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will repel the attacks of mosquitos, if only for a short period, is a 

 desideratum in the case of soldiers in malarious countries, the discovery 

 of an effective culicifuge would be of great importance, as troops 

 arc necessarily exposed to risks not incurred by civilians. 



The mosquito used in these experiments was Stegomyia fasciata, F., 

 the choice of which was due to the possession of a West African 

 stock of this species, and to the fact that it can be easily reared in 

 captivity; and though it does not necessarily follow that the value 

 of the preparations tested will be the same against Anophelines in the 

 field as against S. fasciata under laboratory conditions, yet the work 

 may afford a practical comparative guide. The females of this 

 species are renowned for their blood-sucking proclivities, feeding just 

 as well under laboratory conditions as when at libert}^ the season of 

 the year making no difference to either breeding or feeding, provided 

 that temperature and humidity are favourable. 



Of the preparations tested, 12 were prepared with wax, 3 were of 

 a greasy nature, 3 were Uquids, and 3 were prepared as soap, and it 

 was found that those made up with grease or as soft soaps had the 

 advantage in ease and economy of appHcation, though waxy prepara- 

 tions have a great advantage as regards endurance. Fluids, especially 

 highly volatile ones, require much more skill and care in application 

 if waste is to be avoided, while hard soaps are best applied by first 

 wetting the skin, and they suffer from the fact that perspiration will 

 remove them more readily than it does either wax or grease. 



An ideal culicifuge should (1) spread easily so as to enable it to 

 be quickly and evenly applied over the exposed area, while (2) it must 

 be of such a consistency that it will adhere firmly to the skin, and 

 (3) retard volatilisation. The individual tastes of persons in regard 

 to odours are varied and their disHkes so intense that it is difficult 

 to advise as to the best of a number of preparations giving approxi- 

 mately equal degrees of protection. Among troops and others 

 compulsorily subjected to measures of malaria control, a preparation, 

 the odour of which is greatly disliked, might fail because the majority 

 would not apply it, or would do so indifferently, a difl&culty that 

 might be met by adopting two classes of preparations. 



In testing a preparation, the arm from wrist to elbow was coated 

 with it as evenly as possible, the hand being covered by a rubber 

 glove, so as to restrict the bites to the forearm. The arm was 

 then covered by the sleeve for 15 minutes to allow of some 

 volatilisation, before exposure in the cage for 10 minutes. In a 

 second series of experiments the procedure was the same, except 

 that the arm, after treatment, was exposed to the air for from 2-5 

 hours before insertion in the cage. Each test was controlled by insert- 

 ing, after a short interval, the other and untreated arm in the same 

 cage. 



In the first series of trials 8 preparations out of a total of 22 gave 

 satisfactory results. Their active ingredients were oil of cassia and 

 camphor ; oil of cassia and peppermint ; oil of eucalj-ptus and 

 citronella with phenol ; crude naphthaline (coke oven) and camphor ; 

 crude " parasitox " ; light wood oil ; oil of turpentine ; Lawson's 

 anti-mosquito compound. None of the preparations gave complete 

 protection when tested more than 2 hours after application, the most 

 efficient being oil of cassia and camphor, oil of turpentine, oil of 



