Jan. 15, 1925 
Further Studies on Toxicity of Extracted Onion Juice 177 
that in the controls there was a reduc¬ 
tion in viability and vitality in spores 
of both species as the culture aged. 
1, in which the average length of germ 
tubes of the different cultures is com¬ 
pared. It thus became evident that. 
HUMBER OF DROPS OF ON I OH JUICE 
Fig. 1.—Upper graph represents the growth of sporelings of Colletotrichum ctrcinans and the lower graph 
the growth of Botrytis allii from cultures of different ages, when exposed to various concentrations of 
volatile onion oil. See data in Table I 
This reduction in vigor is correlated 
with a diminished resistance to the 
volatile toxins from the onion. This 
fact is especially emphasized in Figure 
with a given comparative series, spores 
as nearly uniform in vigor as possible 
should be used and preferably those 
from very young cultures. 
