3 



their tips, in some instances, six or eight feet from the point 

 where the carbon bisulphid was applied. It was found, for 

 example, that gnava bushes would live for five to seven months 

 after the bark and cambium had been entirely removed from 

 the surface of the ground up to a height of two feet. More- 

 over, the destruction of the bark at the base of the trunk by 

 concentrated sulphuric acid was not sufficient to cause the 

 death of the guava bush for about six months. Apparently, 

 therefore, carbon bisulphid causes the death of plants by its 

 freezing effect and also by a poisonous action. 



The use of carbon bisulphid for destroying underground 

 insects is a familiar practice. It may be interesting, therefore^ 

 to inquire what effect, if any, the extensive use of carbon bisul- 

 phid may have upon the soil and its adaptability to cultivation. 

 It is well known, for example, that the application of carbon 

 bisulphid to the soil around fruit trees and other plants has 

 no injurious effect upon the plants ; in fact, ^Hiltner and 

 Stormer have shown that carbon bisulphid reduces denitrifica- 

 tion and the fixation of nitrogen. Similarly, '^Heinze demon- 

 strated that carbon bisulphid promotes the activity of nitrogen- 

 fixing organisms. In experiments carried on by Nobbe, the 

 yield of peas, and various other crops, was increased as a result 

 of the application of carbon bisulphid and the plants absorbed 

 more ash and nitrogen. ^Henry found that when 400 cc. of 

 carbon bisulphid per square meter was injected into the soil 

 about locust trees, beneficial effects upon the growth of the 

 trees were observed for several years. On the other hand, 

 heavy fumigation with carbon bisulphid has frequently proved 

 injurious or fatal to young fruit trees. In a series of experi- 

 ments by -^Oberlin, carried on for eighteen years, in treating 

 grape Fliylloxera, it was found that carbon bisulphid had a 

 remarkable effect in increasing the yield of grapes. AYhen 

 other crops were rotated with grapes, for example, legumes, 



1. L. Hiltner and K. Stormer, Arb. K. Gesundheitsamte, Biol. Abt. 3 



(1903) pp. 443-545. 



2. B. Heinze, Centbl. Bakt, etc., 2 Abt. 16 (1906) pp. 329-358. 

 S. E. Henry, Bui. Soc. Sci. Nancy, 3 Ser. 2 (1901) pp. 27-33. 



4. C. Oberlin, Jour. Agr. Prat. 59 (1895) pp. 459-464, 499-503, 535-540. 



