360 Wisconsin Academy of Sciences, Arts, and Letters. 
Moreau (1911a) and 1911b) in describing cytological studies, 
especially in zygospore formation, of species of Mucor, Zygorhyn- 
chus, Circinella, Rhizopus and Sporodinia states that a nucleus of 
these mucors consists of a chromatin nucleole, a nucleoplasm, and 
a nuclear membrane. The nucleole, is either centrally, eccen¬ 
trically, or laterally placed. In some cases in Mucor a centrosome, 
chromatic in nature, is observed on the external surface of the 
nuclear membrane. In the columella of Rhizopus he finds a 
modification of the nucleus in that there is no nuclear membrane 
and the nucleus consists simply of a homogeneous body. According 
to Moreau, the nucleus divides mitotically in the vegetative hyphae 
and in the zygospores of the forms studied. The process of mitosis 
is inaugurated by the disappearance of the nuclear membrane and 
of the nucleole. No other stages characteristic of prophases are 
described. He describes an equatorial plate stage in which double 
chromosomes are borne on a straight spindle, terminated at each 
pole by a centrosome. He describes and figures a later stage in 
which two daughter chromosomes are in process of moving toward 
each pole. Stages in the reorganization of the daughter nuclei 
are not described. In the zygospore, the mitotic nuclear divisions 
take place, according to Moreau, as if activated by the mixing 
of the protoplasm from the two fusing gametes. He also describes 
a form of amitotic nuclear division of the homogeneous nuclei 
in the columella of Rhizopus. In Mucor, following the nuclear 
divisions in the young zygospore, the nuclei fuse in pairs, giving 
rise to a large number of fusion nuclei. A number of nuclei fail 
to fuse and later disintegrate. In Zygorhynchus the nuclear dis¬ 
integration takes place before fusion, and in the zygospores of this 
form, only two fusion nuclei are formed. The fusion nuclei of all 
the forms studied by Moreau are similar in structure. Each con¬ 
tains a single large nucleole. He states that the fusion nuclei per¬ 
sist in the mature zygospore and form the basis of the nuclei of the 
thallus arising from the germination of the zygospore. 
Moreau (1913) has published the results of very extensive cyto¬ 
logical research of a large number of the Mucoraceae. These later 
results are in accord with his previous work. In the case of 
Phycornyces he states that he saw clearly stages in the fusion of the 
nuclei in the young zygospore at the time the spiny exospore was 
being formed. The fusion of the nuclei in the zygospore, of those 
forms for which he describes the process, consists in the fusion of 
the two membranes at the point of contact, thus forming one 
