2 



period; on large guavas sometimes two or three months. The 

 effect of pouring carbon bisulphid on Crotalaria was to cause 

 the death of the plant, root and branches, within four to ten 

 days. The plants remain green, and apparently normal, until 

 shortly before death, when the leaves suddenly turn yellow 

 and shrivel up. If the plants are then carefully removed from 

 the soil it is found that all of the root-system is dead and the 

 inner tissues of the roots and lower part of the stem are brown, 

 or otherwise discolored. 



Lantana bushes, about two inches in diameter, died within 

 seventeen to thirty-two days after the application of carbon 

 bisulphid. About the same length of time was required for 

 the destruction of Oi. Young prickly-pear plants, about two 

 feet in height, v/ere found to be exceedingly sensitive to car- 

 bon bisulphid. In some cases, the plants fell over on the ground 

 within twenty-four hours after being moistened with the 

 liquid; and in other cases, were dead within two days. 



AYith guava, the effects of carbon bisulphid were not mani- 

 fested for a much longer period, in some cases even not for 

 two or three months. Finally, however, in all but two cases 

 the leaves turned yellow, withered up, and the plant died. The 

 dead and dying trees were dug out and the roots examined. 

 In every case the roots were found to be dead to the tip and 

 their whole tissue discolored. In one case, the guava tree was 

 over six inches in diameter at the base. 



Apparently, the effect of carbon bisulphid, when applied 

 directly to the stems of plants, is due to artificial freezing. As 

 is well known, the liquid volatilizes almost instantly and cools 

 the surface so suddenly that the living bark is destroyed. It 

 was found to be a simple matter to produce ice at noon on hot 

 days on the surface of guavas and other plants by slowly drip- 

 ping carbon bisulphid along the trunk. The death of large 

 guavas from an application of a small quantity of carbon 

 bisulphid to the base of the trunk, a few inches above the 

 ground, can hardly be attributed entirely to the freezing effect. 

 It seems also to exercise a poisonous action, otherwise it would 

 be difficult to explain the complete destruction of the roots to 



