LOCUST POISONING-— TRADE POISONING 



191 



hands smeared with an ointment containing oil of aniseed, with 

 which all utensils used for the poison should also be smeared. 



Arsenic is often preferable to phosphorus, which is difficult to 

 obtain and dangerous to work with. It should be treated in the 

 same way as phosphorus, but it is as well to find the minimal 

 lethal dose for the local rat before commencing rat poisoning on 

 a large scale, and also to be ready with an antidote in case any 

 person indulges in a dose. 



Many rat poisons are known to natives, especially Tylo-phora 

 fasciculata Buch-Ham (Asclepiadeae), Chailletia toxicaria Don 

 (Dichapetalaceae), both of which are used in Africa, and Dianella 

 nemorosa Linnaeus (Liliaceae) in Malacca. 



LOCUST POISONING. 



Arsenic has been used with success by Mr. King, Government 

 entomologist in the Sudan, and others as a poison for killing locusts 

 in the ' hopper stage.' The arsenic is prepared in concentrated 

 form in treacle and is diluted locally. Into the solution so made 

 chopped fodder is placed, and, after soaking, is spread out for the 

 hoppers to eat in desert parts. Spraying has also been used in 

 cultivated areas. Mustard and the usual iron antidote arc handy 

 in case anyone takes a dose of the poison. 



POISONING OF BIRDS. 



Attempts have been made from time to time to diminish the 

 sparrow pest in cultivated areas by poisons — e.g., strychnine— 

 but with doubtful success. 



Palicourea marcgravii {Rubiacecu) St. Hilaire is said to be used 

 for poisoning pigeons. 



TRADE POISONING. 



The trade poisonings are more fully dealt with in the chapter 

 on Dermatitis venenata, but we may mention the following here:— 



Vanilla Poisoning. 



Vanillismus is poisoning by the dried fruit of Vanilla planifolia 

 (Andrews), which causes colic, vomiting, and pains in the head 

 and muscles. Men working with it may suffer from conjunctivitis, 

 fits of sneezing, and a skin eruption called vanilla itch, charac- 

 terized by swelling, followed in a few days by scaling. There is, 

 however, great doubt as to what is the real cause of these symptoms. 

 Probably some of them are due to a mite in the vanilla. 



Lacquer Poisoning. 



Lacquer is obtained from a brown treacle-like balsam, which 

 exudes when incisions are made into the lacquer-tree, Rhus verni- 

 cifera De Candolle. 



