1915] HARVEY & ROSE—ILLUMINATING GAS 4l 
experimental tree through a glass tube thrust 0.7 m. into the soil, 
0.6m. from the base of the tree. The rate of flow of gas was 1.5 
liters per hour. The experiment began July 3, and the gas was 
stopped flowing September 2. Except for two or three short periods, 
amounting in all to less than three days, the flow of gas was 
continuous during the two 
months. Thus the soil 
near the tree must have 
received 1.5-2 cubic 
meters of gas. 
The first symptoms of 
injury were manifest July 
14. Leaves of some of the 
young shoots, growing on 
the same side of the tree 
from which the gas entered 
the soil, showed signs of 
wilting. Three days later 
these leaves and others 
had shriveled and died, 
but remained attached to 
the shoots. In some cases 
ohly a portion of a leaf 
was injured. A few leaves 
of older branches also 
wilted, but there was no 
general effect evident 
throughout the tree at that —«*F'ss-8,.9-—Fig. 8 cuamec! ean tia 
: : ex of Hibiscus at base of stem; ; A, con- 
seus ated of eee B, treated with illuminating gas} fig. 0, 
pparently same for lilac; X35. 
unaffected leaves began to 
fall, and finally the tree was free from leaves much before those 
of the controls. In October the tree looked as though it were 
entirely dead, and when an examination was made, after it had 
been removed from the soil, such was found to be the case. A 
general dryness of the tissues was noted, but neither anatomical 
changes nor gas odors were detected in them. 
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