BRIEFER ARTICLES 
DEVELOPMENT OF THE ZYGOSPORE OF RHIZOPUS 
NIGRICANS 
(PRELIMINARY NOTICE) 
In growing Rhizopus nigricans for laboratory use, there was produced 
an unusual abundance of zygospores. This supply of material, and the 
increasing interest in the Mucorales in general, made it seem worth 
while to investigate the development of the zygospore of this species. 
Since completion of the investigation is temporarily delayed, the results 
so far obtained seem to be of sufficient interest to warrant the publication 
ofa preliminary account. 
There is a streaming of protoplasm with nuclei into the young 
suspensors, followed by a denser accumulation at the contact ends of 
the suspensors. 
Before the gametangia are cut off, there appears a difference in the 
density and staining capacity of the protoplasm of the two suspensors, 
and this difference persists until the zygospore is mature. 
The walls, cutting off the gametangia from each other, may not 3s 
formed simultaneously, and in each wall there is left a central pore. 
The wall which separates the gametangia from each other often thickens 
considerably before disintegration, and fragments of the thickened wall 
may be found in quite old zygospores. In the majority of zygospores 
the wall breaks down before any thickening occurs. In the late stages 
of the zygospore there is developed by the protoplast a thick, colorless, 
echinate coat, from which the brown coat may be removed, leaving the 
zygospore intact. 
The many nuclei from each gametangium increase in size after the 
disintegration of the wall. All the nuclei except two disintegrate, and 
these two nuclei are imbedded in a coenocentrum. Preparations were 
submitted to Professor F. L. STEVENS, and he also identified this body 
as being like the coenocentrum of Albugo. There are indications that the 
coenocentrum has its origin at the point of contact of the two suspensors 
before the gametangia are cut off; but this needs further investigation. 
Neither fusion nor division of the nuclei has yet been observed. It is 
believed, however, that the two nuclei, left in the coenocentrum, fuse. 
From this stage to maturity many changes occur in the appearance of 
67] : [Botanical Gazette, vol. 53 
