ANTI-MALARIAL MEASURES 103 



the natives, and especially prevention of the access of 

 infected native children into European households. 



Since Ross's famous discovery of the part played 

 by the mosquito in the spread of malaria, many 

 attempts have been made at mosquito destruction. 

 The weak point in the life-history of the mosquito 

 or gnat alike is the larval period. Attempts at 

 destroying the larvae depend on either the permanent 

 destruction of the insects' breeding-places, or on 

 rendering these places unavailable or too objection- 

 able to permit of either larval life or of egg-laying. 

 Experiments have been made in India, British 

 Guiana,* America, and Africa, by draining the land 

 where possible, and by keeping aqueducts and canals 

 free from floating debris that affords shelter to the 

 larvae, and thus reducing the numbers of adult 

 insects. These have been partially successful. 



In Africa such measures are not so successful as 

 in India. Native villages are near water, and it has 

 been found that the chief haunt of the mosquito in 

 Africa is the native huts. Drainage on the scale 

 necessary for efficient protection from mosquitoes 

 would be most costly, though the use of modern 

 apparatus, such as sand-pumps for filling swamps, 

 has greatly reduced the cost. But much can be 

 done in any malarial district to reduce the number 

 of mosquitoes by preventing the access of the adults 

 to the numerous unnecessary receptacles that are 

 capable of containing water, and so becoming 

 breeding-places. Old tins, broken crockery, un- 

 necessary water- jars all should be removed. 

 * See Frontispiece. 



