HISTORY OF CARBON BISULPHIDE. 59 



Perrault does not admit so great a destructive action on cryptogams. 

 He holds that if CS., acted in that way on insects and cryptogams, it 

 would also act on the useful micro-organisms, which live, in symbiosis, 

 with a great number of our cultivated plants. There exist, in fact, 

 in the soil microbes indispensable to the formation of nitrates, to the 

 decomposition of organic matter ; and microscopic organs which, pro- 

 ducing small nodosites on the roots, fulfil the function of conveying 

 atmospheric nitrogen under an assimilable form (Wilfahrt, Nobbe, 

 Hiltner, and Hellriegel). If Peirault's contention were well founded the 

 fertilizing action of carbon disulphide would be illusory, because that 

 state of things would have to be remedied by applying to the soil a 

 strong dose of nitrogen, not as organic manure, but in the form of 

 saltpetre. It has, however, recently been shown that carbon disul- 

 phide only temporarily affects the bacteria useful to agriculture, and 

 WoUny formulates the results obtained up to now as to the action of 

 carbon disulphide thus :— 



(1) The introduction of carbon disulphide into arable land during 

 the period of vegetation has the effect, according to the quantity ap- 

 plied, of either completely destroying vegetable life, or of causing tem- 

 porary trouble. (2) When the sulphide is applied several months before 

 cultivating the soil, the fertility of the soil is greatly enhanced. This 

 action of the sulphide extends, according to the quantity used, over 

 one or more periods of vegetation, and it is followed, if manure be not 

 employed, by an important decrease in the yield of the tield treated. 

 The lower organisms which play an active role in the decomposition 

 of organic matter and in the formation of nitrates in the soil, as well 

 as the bacteria of the radicular nodosites of the leguminosse, are not 

 killed even by strong doses of carbon disulphide ; their activity only 

 receives a temporary check, to resume afterwards all its energy. 



Use. — History. —Baron Thenard was the first who drew attention 

 to the services which carbon disulphide might render in destroying 

 the phylloxera of the vine, but his experiments, made in 1869, owing 

 to the then defective methods of applying this insecticide, did not give 

 the result expected. The method of application and the doses used 

 play, in fact, a role of very great importance in the success of this 

 treatment, and it was not until after the researches of Monestier, 

 Lautaud, and Ortoman that carbon disulphide gave some good results. 

 In 1873 these scientific observers concluded that carbon disulphide 

 is not injurious, except in the liquid state, when it is brought into 

 direct contact with the roots of plants ; it is necessary therefore, so 

 as to remedy this drawback, to inject the liquid at a certain distance 

 from the plant in such a way that the vapours disengaged form around 

 the roots an atmosphere sufficiently toxic to kill the parasites. "With 

 this end in view they recommended that the carbon disulphide be 

 caused to act from below upwards by depositing this agent in holes 

 pierced to a depth of 80 centimetres (31-i^ inches) ; although based on 

 an excellent principle, the use of carbon disulphide too often caused 

 the death of the vine, for the doses used, which varied from 150-375 

 grammes per stock, were too strong. Experiments by the Montpellier 

 Agricultural Society, due to the initiative of the Viticultural Associa- 



