60 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



tion of Libourne, led to a gradual decrease in the dose, which was 

 definitely regulated to 12-20 grammes only per square metre, say 

 24-28 grammes per stock. Dumas' researches showed that even 

 3 grammes per square metre (jL oz. per square yard) were sufficient to 

 attain the object in view. Owing to the support of the Paris- Lyon- 

 Mediterranee (? Eailway), and the Minister of Agriculture, who estab- 

 lished a superior Phylloxera Commission and Vigilance Committees 

 in the districts invaded, carbon disulphide was employed on the large 

 scale. 



The efficacy of carbon disulphide in the struggle against the phyl- 

 loxera was determined accurately, and the conditions under which it 

 acted were determined by the learned researches of Crolas, Marion, 

 and Jaussan. At the present time the utility of carbon disulphide is 

 no longer in doubt ; it has rendered, and renders, undoubted services, 

 and its use has become universal. To give an idea thereof it will 

 suffice to say that, in 1895, 60,000 hectares (150,000 acres) of vines 

 were treated with carbon disulphide. This product is, moreover, 

 destined to render the same services in agriculture and horticulture, 

 and owing to its remarkable insecticide properties it may become, like 

 manures, an indispensable auxiliary to farmers. It is already used 

 against a great number of insects whose larvae live underground at 

 the expense of the roots, and the good results obtained have led to its 

 use against the ravagers of the aerial part of the plant. There, how- 

 ever, its success has not been so great. 



Its method of use varies according to the parasite to be destroyed. 

 The best results are got when an atmosphere containing a dose 

 poisonous to insects and their larvse can be produced. This condition 

 is easily realized underground, in granaries, hothouses, and under 

 tents of impermeable cloth, with which small-sized trees may be 

 covered. In these different cases liquid carbon disulphide is always 

 used, and acts by evaporation. When an asphyxiating atmosphere 

 has to be produced underground, the carbon disulphide is introduced 

 to a certain depth by a pal-injector, which is regulated for the desired 

 dose. In soils favourable to the diffusion of gases, such as those which 

 are not too compact nor too moist, the vapours of carbon disulphide, in 

 a dose of 20 grammes (307 grains) spread within a radius of 30-35 centi- 

 metres (10-12 inches) around the spot where it has been poured. These 

 vapours remain long enough in the soil for the toxic atmosphere to 

 produce its effect. According to the parasites to be got rid of the dose 

 is diminished or increased, and injected to a variable depth. There 

 are cases where the roots of the v'ne descend so deeply that the carbon 

 disulphide must be injected to 80 centimetres (31^ inches), whilst to kill 

 the larvae living a few centimetres from the surface, one does not go 

 down more than 20 centimetres (7-8 inches). To use carbon disul- 

 phide it is therefore necessary (1) To ascertain the exact spot where 

 the parasites to be killed are, first making a trench and making it at 

 about 20 centimetres (7 "8 inches) below the invaded zone. (2) To 

 choose the moment when the soil is in such condition as to allow the 

 diffusion of carbon disulphide vapours into the interior of the mass, 

 whilst at the same time it places the greatest possible obstacles in the 



