904 
Journal of Agricultural Research 
Vol. XXXI, No. 10 
more decidedly than those from a part of the same material in which 
the low temperatures were followed by still lower ones. So far as 
these tests go, the writers find that there is no indication that pre¬ 
cooling per se of the teliospores stimulates their subsequent germin- 
ability. On the contrary, there is some indication that the effect is 
rather that of decided variation of the temperatures. This sugges¬ 
tion is further supported by the increases in germination which 
resulted in the tests beginning October 17, apparently as a result of 
repeated sharp alternation of high daytime and low night temper¬ 
atures during a period of three weeks with but two days of rain. 
Eriksson, who seems to have been the first to test the effect of pre¬ 
cooling on the spores of Cronartium ribicola ( 9 ), got a decided reaction 
as a result of his treatment of the spores, but he does not definitely 
attribute it to precooling per se or to variation of the temperature. 
He inclines to the idea that rain just before the spores are collected 
for cooling has a deciding influence in the reaction obtained. 
Table I .—Comparison of the germination of precooled and uncooled telial columns 
of Cronartium ribicola 
Number 
of tests 
Number 
of tests 
Actual germination 
Condition of material at the 
time of testing 
Total 
num¬ 
ber 
of 
tests 
in which 
precooled 
telial 
columns 
germi- 
in which 
precooled 
telial 
columns 
germi- 
Number 
of tests 
in which 
neither 
Precooled 
telial 
columns 
Uncooled 
teJial 
columns 
nated 
better 
than un¬ 
cooled 
ones 
nated 
poorer 
than un¬ 
cooled 
ones 
germi¬ 
nated 
Num¬ 
ber 
Per 
cent 
Num¬ 
ber 
Per 
cent 
Fresh telial columns. 
9 
5 
4 
0 
•525 
1065 
49 
406 
930 
44 
Old telial columns stored in- 
doors... 
11 
4 
5 
2 
95 
1752 
5 
106 
1783 
6 
Old telial columns stored out- 
doors... 
13 
0 
11 
] 
2 
1 
210 
2148 
10 
540 
2163 
25 
* Numerators indicate number of columns which germinated; denominators, the number counted. 
The writers’ results are merely suggestive. The effects of pre¬ 
cooling per se, of decided temperature changes, and of sharp alterna¬ 
tions of temperatures on fresh material, on material stored at cold 
temperatures, and on material stored at warm temperatures should 
be investigated further. 
GERMINATION OF THE TELIOSPORES 
OBSERVATIONS ON THE GERMINATION OF THE TELIOSPORES* 
The telial columns and the teliospores are distinct units, and there 
is no relation between the percentage of telial columns which show 
germination and the number of teliospores per column which ger¬ 
minate. Throughout the tables in this paper the numerators of the 
fractions indicate the number of columns which germinated, while 
the denominators show the total number of columns counted. In 
* The citations in this chapter are arranged chronologically. 
