IX] OBLITERATION OF BREEDING PLACES I49 



Preventive action therefore aims at bringing about more 

 or less perfectly one or more of these conditions. Theoretically 

 any one of the three, if completely reahzed, would suffice to 

 prevent any fresh transmission of malaria, and finally to ex- 

 terminate the disease. Unfortunately in practice it is usually 

 possible only ^'ery imperfectly to achieve the desired end in any 

 of these directions, and it becomes necessary to combine the 

 effects of as many methods as possible. Circumstances alone 

 can determine in any given case which line of action is most 

 called for, or what combination of methods is likely to be most 

 effective. 



Under the first head come all measures which have as their 

 object the reduction in the number of Anophelines present. 

 Such action may be direct, as in the case of anti-mosquito 

 campaigns, or indirect as by the extension of agriculture, or 

 large drainage measures. Under the second head come various 

 methods of quinine prophylaxis, ah agreeing in the use of 

 quinine as a destroyer of the parasite in the human host, but 

 differing a good deal in the immediate object arrived at. Under 

 this head also come certain measures applicable to mixed 

 communities as the " Removal or prophylactic treatment of 

 the reservoir of infection," " Segregation of the healthy," and 

 the avoidance by the individual of sources of infection generaUy. 

 Under the head of protection are included such measures as 

 the screening of dwellings and barracks, the use of suitable 

 protective clothing, and the use of the mosquito net. 



I. Many methods of attacking Anopheles are now known, 

 the more important being : 



The obliteration of breeding places. By minor drainage 

 measures, filhng up pools or depressions with earth and, in 

 some cases, subsoil drainage, pools utilized by Anopheles for 

 breeding may be completely done away with. In cases where 

 it is difficult or impossible to carry out such action, breeding 

 places may be made less suitable by clearing out weeds, deepen- 

 ing, and perhaps even hning with masonry, the edges of large 

 sheets of water. Not infrequently the chief sources of Anopheles 

 are to be found in connection with small streams, in which case 

 training in some form or another should be performed. Where 



