Feb. 28, 1916 
Relation of Stomatal Movement to Infection 
1035 
(11). An examination of several hundred slides prepared at different 
times by this method from inoculated leaves has shown that conidia may 
germinate, produce long germinating tubes and yet not penetrate closed 
stomata (fig. 6). On the other hand, wherever penetration was found 
to occur, the stomata were open, and although it has long been known 
that this organism gains an entrance through the stomata, this point 
has never been mentioned. Thiimen (9, p. 50-54) seems to have been 
Fig. 6 .—Cercospora beticola: Conidia germinating on a sugar-beet leaf, but germ tubes not entering or being 
greatly attracted by closed stomata. 
the first to state that a spore which is carried by some means to a green 
and yet not too old, and thereby hardened, beet leaf, is able to germinate 
in the shortest time, penetrate into a stoma, and form a number of hyphae. 
Frank (3) also agrees with this observation, adding that it is character¬ 
istic that the tufts of conidiophores grow out of the stomata. However, 
no mention seems to be made of the stomatal movement necessary for 
host penetration. 
