‘ Biologic Forms ’ of the Erysiphaceae. 139 
a few minute patches of mycelium, bearing a few small clusters of 
conidiophores. 
c. Alcohol. 
Barley leaves immersed in a 2 °/ 0 mixture of alcohol and water for 
1 hour, hours, and 4 hours showed no signs of being rendered sus- 
ceptible. 
A 10 °/ o mixture was then used. Immersion in this for 42 hours 
proved fatal to barley leaves. In one experiment (No. 7 1 ) three barley 
leaves were immersed for 22 hours. On the eleventh day one leaf bore 
three little clusters of a few conidiophores and a few minute mycelial 
patches ; the two other leaves were killed. In one experiment in which 
six barley leaves were immersed for 16 hours all the leaves were killed. In 
another experiment (No. # 052), however, in which four barley leaves were 
immersed for 19 hours, two leaves only were killed. The two remaining 
leaves were rendered susceptible, and on the eleventh day bore over the 
upper inoculated surface abundant mycelial patches, with hundreds of 
conidiophores. These conidia were sown on an uninjured leaf of barley 
and of wheat, and proved able to infect only the wheat. 
In two experiments immersion for 5 hours was given. In the first 
(No. a 84) six barley leaves were used, and three control barley leaves were 
also inoculated with conidia from the same source. On the ninth day two of 
the treated leaves bore very numerous mycelial patches over the sown area, 
but no conidiophores were produced. The latter fact was perhaps due to 
a sudden spell of very cold weather which lasted during the close of the 
experiment. No trace of infection occurred on the controls. In the other 
experiment (No. a 06) six leaves were inoculated. On the tenth day five of 
the leaves bore very numerous vigorous mycelial patches bearing hundreds of 
clustered conidiophores. These conidia when sown on three uninjured leaves 
of barley and four uninjured leaves of wheat infected only the wheat leaves. 
In six experiments immersion for 4 hours was given, and in every case 
some at least of the treated leaves were rendered susceptible, the infection 
induced being in some cases very pronounced. 
In one experiment (No. a 66) two of the three barley leaves inoculated 
showed on the sixth day (Feb. 26) clear signs of being infected, by the 
presence of numerous flecks of mycelium, with hundreds of conidiophores, 
over the inoculated area. On the ninth day one of the leaves presented the 
appearance of full infection, the upper surface being covered for a distance 
of 2 cm. with small, scattered, powdery Oidium- patches. On the second 
leaf vigorous little patches of conidiophores appeared scattered over the 
surface of the leaf for a length of 4 cm. No infection was visible on the 
third leaf. On the fifteenth day the two barley leaves still presented the 
same appearance of full infection ; on the third leaf a few mycelial patches 
