180 
Joumal of Agricultural Research 
Vol. XXX, No. 2 
germination increases up to about 20° 
C. and then decreases, while growth 
increases to about 27°, then declines 
abruptly. It is to be expected that the 
volatilization of the oil would grad¬ 
ually increase with the temperature up 
to a much higher degree. A marked 
difference in the rate of depletion of 
volatile toxins in expressed onion juice 
held at high and low temperatures is 
lower temperature the volatile toxins 
were still distinctly evident after 22 
hours. The dissolved toxins persisted 
apparently until fermentation by con¬ 
taminating organisms had reached an 
advanced state. 
In view of this evidence that the 
rates of volatilization of the oil varies 
greatly from 10° to 25° C., it is to be 
expected that the temperature at 
shown in Table IV. Juice from a com¬ 
mon source was divided into two lots 
immediately after extraction; one lot 
was placed in the ice box, the other in a 
constant temperature incubator at 25°. 
Tests with juice from the two lots at 
given intervals show that at the higher 
temperature the volatile toxins disap¬ 
pear within a very few hours and before 
any evidence of bacterial fermentation 
was noted. In the juice kept at the 
which spore germination tests are 
made may influence the results. The 
extent of this influence was not as 
great as might be expected. Several 
experiments were conducted in which 
various amounts of onion juice were 
placed in constant temperature in¬ 
cubators over a range of 10° to 28°. 
Evidently the lowering of temperature 
had sufficiently similar retarding effects 
upon volatilization of the oils and upon 
