Electric Currents 71 
premature dropping of leaves and dying of branches occur 
above the affected root. <A characteristic outward sign for 
diagnosis is the darkening and rapid loosening and falling 
of the bark, similar to what occurs in the case of kerosene 
poisoning. 
If the leak is a sudden one and the gas escapes in a large 
quantity, a tree in full foliage may suddenly have its leaves 
droop and turn brown; these hanging on, however, till 
winter winds tear them off; such trees die in short order. 
In some cases trees have been known to have been killed 
by gas in a single night. 
If, however, the leak is slow and small, only a single root 
and its corresponding crown parts may be killed, but, if 
the leak continues and the gas spreads in the soil — which in 
loose soils may go on rapidly for a thousand feet or more, 
— general debility develops and the whole tree gradually 
succumbs. ‘There is practically no recovery for a tree once 
severely poisoned in this way, for the soil is saturated with 
gas, the roots are killed, and it is practically impossible to 
renew the soil. 
Watering, which has been proposed as a remedy, does 
not seem to counteract the poison. If detected in time, 
renewal of the soil, root pruning, and severe cutting back 
may restore the patient. 
Electric Currents. The appearance of trees killed by 
gas is very much the same as that of those killed by light- 
ning or electric currents, the foliage dying and remaining 
hanging on the tree. This takes place not necessarily only 
on trees which show the lightning stroke along the trunk, 
but also as a result of general electric conditions of the 
atmosphere, or of a discharge through the whole tree, with- 
out any apparent actual mechanical injury. 
If the stroke follows a vertical line along one side of the 
