476 
Journal of Agricultural Research 
Vol. XXI, No. 7 
frequently lacked the normal segmentation. These latter relations are 
well shown in Plate 88, A, B, and is further expressed together with 
other relationships in Table IX. 
Table IX .—Measurements on Irish Cobbler plants , grown in uninoculated soil , 
showing the effects of soil temperature upon the development of the various organs 
33 days after planting 
Number of plants measured... 
9-5° C. 
i2°C.a 
Average height of shoots.. (in.). 
Average diameter of shoots 
(mm.). 
. 
2. I 
Average width of leaves (mm.) 
Number of leaves per plant... 
Average number of leaves per 
inch of height. 
15 . 3 ° c. 
0 
0 
00 
M 
21 . 4 ° c. 
A 
O 
O 
2 7 .2°C. 
30.5° C. 
6. 0 
5 - 0 
9.0 
6. 0 
9.0 
5 -o 
4-3 
5-8 
5-0 
4.8 
3.8 
3-2 
7-5 
8.75 
7-5 
7-5 
6- 5 
5 *o 
37 - 5 
38. 0 
32. 0 
26. 0 
17. 0 
14. 0 
4-5 
5 -o 
5 -i 
7.0 
7.0 
6. 0 
1. 0 
.86 
1.02 
1-45 
i *45 
1. 8 < 
diat hihuT^ve' ^ciaWemeasurcmQm' a,ltS *” ‘ he "° C tank WerC iUSt throUEh thc soil but not suffi - 
At 30 0 C. excessive lenticle development resulted on both the under¬ 
ground stems of the growing plant and upon the mother tubers. This 
response, no doubt, appeared as results of the excessive respiration occa- 
sioned by the high temperature of the soil. 
The various abnormal responses were not confined to the soil main¬ 
tained at 30° C. but were found in a much less exaggerated form at 24 0 
and 27 • Both these latter temperatures appeared decidedly unfavor¬ 
able for the continued growth and development of the plant under the 
conditions obtained in the experiments. The plants grown at 9 0 and 
12 0 showed a development which might be considered below normal 
and exhibited more or less spindling shoots, long intemodes, few leaves, 
and slight yellowing. No tendency to direct tuberization was shown as 
was found by Vochting (77) to occur at 6° and 7 0 . On the whole, the 
plants showed the greatest vigor during the latter period of their early 
growth in the soil held at 18 0 and 21 0 . In parallel experiments which 
were conducted on the potato at the same temperatures and in which 
plants were grown approximately to maturity, the soil temperature of 
15 to 18° proved more favorable than any of the higher temperatures 
for the plants to withstand the continued artificial conditions imposed 
in the experiments. 
FUNGI CONCERNED IN PRODUCTION OF EESIONS 
In drawing conclusions from the results obtained from the different 
experiments in which pure culture and sclerotial methods of soil inocu¬ 
lation were used, the question immediately arises as to whether in the 
two cases we are dealing with one and the same pathogen or strains of 
the same pathogen or whether in the case of sclerotia-inoculated soil 
