18 FUMIGATION METHODS 
lows: I had fully expected that the gas would badly 
injure the trees above 0.75. In fact, no apple trees 
were injured in the least, even when exposed to 1.45 
grammes, or about six times the normal strength, 
FIG. 2—OGON PLUM TREE, FUMIGATED WITH THREE TIMES 
NORMAL DOSE 
excepting one variety, Northern Spy. I can not ex- 
plain why this was more susceptible to the gas in this 
test than the others, as it is naturally a hardy tree, 
and its resisting properties should be as great as Beu 
Davis or any of the other varieties treated. The 
Lo Sie at 
