308 PovaH: A CRITICAL STUDY OF 
As has already been stated, sixty-six collections of the genus 
Mucor were made. These were studied carefully from uniform 
bread cultures made in the previously described manner, and from 
the data obtained they were tabulated according to their specific 
individuality. In this preliminary arrangement twenty-six dif- 
ferent groups were obtained, which, by careful comparison, were 
reduced to twenty-four groups. Nine of these aggregates were, 
after a careful study, referred to four species, three of which were 
undescribed. Thus the sixty-six collections of Mucor were dis- 
tributed through eighteen species. 
In TABLE I two species, Glomerula repens and Zygorhynchus 
-Vuillemini, have been excluded from Mucor, although Lendner 
includes both Zygorhynchus and Glomerula in that genus. He ex- 
amined specimens of the former only. A study of Glomerula 
repens, from two separate collections, has convinced the writer 
that this species can not be placed under the genus Mucor be- 
cause the hyphae may serve as stolons. For example, if the 
tip of a hypha touches the wall of the culture container, a 
cluster of rhizoid-like hyphae is formed, and often from this 
cluster sporangiophores are developed. Moreover, the general 
habit of growth is unlike that of the species of Mucor. An in- 
crease in lack of sporangia production often results in a cottony, 
dense, sterile mass of buff mycelium. Zygorhynchus, on account 
of its unequal suspensors, not to mention its very slight production 
of sporangia and abundant zygospore formation, should, in the 
writer’s opinion, be kept as a separate genus. 
3. EXPERIMENTAL 
The experiments, in so far as their original purpose is concerned 
proved almost entirely negative. It was thought that striking 
cultural results might be obtained from the experiments which - 
might form the basis for a physiological separation of species. 
Little of this kind was observed. On the contrary, the experi- 
ments showed that the genus Mucor is composed of a physio- 
logically close group of species, exhibiting only minute cultural 
variations. Sometimes these differences were correlated with 
species, but sometimes they occurred sporadically. A concrete 
example of this latter phenomenon was the production of a yellow 
