8o 
GEORGE F. ATKINSON 
a large quantity of the aecidiospores of Caeoma nitens Schw. In the 
course of six weeks pustules of Puccinia peckiana appeared on a few 
of the leaves. No further attention was given to observations on 
this rust until June, 1915. 
As a result of Kunkel's studies, I was led to test the germination 
of the aecidiospores in the vicinity of Ithaca, N. Y. In the suburbs 
of Ithaca, on Cornell Heights along Fall Creek Drive, there has existed 
Jor a number of years a rather large patch of the common dewberry 
'{Rubus villosus Ait.), which for several years has been very badly 
-afTected with this rust. Aecidiospores from the leaves were dusted 
on the surface of water in several glass vessels, ranging from 10 to 
20 cm. in diameter. The spores were so numerous that they formed a 
dense orange-yellow layer on the surface of the water. In eighteen 
to twenty-four hours vast numbers of the aecidiospores had germinated 
with typical promycelium and sporidia. Similar sowings of aecidio- 
spores from the same patch of dewberry plants were made during 
the month of June, 191 5, with the same results. 
Some interesting observations were made at that time on the 
germination of some large aecidiospores. These aecidiospores germi- 
nated in two ways. In some cases two distinct promycelia, each 
bearing four sporidia, issued from each aecidiospore. In other cases a 
single germ promycelium issued from the aecidiospore, and at a short 
distance branched into two promycelia each bearing four sporidia. 
Similar large aecidiospores were found to contain four nuclei, while 
those of ordinary size contain but two. We are warranted, therefore, 
in drawing the inference that the four nuclei in the large aecidiospores 
represent two conjugate pairs of nuclei. 
Early in the spring of 191 5, I obtained from a nursery in Geneva, 
N. Y., several young raspberry and blackberry plants free from the 
disease. These were potted and the pots sunk in the ground in the 
partial shade of some trees on the south side of my office. Aecidio- 
spores from the dewberry plants were sown on some of these experi- 
mental raspberry plants, on which new shoots were just appearing, 
many of the aecidiospores falling on the soil close against the stems. 
No evidence of any infection was observed during the season of 191 5, 
either in the form of Caeoma pustules or of teleutospores. In June, 
1 916, however, one new shoot from one of the raspberry plants bore 
several leaves with the caeoma richly developed. Apparently the 
mycelium did not exte lid to other parts of the system and become 
