164 THE JOURNAL OF BOTANY 
Two control leaves, of twelve, bore small Oidium patches with a 
powdery mass of spores. No trace of infection occurred ,on any of 
the plants of the wheat or rye. 
In the foregoing experiments it appeared almost certain that 
the infection of the control leaves of the barley was due to the 
inoculated ones, in the rapid growth of these young seedlings, 
rushing against them when the plants were confined in the glass 
beakers. In such circumstances the ascospores contained in the 
drops of moisture standing on the inoculated leaves would fall on 
to the control leaf brushing against it. To obviate the possibility 
minute flecks of mycelium, in one case originating exactly from the 
round an isolated crushed perithecium; the third had a minute patch 
of mycelium bearing a few very young conidiophores. ll the 
ree 
of 
young leaves of the control plants, doubtless due to infection from the 
conidia. ace of infection occurred on the rye. 
In Exper. no. 7 (April 8) no special precautions against the 
rubbing together of the inoculated i 
taken. Four leaves of barley and three of oats were inoculated, 
Inoculated leaves on April 8th. On April 9th the second inoculated 
leaf bore five small flecks of mycelium, two of which were producing 
groups of young conidiophores. On April 11th the patches on the 
each two patches of mycelium with powdery masses of spores; the 
rd ix af bore also two very powdery patches, one 
measuring 6 x 4 mill.; two control leaves bore patches of mycelium 
with po ‘masses of spores. On April 16th all of the four in- 
oculated leaves were infected, and bore Oidium patches with powdery 
masses of spores. No trace of any infection appeared on the oats 
_ during the course of the experiment. 
