KUNKEL: PROMYCELIUM OF CAEOMA NITENS 365 
Caeoma nitens suggests that it is a short-cycled rust in no way 
connected with Puccinia Peckiana and in its life history quite 
comparable to Endophyllum Sempervivi. The perennial mycelium 
lives over winter in the tissues of the host. Cell fusions at the 
base of the chains of aecidiospores produce sporophytic cells from 
which the aecidiospores arise by conjugate division of the two cells 
that fuse. This gives binucleated aecidiospores and intercalary 
cells. The fact that the aecidiospores germinate in a promycelium 
suggests that here, as in Endophyllum, nuclear fusion takes place _ 
in the aecidiospore and we may expect that the sporidia produced 
by the promycelium reinfect the host and produce a mycelium 
with uninucleated cells, thus completing the life cycle. 
If, on the other hand, Puccinia Peckiana is a stage in the life 
history of this fungus, the problem is not so simple and no 
similar case is known among the rusts. 
As was pointed out in the introduction, the fact that sexual 
fusions occur previous to the production of aecidiospores is well 
established. The above described germination of these spores 
makes clear another stage in the life history of this fungus, and 
raises a number of interesting questions regarding its position 
among the rusts. I shall test during the coming summer the 
evidence regarding the connection supposed to exist between 
Caeoma nitens and Puccinia Peckiana, and shall also undertake a 
cytological study of both of these forms. The wide distribution 
and economic importance of Caeoma nitens, its abundant production 
of spores and the ease with which they may be germinated and 
studied makes it a favorable object for class use. It is, therefore, 
highly important that all stages in its life history should be 
thoroughly understood. 
SUMMARY 
1. The aecidiospores of Cacoma nitens on germination regu- 
larly produce a promycelium. 
2. This promycelium normally consists of five cells. The 
stalk cell contains no nucleus, but the other four cells contain one 
nucleus each. _ ; 
3. Each uninucleated cell bears a sporidium on a sterigma. 
4. These sporidia germinate immediately by producing either 
a secondary sporidium or a germ tube. 
