4 Biologic Forms ’ of the Erysiphaceae . 
M 7 
(</) Conidia produced on barley leaves previously exposed 
for 3 minutes to alcohol vapour. 
Experiment No. ao(n. Conidia produced on the tenth day were 
sown at a marked place on a leaf of barley and of wheat. On the seventh 
day a little powdery Oidium - patch was produced on the wheat ; no trace 
of any infection appeared on the barley. 
(2) Ether. 
Conidia produced on barley leaves previously exposed 
for 1 minute to ether vapour. 
Experiment No. <291. Conidia produced on the twenty-first day 
were sown, at a marked place, on a leaf of barley and of wheat. On the 
ninth day the wheat leaf bore, at the marked place, two small quite 
powdery Oidium- patches. No trace of any infection appeared on the 
barley leaf. 
(3) Heat. 
(a) Conidia produced on barley leaves previously immersed 
for 1 minute in water at the temperature of 49*5° C. 
Experiment No. a 029. Conidia produced on the twelfth day were 
sown at a marked place on a leaf of barley and of wheat. The conidia 
used for inoculation had been produced in sufficient quantity to be scraped 
off the barley leaves with the point of a scalpel, and deposited in a little 
heap on each leaf. On the seventh day a large, vigorous, very powdery 
Oidium - patch was produced, on the marked place, on the wheat. The 
powdery mass of accumulated conidia was removed with a scalpel. On the 
tenth day another crop of densely powdery masses of conidia was produced, 
borne by an Oidium - patch 7 mm. long. The conidia were again removed. 
On the fourteenth day a small powdery Oidium - patch was visible, at the 
marked place, on the wheat leaf, which was now nearly dead. No trace 
of any infection appeared on the barley leaf. 
(b) Conidia produced on barley leaves previously immersed in cold 
water and heated slowly to 50° C. 
Experiment No. <2034. Conidia produced on the twelfth day were 
sown, at a marked place, on a leaf of barley and of wheat. By the tenth 
day little powdery Oidiu 7 n - patches were produced, at the marked place, on 
the wheat ; no trace of infection occurred on the barley. 
Experiment No. a 036**. Conidia produced on the fifteenth day 
were sown, at a marked place, on a wheat leaf. On the twelfth day a little 
powdery Oidium - patch was produced at the marked place. 
