[Vor. 8 
44 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
the various strains. Each tuber was planted in a pot of steril- 
ized soil and placed in the greenhouse. The results are shown 
in table xxx. 
After 4 months all the plants were dug up, and the tubers 
very carefully examined. Practically all those from the sections 
P1, P4, and H presented more or less sclerotia on the surfaces 
showing apparently no difference in color and form. Numerous 
sclerotia were also observed on the stolons. 
TABLE XXX 
INOCULATION OF SEED-POTATOES 
P1 | P4 | P7 | B1| H | B3| Check 
No. seed-potatoes used... aaan. 10 | 10 | 10 | 10 | 10 | 10 | 10 
No. potatoes sprouted. ........ aunan. 8| 9| 9110| 9|]10O| 10 
Ao. HD ION. rero oreet esed 1.11] 241 01-31] 0 0 
No. plants, black speck sclerotia............ 3| 3| 0| 0| 2] 0 0 
No. plants, stem lesion and black speck...... 4| 2|; 0| 0| 3| 0 0 
In pathogenicity as well as symptoms no marked distinction 
between P1 and H was noted. Concerning the relationship 
between P1 and P4 as stated in the section dealing with the 
cultural experiments, these are not considered distinct species, 
but may be regarded as only somewhat specialized in physiologi- ` 
cal and morphological characters. 
P7 is not virulent, although it may induce some secondary 
injury when the plants are physiologically weak. No light is 
thrown on the relationships between P1 and B1, for absolutely 
no infection occurred in the section B1. In general, none of 
these fungi kill the host plant directly under the conditions 
described. 
Experiment 6. (Planting the tubers showing Rhizoctonia scle- 
rotia). —Twenty tubers showing Rhizoctonia sclerotia were 
planted in pots of sterilized soil. The plants were removed 
from the pots and examined after about 4 months. Many of 
the tubers were then covered with sclerotia, but no other symp- 
toms, such as stem lesion, Rhizoctonia scab, ete. were noticed. 
As a matter of fact, the tubers produced in the pots were very 
