MICHIGAN ACADEMY OF SCIENCE. 
207 
The description of the fungus as grown on the agar medium is as 
follows: Sporangiophores upright 1 to 1.5 mm. long and 10 microns 
broad, usually simple, or in some cases branched once and in others very 
irregularly and profusely branched. Sporangia are 60-70 microns in di- 
ameter, round, deliquescent, spiny, the -sporania on the main axis ripen- 
ing first in those cases where the sporangiophore is branched. Columella 
smooth, of a suppressed spheroid shape, 28-38 microns long and 23-36 
microns broad. Spores light green in color, elliptical, 3.3 microns long 
and 2 microns broad. 
Zygospores sometimes formed on sporangiophores, but more often on 
special upright sympodial branching carriers which project above the 
substratum. The zygospores are round 30-60 microns in diameter and 
dark brown in color. The exospore is covered with numerous warts, and 
is almost black in color; the endospore also having warts but being light 
brown in color. 
Gemmae intercallary, usually formed on short, thin sympodially 
branching side branches; at first elliptical, but later rounding up some- 
what and becoming thick walled. The size varies in length from 8-13- 
microns and in width from 13-23 microns. 
The formation of the zygospore is probably best described by refer- 
ring to the accompanying plates. Figure I, Plate I, shows a common 
method of branching of the mycelium just before z 3 r gospore formation. 
It will be seen that the mycelium branches at its tip, one branch being a 
continuation along the axis of the mycelium while the other projects 
upward and arches over toward it. The arching continues until the 
curved branch touches the other one when the walls at the point of con- 
tact are dissolved away and a complete passage way is formed between 
the two branches as shown in Figs. 1 and 2, Plate I. Figure 3 shows 
the part which is to become the zygospore cut off from the copulating 
branches. The time of this cutting off is very variable, taking place in 
some cases when the zygospore is extremely young and in others only 
after the zygospore has taken on the warty character. Figure 7 shows 
an interesting variation in which two zygospores are formed from the 
same large copulating filament. Figure 7, plate 2, shows a mature zygo- 
spore with its characteristic tympanum-like spot where the larger copu- 
lating branch is attached to the zygospore. Under favorable conditions 
a small round spot may be seen where the smaller copulatory branch is 
attached to the zygospore. The method of the branching of the sporan- 
giophore is shown in Figure 1, plate 2, while figure 3 shows the gemmae 
much enlarged. The characteristic shape of the spores is shown in fig- 
ure 5, and figure 6 shows a sporangium much enlarged with the columel- 
la in place. 
REFERENCES. 
A. Fisher. Rabenliorsts Ivrvptogamen — Flora. Die Pilze IV, 1S92 pp 
198. 
P. Vuillemin Bull. Soc. Bot. Fr. XXXIII, 1886, pp. 236 — 238. 
P. Vuillemin. Bull. Soc. Myc. Fr. XIX, 1903, pp. 106-118. 
Botanische Jaresbericht XIV. Jahrgang, I. Ab. 1886, pp. 466, pp. 889. 
University of Michigan, April 20, 1911. 
