in the Brontes and their Brown Rust . 289 
and employed all care in the selection of mature spores from 
unexhausted leaves. 
These series differ from the preceding, further, in that the 
infections were always made on the flat upper surface of the 
leaf, the stomata being more numerous there than on the lower 
surface. In the later cases I also recorded the heights 
of the seedlings employed, to see if that factor was important, 
and used fewer seedlings in the pots, in order to get better 
root-development. 
TABLE XVII. 
Exp. Nos. 727 and 728 , June 24 . Pot plants — -‘seed’ sown June 10 
kept carefully under cover in green-house, plants bright green but some- 
what drawn. Spores good. In the series No. 728 the spores were 
from another source, and proved to be vigorous and germinating well. 
Expt. 
No. 
Species. 
Origin of 
spores. 
No. of 
plants. 
No. in- 
fected. 
No. su 
Wy 5 
cceeded. 
July 1 2 
Results. 
727 
B. velutinus 
B. sterilis 
24 
3 
0 
0 
None 
99 
B. maximus 
99 
24 
3 
0 
0 
99 
99 
B. madritensis 
99 
24 
3 
0 
0 
99 
99 
B. commutatus 
99 
24 
3 
0 
0 
99 
99 
B- arvensis 
99 
24 
3 
0 
0 
99 
99 
B. secalinus 
24 
3 
0 
0 
99 
99 
B. interruptus 
99 
24 
3 
0 
0 
99 
99 
B. racemosus 
99 
B. sterilis 
24 
3 
0 
0 
99 
728 
B. velutinus 
10 
3 
0 
0 
99 
99 
B. maximus 
99 
10 
3 
0 
0 
99 
99 
B. madritensis 
10 
3 
0 
0 
99 
99 
B. commutatus 
99 
9 
3 
0 
0 
99 
9 9 
B. arvensis 
99 
10 
3 
0 
0 
99 
99 
B. secalinus 
99 
10 
3 
0 
0 
99 
99 
B. interruptus 
99 
10 
3 
0 
0 
99 
99 
B. racemosus 
99 
10 
3 
0 
0 
99 
Table XVII shows once more how incapable are spores 
from B. sterilis of infecting Bromes from the Serrafalcus group, 
but we must not overlook the fact that B. madritensis also 
escaped. 
The three series Nos. 747, 752, and 754 (Table XVIII) 
were instituted to test a different set of Bromes. As before, 
pots of seedlings a week old were employed and the infection 
was at the tips of the spears, the spores being laid on in wet 
