Keene—Studies in Zygospore Formation. 
1195 
STUDIES OF ZYGOSPORE FORMATION IN 
PHYCOMYCES NITENS KUNZE 
Mary Lucille Keene 
The problem of sexuality in the Mucorineae offers an ex¬ 
tremely interesting field of investigation for the physiologist. 
Great differences have been found to exist with regard to the 
production of zygospores and sporangia and considerable ex¬ 
perimentation has been carried on to determine the conditions 
influencing asexual and sexual reproduction. 
The cytological features are very incompletely known. Nu¬ 
merous studies have been made upon Sporodinia grandis, a homo- 
thallic form, with more or less conflicting results. They have 
served, however, to give us some insight into the internal 
changes which occur when zygospore formation takes place. 
With the heterothallic forms, on the other hand, there has been 
little done and the field open here offers many interesting pos¬ 
sibilities. 
Conjugation in the Mucorineae was first described by Ehren- 
berg (1820) in a form ^he termed Syzygites megalocarpus 
(Sporodinia grandis). De Bary (1864) described the process 
of conjugation and zygospore formation in both Sporodinia 
grandis and Rhizopus nigricans. Following this work of de 
Bary, various workers undertook to study and explain the con¬ 
ditions responsible for the production of zygospores. 
Van Tieghem (1876) believed the impoverishment of the 
medium to be responsible for the production of the zygospores. 
Cornu (1876) attributed it to desiccation. Brefeld (1872) in 
an early paper cited cold as an agent but later (1900) he de¬ 
cided that zygospore formation is undoubtedly due primarily 
to some unknown internal cause. Bainier (1883 a and b, 1884) 
