PHYSIOLOGICAL EFFECTS ON PLANTS 13 
Eastern orchards were quite different from those in 
California. With our experiments we did not begin 
with the deciduous trees until the function of the foli- 
age had been performed, namely, late in the fall, just 
previous to the heavy frost. These experiments were 
conducted in late September and early October. It 
made little or no difference to us whether we scorched 
or burned the leaves; our main point was to determine 
what effect the treatment was going to have upon the 
fruit or leaf development for the following season. 
The next practical application of the gas was its 
use for the fumigation of nursery stock. As no pre- 
cise experiments had been condué¢ted in the East, the 
writer began a series in March, 1897, upon young 
apple, peach, nectarine, plum, and pear trees. They 
varied in hight from four to five feet, were thoroughly 
dormant, and badly infested with the San José scale. 
They were placed in a room 4 x 7 x 74 feet, prepared 
for the purpose. A general, miscellaneous lot were 
exposed thirty minutes in gas generated from 0.20 
gramme of cyanide of potassium per cubic foot of air- 
space inclosed. Another lot was exposed to gas from 
0.20 gramme up, through the series formed by adding 
0.05 gramme each time, until 0.50 gramme was 
reached. All the trees of these lots were observed 
very closely for two years. No injury was noticed, 
and not a living scale was ever detected upon them. 
The cyanide used in these experiments was the 98-99 
per cent. pure, while that used at first in the California 
orchards was the old 58 per cent.; this must be taken 
into account when considering the effects of the gas 
on trees and amounts of chemicals used. ‘ 
