362 KUNKEL: PROMYCELIUM OF CAEOMA NITENS 
and his drawings hardly suggest the promycelial nature of the 
germ tube. Clinton (1) has also studied the germination of these 
spores and gives more than twenty figures, showing them in various 
stages of development, but he failed to find any trace of sporidia. 
He mentions having observed the spores in water cultures during 
two or three days and gives a detailed account of their germination. 
He also observed the germination of the spores on the moist 
surface of young blackberry leaves. 
Olive (7) and Kurssanow (4) have investigated Caeoma nitens 
from the cytological standpoint. They have shown that sexual 
fusions occur in the base of the caeoma and that the aecidiospores 
typically contain two nuclei. 
OBSERVATIONS 
The aecidiospores used in this study of their germination were 
obtained from well infected leaves of Rubus frondosus. The leaves 
were collected in three different parts of Van Cortlandt Park, New 
York City. All of the spores germinated in the same fashion. 
The cultures were made in Petri dishes containing distilled 
water, tap water, and agar media of various kinds. The spores 
were simply dusted over the surface of the medium and generally 
gave a high per cent of germination. The cultures were kept at 
room temperature (about 23° C.). 
The promycelium ordinarily consists of five cells (FIG. I, @), 
four of which bear sporidia. Stained preparations show that the 
stalk cell is without a nucleus and that the other four cells contain 
one nucleus each (Fic. 1, b), thus demonstrating the promycelial 
nature of the germ tube. Frequently the promycelium consists of 
only four cells and in that case each cell is capable of producing a 
sporidium (FIG. I, c). There are also instances where the promy- 
celium consists of less than four cells, but in such cases two or 
more sporidia are generally produced on the same cell. The 
promycelium sometimes consists of more than five cells (FIG. 1, d). 
Five or six sporidia are sometimes produced by the same promy- 
celium, but thisisa very rarecase. In FIG.1 , eis showna basidium 
with sporidia in different stages of development; it also shows one 
sporidium that has fallen off from its sterigma and has begun to 
germinate. 
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