458 Keene . — Cytological Studies of the 
Dangeard ( 10 ), in a short paper in 1906, describes nuclear fusions in 
the zygospores of Mucor fragilis and Sporodinia grandis , and points out 
that copulation occurs progressively. The nuclear fusions present the 
ordinary conditions of fusion of the karyoplasm and, ultimately, of the 
nucleoli. This results in the presence in the zygospore of a large number 
of nuclei doubled by copulation. Dangeard here points out the fact 
that the two fusing structures are not to be regarded as gametes but 
as gametangia, being ‘sexual energids ’ further undifferentiated morpho- 
logically. 
In another paper in 1906, Dangeard ( 9 ) takes up the structure and 
development of the Mucorineae. His chief studies were made on the form 
Mucor fragilis because it contains a small number of nuclei. It was only 
after describing the nuclear fusions in Mucor fragilis that Dangeard was 
able to return to Sporodinia and describe the fusions there. The account 
varies but little from that given in previous accounts up to the place where 
nuclear fusions occur. Dangeard describes the nuclear fusions as occurring 
after the endospore has been established, and at the time when the 
protoplasmic portions become vacuolated. 
In the mature zygospore, the vacuolate structure gives way to an 
alveolar structure, in which is contained the oil and other reserve substances. 
The zygospores contain chromatic bodies which are made up of a dense 
homogeneous substance which stains red with the triple stain. These 
chromatic bodies or corpuscles are usually very large, and two or three 
appear in a section. Their position is not constant, and they vary in size 
within the same zygospore. Their mass is without structure, and they are 
contained on the inside of a vacuole. Dangeard likens them to the coeno- 
centra described by Stevens in Albiigo. He describes similar structures as 
occurring in the suspensors, and also in the mycelium. In the older 
zygospores, Dangeard suggests that the large corpuscles numbering 10-20 
are merely mucorine crystals which have undergone reconstruction. They 
have increased in volume and lost their crystalline nature. Dangeard then 
goes into an account of the formation of the membranes of the zygospore, 
which does not concern the immediate problem in hand. 
Lendner ( 23 ), in 1908, recognizing the incompleteness of the reports on 
the fecundation of the Mucors, undertook, in connexion with some other 
work on their morphology, to work out the cytology of Sporodinia . His 
observations on the earlier stages agree with the majority of the previous 
workers. He emphasizes, for the first time, the activity of one of the 
gametes, and describes its penetration into the other. 4 In some rare cases, 
it has been possible to observe a rather large mass which I have considered 
as one of the fusing nuclei, although the density of the protoplasm at this 
time is very great, rendering observation of the nuclei very difficult. . . . The 
middle membrane having disappeared, the protoplasm remains dense along 
