210 THE JOURNAL OF BOTANY 
These facts seem to suggest that we may find in the capability or 
incapability of the haustorium to carry on life in the cell of the 
host-plant—which may mean its power to make use of the available 
cells of the host-plant, into which at short intervals they send 
large lobed haustoria. In a few days conidiophores are produced 
on these hyphae. Similarly, but to a much less degree, the pro- 
hypha from the appressorium. No formation, however, either of 
; rapt some enzyme,—then a 
slight variation favourable to the fungus might be sufficient to 
have been observed of “ subinfection.”” On the other hand it may 
be that the explanation of cases of *‘subinfection”’ is to be found 
in the power possessed by an individual spore here and there 
among the spores of a given “biologic form” of being able to infect 
a host-plant which as a rule is immune to the attacks of the fungus 
in question. 
A few remarks may be made on the 
spores, the period of incubation, &c. 
Up to May 7, when the supply of the fungus became exhausted, 
the perithecia on the leaves of barley, which had been kept dry in a 
box throughout the winter, still contained only asci full of granular 
protoplasm without any trace of ascospores. These perithecia, 
e been laid for four days on damp 
germination of the asco- 
filter-paper, produced ripe ascospores. 
If unripe ascospores—eyen sometimes those which are found 
free within the Perithecium on opening it—are exposed to water, 
they are almost immediately destroyed, the wall of the spore split- 
ting and breaking up, and the cell-contents being expelled into 
the water, with the result that no trace of the spore remains. 
Galloway has observed the same behaviour of the ascospores of 
Uncinula necator (Schwein.) Burr. on the perithecium opening in 
