Keene—Studies in Zygospore Formation. 1211 
there are stainable contents. When fixed with Flemming’s 
solution these areas are blackened by the osmic acid and require 
considerable bleaching before they are clear. They are responsible 
for the zonate appearance of the zygospore at this time (fig. 13). 
The zygospore becomes more and more vacuolate, the groups 
of nuclei become separated, and the disorganizing nuclei may be 
found distributed throughout the zygospore (PI. II, fig. 12). 
As the vacuolate condition increases the center of the zygospore 
becomes quite sponge-like in appearance. The bluish-staining 
bodies enlarge and begin to appear more or less reticulate (PI. 
Ill, fig. 15). They are identical with the bodies described by 
the writer in Sporodinia grandis and are undoubtedly associated 
with the formation of oil. They do not seem to play as prom¬ 
inent a part in the maturation processes in PJiycomyces as they 
do in Sporodinia. It may be that the protein material just de¬ 
scribed replaces to some extent, as reserve material in Phycomy- 
ces, the oil that is so plentiful in Sporodinia. 
The literature referring to the possible relationship between 
these structures associated with oil production in the Mucorineae 
and the elaioplasts described by many workers, has been reviewed 
by the witer in a previous paper (1914). The elaioplasts or 
oil plastids, according to these various investigators, are bodies 
set aside by the protoplasm for the secretion of oil. 
In Sporodinia the oil plastids arise as very small globular 
bodies. When first formed they appear as vacuoles with stained 
contents but careful study of them under high powers of mag¬ 
nification shows a coarse reticulation with a more or less homo¬ 
geneous center. As they increase in size, their reticulate nature 
becomes more and more apparent. A coalescence between them 
takes place, apparently as the result of crowding, and in the 
mature zygospore there may occur from one to three of these 
plastids but usually only one large one is present 
In PJiycomyces these reticulated bodies, as already described, 
appear to originate at various places through the zygospore, 
being most apparent toward the margin. Oil is associated with 
them from their earliest appearance. As the zygospore matures 
these plastid-like bodies become vacuolate, enlarge and assume 
the appearance of definite cell structures. In the older zygo¬ 
spores studied, numerous small'plastids were still to be found 
toward the periphery, but, as indicated in the accompanying 
