TO PUCCINIA GRAMINIS, PERS. 
37 
infected with ALcidium spores from the same source, and three 
plants kept as checks ; both were covered by bell glasses. The in- 
fected plants were, however, kept covered a few days longer than 
the check plants. The ALcidium spores germinated freely in 22 
hours. On the 13th day Uredo appeared upon one of the check 
plants, and on the 14th day upon another ; the infected plants re- 
maining healthy. The experiment was terminated on the 31st day, 
when both check and infected plants were found to have Uredo 
upon them. 
Experiment IV. — On the 9th July one wheat plant was in- 
fected with ALcidium spores from the same source, and a similar 
wheat plant kept as a check. The experiment was conducted in 
the sanae manner as the others. The germination of the ALcidium 
spores was tested by placing some upon a glass slide in a drop of 
water, and keeping them in a damp atmosphere. They did not 
germinate for 48 hours, and then only very feebly. I noted at the 
time “Very faint attempts at germination have taken place ; the 
contents of the slide were placed at 10 a.m. to-day (July 11) on 
the leaves of the infected plant. I think this experiment must fail, 
so weakly have the spores germinated.” Notwithstanding this, 
however, by the 26th day both the infected and the check plant 
had Uredo upon them. 
The hope of demonstrating unequivocally the truth of the he- 
teroecism of Puccinia graminis had by this time become so seriously 
imperiled that 1 determined upon varying my method of pro- 
cedure. One hardly ever sees every individual plant in a state of 
nature, infected with the same parasitic fungus, and it occurred to 
me that by keeping my check plants covered by bell glasses they 
were debilited, and so rendered unduly liable to be attacked by the 
Uredo. I therefore determined to grow my check plants naturally, 
and only to cover my infected plants for as short a time as was 
compatable with the period necessary for free germination to take 
place in the ALcidium spores ; after they had been placed upon the 
leaves. My supply of AZcidium berberidis now failed, and I had to 
procure the fresh spores from Narborough, distanced about nine 
miles by rail, where several barberry bushes grew about a mile 
from the station. 
Experiment V. — On the 26th July ten wheat plants were in- 
fected with ALcidium berberidis spores from Narborough, and ten 
similar wheat plants, grown from the same seed, selected as check 
plants. These latter were never at any time covered by any bell- 
grass, and were planted about six inches apart, some 30 yards from 
where my other experiments had been performed. On the 16th 
day three of the infected plants had Uredo upon them ; on the 25th 
day the experiment was concluded. Five of the infected plants 
had Uredo on them and nine of the checks. 
Experiment VI. — On the 26th July seven wheat plants (two 
of which were only half an inch high with unexpanded blades) were 
inoculated with ALcidium spores from Narborough, and seven wheat 
