FUMIGATION WITH CARBON BISULPHID 265 
varies considerably with the amount of the dose, the 
temperature and humidity of the soil, and other con- 
ditions. It has been found more satisfactory to employ 
smaller and more frequent doses rather than a few 
Jarge ones. A dose of 5 or 6 grammes, '/, to '/, ounce, 
is believed to be thoroughly effective through a radius 
of from 12 to 20 inches, though it may penetrate much 
farther than that. ‘The general rule is to make three 
injections per square meter, nearly 1'/, square yards, 
in light soils, and four injections in heavy soil. The 
holes should be at regular intervals, so as to cover the 
ground evenly, and never nearer than one foot to the 
base of the vine. To be effective all the ground must 
be treated. 
On account of the liability of injuring the vines it 
has been found best to make the treatment in two small 
applications, separated by an interval of from six to ten 
days. This decreases the density of the vapor, but 
continues its action for a much longer time. It 
removes the danger of injuring the vines, and gives 
even better results upon the insects than would be 
obtained by one large dose. The total amount of car- 
bon bisulphid to be used should be divided into as 
many equal parts as there are injections to be made. 
The holes for the second treatment should be inter- 
mediate between those for the first. The depth of the 
holes will depend somewhat upon the depth and per- 
meability of the soil. The average depth is about one 
foot. Holes 16 inches deep are desirable on very 
permeable soil. 
Lreatment may be applied at any season of the year; 
but, as it is followed by a slight check in growth, it 
