TO PUCCINIA GRAMINIS, PERS. 
39 
day two more, on the 31st day one more. At this time the ex- 
periment ended, and Mr. Du Port reported that patch No. 1 had 
three plants in it with Uredo upon them, but that patch No. 2 had 
not a single sound plant in it. 
Experiment XII. — 15 wheat plants grown in my garden from 
one of the best samples of last year’s wheat that had been offered 
in the Lynn Market, were on the 11th August infected with 
sEcidium from Narborough. I purposely kept this sEcidium 62 
hours in a damp atmosphere in my study, and used the water upon 
which the spores had abundantly fallen, as well as the spores them- 
selves, for infecting the wheat plants. On the 17th day three 
plants developed Uredo , on the 20th day six more, on the 22nd day 
one more, on the 23rd day two more, making a total of 12 infected 
plants out of 15, which developed the Uredo in the course of 23 
days. Of the 15 check plants seven only were diseased. 
Experiment XIII. — The thirteenth and final experiment was 
conducted upon a totally different principle. The seed wheat was 
poisoned by steeping it in a solution of cupric sulphate ; and 
the ground in which it was planted was watered with a solu- 
tion of carbolic acid in water. Two bell glasses thoroughly dis- 
infected with carbolic acid and the copper solution were placed 
oyer both the patch to be used as check plants, and over the 
pots containing plants to be infected. These bell glasses were 
never touched until the plants were large enough to infect. On 
the 20th August six were inoculated with jEcidium spores from 
Narborough. A few days later, purposely choosing a day when 
there was no wind, the check plants were reduced to six. The 
bell glasses were not again removed until the 20th day, when 
both patches were rapidly but thoroughly examined and found 
free from Uredo. The glasses were replaced, and the plants re- 
examined on the 30th day. These were then finally removed 
and the plants thoroughly examined, but no trace of Uredo found 
upon either the infected nor upon the check plants. 
The result of these 13 experiments may be thus summarised : — 
Seventy-eight wheat plants were infected with the spores of 
sEcidium berberidis and 98 similar wheat plants kept as check 
plants against them. Of the infected plants 76 percent, developed 
Uredo in an average of 24*4 days. While in the same period 
70 per cent, of the uninfected plants became spontaneously attacked 
by Uredo. One experiment only (No. 2) out of the 13 was 
wholly in favour of the theory, and that lasted only 23 days. Still 
6 per cent, more of the infected plants took the Uredo than of the 
uninfected. This is a very small portion, far too small in my 
humble opinion to constitute convincing evidence. I believe, how- 
ever, that it can be accounted for by my own negligence in not 
thoroughly cleaning the bell glasses before using them to cover 
fresh plants. Had the last experiment (No. 13J, however, proved 
favourable to the theory I should have regarded it as being much 
more worthy of acceptation than I can now do. It is only after 
