GREENHOUSE AND COLD FRAME FUMIGATION 127 
large house (15,587 cubic feet), one-tenth (0.10) 
gramme cyanide was used. In case of the double 
English violets, infested with plant-lice, slugs, milli- 
pedes, leaf-eating larvee, cutworms, red spiders, etc., 
fifteen hundredths (0.15) gramme was used, and ex- 
posed twenty minutes. All the insects were destroyed, 
excepting a few red spiders, and even these were kept 
down by frequent fumigation. 
Effects on foliage.—The foliage of single violets, 
like California, Princess of Wales, and the like, is some- 
times slightly injured with the stronger dose of 0.15; 
a weaker amount, one-tenth (0.10) gramme should be 
used for these single varieties. Roses, especially the 
younger growths, are very sensitive, and slight injury 
has been noticed even where the smallest dose (0.075 
gramme) was used. Carnations will stand one-tenth 
(0.10) gramme for fifteen minutes; but more careful 
experiments are needed before the gas is generally 
recommended for either carnations or chrysanthe- 
mums. 
Grapes, under glass, in New Zealand, have been 
fumigated at the rate of nine-hundredths (0.09) 
gramme over night, infested with mealy bugs, with 
good results. It has also been used successfully by 
Dr. J. Fisher on tomatoes infested with the white fly. 
He used one ounce cyanide (28.35 grammes) for 
1,000 cubic feet, and left the plants exposed over 
night without injury. The writer fumigated a green- 
house in Maryland in which cucumbers were growing 
and badly infested with the melon louse (Aphis 
gossypit). The house was filled with gas at sundown, 
using fifteen-hundredths (0.15) gramme of cyanide per 
