537 
of carbon is driven into the tube, E, and by pushing a plug, 
J, fills up the chamber, G, whence it is forced out of the steel 
needle, I, through the opening K, into the soil. 
In order to regulate the dose of bi-sulphide of carbon at each 
injection, one or more washers, Z, are strung on the piston rod. 
The pump is so graduated, that each time the pis on is pressed 
down, a dose of 10 grammes (154 grains or 40z.) is injected into 
the ground. In other words, supposing one injection is made in * 
every square yard: 4,840 square yards multiplied by 10 grammes 
equals 48-4 kilogrammes, or 95-5lbs., are injected per acre. With 
one washer or ring added, 9 grammes are injected, or jy less ; 
with two rings 8 grammes only are injected ; and so on, each ad- 
ditional ring added decreasing the dose by 75. 
The apparatus having received a charge of bi-sulphide of 
carbon, is easily thrust into the ground, unless it gets too dry, 
by pressing on the handles, 8, and on the spur P. The knob, N, 
is then pressed down, and a dose of the liquid injected into 
the ground. On removing the needle the operator stops the hole 
left in the soil with his heel, and the volatile insecticide, being 
thus imprisoned in the soil, diffuses through it, penetrates every 
cleft and rent, and reaches the enemy, which it soon suffocates 
The eggs, however, are not destroyed, and a fresh application 
after hatching, and within a fortnight, has to be made to entire y 
rid the ground of the pest. 
According to the degree of intensity of the invasion, one ‘or 
two injections per square yard are made, or, in other words, the 
knob of the piston is pressed down two or three times. 
Between the lines the steel needle is thrust in full length into 
the ground, viz., 8 to 10 inches, but nearer to the stocks half that 
depth is sufficient. 
Bi-sulphide of carbon is used with best advantage in porous 
soils, whilst on heavy clays, or in shallow soils with a clay subsoil, 
at a depth of 10 or 12 inches, its application is not attended with 
the best results, as the insecticide cannot permeate through the 
mass of the ground, and by being brought into direct contact with 
the roots proves injurious to the plant. 
How AND WHEN TO SprRAY. 
Credit is given for much of the information contained in this 
chapter to the contributions of Dr. N. A. Cobb, once Pathologist of 
the Department of Agriculture, Sydney, and published in the 
Agricultural Gazette of N.S.W. 
Mature plants wear an armour of dead cells. Those repre- 
sent the outside skin or cuticle which lines the upper and under 
surface of the leaves, and afford protection to the more tender cells 
which underlie them. 
