. 
In 1901 Gruber (20) undertook the further investigation of this form 
and failed to find the structures described by Leger. He was unable to 
observe either fusion or disintegration of the nuclei. He suggests that we 
have to do with processes similar to those displayed in the Oomycetes, but 
gives no evidence in support of this suggestion. 
