44 R. GKEIG-SMITH. 



Oberlin in Alsace and Girard in France showed that the 

 direct treatment of a soil with the volatile disinfectant, 

 carbon disulphide, resulted in a pronounced increase of the 

 crop. The disinfectant was employed to kill phylloxera, 

 and the treatment was as successful as it had been in 1875 

 when Kiihn used it to check nematodes infecting root crops. 



It was not the destruction of the insect pests that caused 

 attention to be paid to the action of the disinfectant, but 

 it was the fact that the crops were increased after the 

 treatment. It was also shown that carbon disulphide cured 

 the soil-sickness of the vine, thus enabling vignerons to 

 re-establish a vineyard affected with sickness without 

 having recourse to fallowing the ground or growing other 

 crops until the sickness had disappeared. 



Soil-Sickness. 

 That carbon disulphide could cure soil-sickness rather 

 confirmed the idea that, as there was generally a sufficiency 

 of fertilising material in such soils, the disease was due to 

 the activities of moulds and bacteria. But Koch in 1899 

 €ame to a different conclusion. He found that treatment 

 of the soil, with carbon disulphide or with steam, favoured 

 the subsequent growth of the vines in vine-sick soils. The 

 substances responsible for the disease are apparently either 

 soluble in water or are suspended in it, for extracts of sick 

 soils are able to convey a certain degree of sickness to 

 healthy soils. If the extract is heated, no injurious results 

 are obtained. Although the action of steam upon the soil, 

 or of heat upon the extracts, indicates a probable biological 

 cause, and that the action of carbon disulphide is prob- 

 ably to alter the relations of the groups of the micro-flora, 

 yet Koch 1 considered that the carbon disulphide directly 

 stimulated the plant, much after the manner of the stimu- 

 lation exerted by the copper-lime spray in the treatment 

 of vines and potatoes. 



1 Cent. Bakt. 2 te, 5, 660. 



