137 
‘ Biologic Forms' of the Erysiphaceae. 
patches were comparatively large and vigorous, but still remained barren. 
The latter fact was perhaps due to the circumstance that several sapro- 
phytic Fungi were beginning to invade the injured part of the leaf. 
A narrow longitudinal bruise, 3 cm. long and 1 mm. wide, was 
made on three barley leaves in one experiment (No. a 15). By the sixth 
day infection had taken place on all the leaves at the injured place, vigorous 
mycelial patches being visible on the injured translucent cells. On the 
eighth day a few conidiophores were visible. On the tenth day all the 
leaves bore numerous vigorous mycelial patches bordering the sides of 
the bruise. Many of the patches bore numerous conidiophores, which in 
several cases were closely clustered. 
In three experiments (Nos. a 5, a% a 26) forty-five barley leaves were 
bruised with the end of a glass rod, as before, and then exposed to ripe, 
bursting perithecia. In four to six days more or less vigorous patches of 
mycelium (with vigorous lobed haustoria), proceeding from germinating 
ascospores, were formed at the edge of the bruise on 4 en of the leaves. At 
the end of this time the injured tissue of the leaves became more or less 
completely covered by a vigorous growth of saprophytic Fungi, the spores 
of which had been sown with the ascospores. 
Five experiments (Nos. #57, # 63, 031, a 5 2, a 020) were made in which 
barley leaves were nipped hard at the margin with a pair of forceps, causing 
a severe bruise about 4 mm. long and 1 mm. wide.. Twenty-one leaves 
were thus treated, and inoculated on the upper surface. Fourteen leaves 
became infected at the bruised place. On all the fourteen leaves vigorous 
mycelial patches were produced in five to seven days, and after seven to 
thirteen days these bore numerous conidiophores which in some cases 
formed little clustered tufts. 
C Injury caused by Narcotics, etc. 
Experiments were now made in which leaves were exposed to the 
action of ether, chloroform, and alcohol respectively, and then inoculated. 
a. Ether. 
Barley leaves were cut off from seedling plants and exposed to ether 
vapour in a closed Petri dish. In three experiments nine barley leaves 
and three wheat leaves were exposed for 20, 10, and 3 minutes; all the 
leaves proved eventually to have been killed by this treatment. 
In experiment No. a 55, three barley leaves and two wheat leaves 
were exposed for 2 minutes to ether vapour, and then inoculated over the 
greater part of the upper surface. On the twelfth day the two wheat leaves 
were completely covered, over the inoculated part, with continuous patches 
of densely powdery Oidium. On one barley leaf minute patches of 
mycelial hyphae were visible, one patch bearing two conidiophores. On 
