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ADVANCED PHYSIOLOGY 



a female mosquito bites a patient suffering from malaria 

 it will suck some of the red corpuscles containing the parasites 

 into its body. In the mosquito these parasites go through 

 some changes and finally come to lodge near its mouth. If 

 this mosquito later bites another person, the tiny parasites 

 are likely to be inoculated into the body where the skin is 

 pierced. Thus a second person is infected. This is the only 

 method by which malaria is known to be distributed. Hence 

 any means of getting rid of mosquitoes is a protection against 

 malaria. Mosquito netting at windows and doors is a very 

 efficient protection from this disease. Draining puddles and 

 pools and emptying all barrels of standing water where mos- 

 quitoes breed is another. Only one kind of mosquito dis- 

 tributes the disease and fortunately this 

 is not the most common kind. A method 

 of distinguishing it from the harmless species 

 is explained in Figures 71 and 72. 



Yellow Fever. Yellow fever is fortunately 

 uncommon in this country, occurring only 

 at rare intervals in the southern states. In 

 tropical countries, e.g. South America and 

 the West Indies, it is of more frequent 

 occurrence. Occasionally it does get into 

 our southern cities in the summer, and 

 in past years it has produced very serious 

 epidemics with thousands of deaths. Its 

 cause has recently been discovered to be 

 an extremely minute unicellular organism. It 

 is mentioned here because, like malaria, it is 

 known to be distributed by mosquitoes, though the species 

 carrying yellow fever germs, Stegomyia, is not the same as the 

 one which spreads malaria. 



These facts show clearly that mosquitoes are among our 

 most deadly enemies. The different states of the Union are 

 showing appreciation of this fact by appropriating con- 



FIG. 72. MOS- 

 QUITOES 



g, Anopheles, h, 

 Culex, as they 

 alight on the walls 

 of a room. 



