260 BOTANICAL GAZETTE [OCTOBER 
toward the periphery. The following spring the maple, elm, and 
Euonymus bush showed no signs of life. The lindens produced 
foliage, but the leaves were bleached and smaller than usual. Dried 
cambium and a rich growth of fungi were further indications of 
injury. 
Similar investigations were carried on by SPATH and MEYER (4). 
In one case during the summer a little less than 1%™ of gas diffused 
daily through 17.8%-™ of soil in a wooded plot. The roots of all the 
trees were killed within a few days. During four winter months 
the same amount of gas was allowed to escape into a wooded plat 
of twice the above area. In this case Platanus, silver poplar, Ameri- 
can walnut, and Ailanthus were killed; the maple and horse chestnut 
were greatly injured; while the linden showed no injury. In another 
experiment 0.0185°"-™ of gas was daily distributed equally among 
seventeen trees. The experiment lasted from April 11 to June 27. 
Before May 30 six of the more sensitive trees had died. By June 21 
all the others, with the exception of the rough-fruited maple, had 
slackened their growth. The leaves of the injured trees were a pale 
green or yellow, and most of the younger roots were dead. According 
to the statement of the gas inspectors, their methods were not capable 
of detecting such light leaks as are shown in this experiment. These 
investigators found that when the surface of the soil is compact, the 
gas may travel long distances before reaching the surface. An 
instance is cited of gas traveling from a leak on one side of a street 
to a cellar on the opposite side, where it became evident by an unbear- 
able smell. These investigators concluded that trees are far nas 
sensitive to gas leaks during the winter than during the growth pe im: 
They also found much more rapid injury where the surface ot the 
soil was packed. The small quantity of gas necessary to kill and 
the great distance that gas travels through the soil serve to empha- 
size the danger to which trees are exposed. i GR 
H. EvLenserc (5), besides summarizing the results given 1D 
previous literature, adds the birch to the list of less sensitive te 
J. Bouu (6) grew slips of water willow in water through nie 
Sas was passed. He found that they produced only short roots 2” 
that these soon died, as did also the buds. The twigs themselves 
remained alive for about three months, until, as he believes, the 
