134 Salmon . — Further Cultural Experiments with 
were, however, barren, with the exception of one patch which bore four 
conidiophores. 
In the first experiment (No. io) in which ascospores were used, one 
wheat leaf and one barley leaf, both just removed from seedling plants, 
were placed by the side of a barley leaf out of which sings had eaten large 
pieces 1 . The three leaves were exposed for 48 hours to inoculation from 
ripe, bursting perithecia. By the third day the leaf which had been injured 
by slugs was yellow and translucent in its upper half, and hundreds of 
ascospores could be seen germinating on its surface. On the sixth day the 
wheat leaf was covered with very numerous powdery Oidium - patches ; the 
uninjured barley leaf was covered with hundreds of ascospores which had 
germinated but failed to produce infection ; the barley leaf injured by slugs 
was infected with numerous vigorous little patches of mycelium, some of 
which bore a few young conidiophores. The fertile patches were all 
situated along the edges of the bitten places ; at a distance of 1-2 cm. 
from the places of injury several little barren patches of a few straggling 
hyphae occurred. 
In the second experiment (No. 11) four barley leaves, out of which 
slugs had eaten portions here and there, thus producing numerous irregu- 
larly shaped holes, were exposed for 48 hours to ripe* bursting perithecia. 
On the sixth day two of the leaves bore each several little patches of 
mycelium proceeding from germinating ascospores situated close to the 
edges of the bitten places. The patches were mostly barren, but a few had 
produced one to three conidiophores. On one leaf an ascospore situated at 
a distance of 2-5 cm. from the edge of a hole had germinated and produced 
a few mycelial hyphae and two young conidiophores. 
e. Injury by Pressure. 
In the first series of experiments the following apparatus was used. 
A glass tube was supported vertically in the clamp of a stand placed on 
a table. A wooden rod of a slightly smaller diameter than the tube was 
passed through the latter, and thus kept upright. The upper end of the 
rod carried a cork disk, on which the weight used was placed ; the lower 
end had a flat surface of 7 mm. diameter, with a rounded edge to avoid 
cutting the leaf. The leaf was placed flat on a glass slide on the table, 
and the end of the wooden rod rested on it. 
Three experiments were made in which the weight 2 used was 9*5 oz. ; 
the pressure was applied to three barley leaves, attached to growing plants, 
for 24 hours. The leaves were then cut off, and placed in a Petri dish ; 
conidia were then sown on the bruised place. In the first experiment 
1 The two holes made by the slugs measured 2.5 cm. x 3 mm., and 1.5 cm. x 1 mm. 
2 Including that of the rod and cork disk. 
