; 
19161 
GILMAN—CABBAGE YELLOWS 43 
flower, and China aster were added for the same reason. 
None of these latter were capable of infecting the living cab- 
bage plant. 
SUSCEPTIBILITY OF HOST 
That the susceptibility of the host plant must also play an 
important part in this question of inoculation is shown by 
the fact that so few of the cultures gave a perfect (100 per 
cent) infection, although the inoculations were made with 
parts of the same culture on plants from the same pot and 
under as identical conditions as possible. 
Further evidence on this point was also shown when the 
difference in the length of the incubation period of any one 
culture was noted on plants of the same variety and age. For 
example, in the last experiment observations were made daily 
in the greenhouse, and the condition of the plants noted. The 
results of these observations are brought together for a few 
of the cultures in table vt. 
TABLE VI 
RESULTS OF OBSERVATIONS ON INDIVIDUAL SUSCEPTIBILITY AS 
SHOWN BY THE INCUBATION PERIOD UPON INOCULATION 
Number of diseased plants in each pot at the 
various days of incubation 
Culture 
no. 
15 16 17 19 23 40 50 
+. А отказ. 1 2 3 3 3 3 1 
So evo ы Ыс» 2 2 2 3 3 3 
| beo deus gen ЕРТ 2 3 3 3 3 
dE EE ose i 1 1 4 4 4 
5 ыс ли Beret BEBE ER 2 3 3 8 
22,55 SS Ee aes. 1 2 3 4 
Control... EEN ҒАС ХЕ А E ma SE са = 
Thus it is shown that not only were some virulent cultures 
slower in taking effect than others, but that the individual 
plants were markedly different in their ability to resist the 
fungus. Although what constitutes such resistance has not 
been worked out, a little evidence gathered during these in- 
vestigations may well be presented here. 
