906 
Journal of Agricultural Research 
Vol. XXXI, No. 10 
That is, it was noticed that germination occurred only around the 
edges of masses of columns. This did not hold in all cases, but was 
frequent enough to attract attention. 
METHODS OF GERMINATION 
The original plan was to germinate the teliospores by placing the 
Ribes leaves, bearing the telial columns, upside down in moist 
chambers until *the teliospores had germinated, and then to scrape 
off the columns for examination, as had been done previously (16). 
However, a series of 29 parallel tests showed that the “floating” 
method of germination described below gave decidedly better results 
than did the moist-chamber method. (See Table II.) In but one 
instance was germination in the moist chamber better than ger¬ 
mination by the floating method. Therefore the floating method 
was adopted and used for practically the entire series of experiments. 
Table II .—Comparison of germination of telial columns of Cronartium ribicola 
by the “moist-chamber” and “floating-on-water” methods 
Number 
Number 
of tests 
Number 
of days 
Number 
Germination 
Ribes species 
of collec¬ 
tions 
on which 
tests were 
made 
of times 
better 
Number 
Per cent 
Americanum: 
Water__ 
2 
4 
4 
4 
204/222 
92 
Moist air.. 
2 
4 
4 
0 
235/530 
44 
Cynosbati: 
Water.... 
1 
2 
2 
2 
93/142 
66 
Moist air... 
1 
2 
2 
0 
48/455 
11 
Glandulosum: 
Water__.... 
2 
3 
2 
3 
343/375 
92 
Moist air... 
2 
3 
2 
0 
69/410 
17 
Nigrum: 
886/1,458 
Water.__ 
4 
14 
5 
13 
61 
Moist air__ 
4 
14 
5 
1 
457/3,000 
15 
Odoratum: 
Water..... 
1 
2 
2 
2 
145/185 
78 
Moist air... 
1 
2 
2 
6 
29/480 
6 
Rotundifolium: 
Water.. 
1 
2 
1 
2 
152/205 
74 
Moist air... 
1 
2 
1 
0 
57/225 
25 
Vulgare: 
Water___ 
1 
2 
1 
2 
172/180 
96 
Moist air.. 
1 
2 
1 
0 
12/120 
10 
Total: 
Water.... 
12 
29 
7 
28 
1,995/2,767 
72 
Moist air... 
12 
29 
7 
1 
907/5,220 
17 
The floating method of germinating spores was not originated by 
the writers (14, 1, 3, 9, 3, 11) * It is apparently an outgrowth of the 
hanging-drop method. Most writers who have used the hanging- 
drop method do not clearly state whether the spores floated on the 
surface of the liquid or were immersed in it in their experiments, but 
a few clearly differentiated between the two (14,1,15,7). Barclay 
(1, 2) seems to be the first to definitely state that he floated the 
spores on the surface of the water. H. H. York was the first to use 
it for spores of Cronartium ribicola. 
In these experiments a surgeon’s cataract knife, with an arrow-head 
shaped, double-edged blade not more than one-fourth inch long, was 
In this paragraph the citations are arranged chronologically. 
