636 THE ANIMAL PARASITES OF MAN 



brush which furnishes shelter to the mosquitoes. In the tropics, the 

 chief reservoirs of the malarial parasites are the native children, hence 

 European quarters should be away from native dwellings as far as 

 possible. Mosquito nets, having twenty to twenty-four meshes per 

 square inch, should be used invariably, and houses should be screened. 

 Malaria-conveying mosquitoes bite chiefly towards evening. Quinine 

 treatment for preventive purposes is important. A dose of 5 gr. of 

 quinine daily, with a dose of 10 gr. on the seventh day (Castellani), is 

 efficacious. Some workers, however, recommend a large close (15 gr.) 

 on two consecutive days every eight or ten days for three months, 

 while others recommend 10 gr. twice a week. Celli administered 3 gr. 

 of quinine morning and evening. 



The second line of attack is directed against mosquitoes, especially 

 Anophelines, on the lines so well set forth by Sir Ronald Ross. 1 The 

 accumulation of small quantities of water in various vessels, many of 

 them unnecessary, should be prevented, as Stegomyia (Culicines) breed 

 in such receptacles. Anophelines breed in small pools. All drinking 

 water and household vessels, water-butts and cisterns must be 

 effectively screened with wire gauze. Cesspools, etc., must also be 

 screened, and they, and all collections of water, should be oiled with 

 crude petroleum sprays every week or ten days, or fortnight according 

 to some workers. The petroleum is a good larvicide and suffocates 

 the Anophelihe larvae, while its presence renders the site obnoxious 

 to the adult mosquitoes. The amount of crude petroleum or kerosene 

 will vary according to the locality concerned, due regard being paid 

 to its powers of spreading on the surface treated. Different authorities 

 have used different quantities, such as i oz. of oil to i square yard 

 or to 15 square feet. Others have used i pint of the petroleum to 

 a circle of 20 feet in diameter, while ^ pint for every 100 square feet 

 of surface has also been recommended. The larvicide used so 

 successfully in Panama consisted of : 



Average mixture 



Crude carbolic acid (containing 15 per cent, phenol) ... 300 gallons 

 Caustic soda ... ... ... ... ... 30 Ib. 



Resin ... ... ... ... ... ... 200 Ib. 



One part of this mixture in 5,000 parts of water containing 

 mosquito larvae destroys them within five minutes ; i part in 8,000 

 of water kills larvae in thirty minutes. Small fish, such as the 

 " millions" fish, that feed on the larvae, can be introduced into 

 collections of water and are of local service. Ducks may also act as 

 destroyers of larvae. The growth of water-weeds and rank vegetation, 

 that affords shelter to the larvae, must be prevented as far as possible. 



Wherever possible hollows should be filled up, swamps and roads 



1 " The Preven'icn of Malar'a." Second Er iticn (191 1). London : John Murray. 



