INSECTS IN RELATION TO OTHER ANIMALS 303 



himself to be bitten by the insects. Though previously free 

 from the malarial organism, he contracted a well-marked 

 infection as the result of the inoculation. 



Furthermore, it is highly probable that malaria cannot be 

 transmitted to man except through the agency of the mos- 

 quito. This appears from the oft-cited experiment of Doc- 

 tors Sambon and Low on the Roman Campagna, a place 

 notorious for malaria. There the experimenters lived during 

 the malarial season of 1900, freely exposed to the emanations 

 of the marsh and taking no precautions except to screen 

 their house carefully against mosquitoes and to retire indoors 

 before the insects appeared in the evening. Simply by ex- 

 cluding Anopheles mosquitoes, with which the Campagna 

 swarmed, these "investigators remained perfectly immune from 

 the malaria which was ravaging the vicinity. 



In a later experiment on the island of Formosa, one com- 

 pany of Japanese soldiers was protected from mosquitoes and 

 suffered no malaria, while a second and unprotected company 

 contracted the disease. 



The evident preventive measures to be taken against ma- 

 laria are ( i ) the avoidance of mosquito bites, by means of 

 screens, and washes of eucalyptus oil, camphor, oil of penny- 

 royal, oil of tar, etc., applied to exposed parts of the body; 

 (2) the isolation of malarial patients from mosquitoes, in 

 order to prevent infection; (3) the destruction of mosquitoes 

 in their breeding places, especially by the use of kerosene and 

 by drainage. During unavoidable exposure in malarious 

 regions, quinine should be taken in doses of six to ten grains 

 during the day at intervals of four or five days (Sternberg). 



Culex and Anopheles. The mosquitoes of North America 

 number one hundred and twenty-five known species. Of these 

 only the genus Anopheles transmits malaria to man, though in 

 India, Ross found that Culex transmits a form of malaria to 

 sparrows. These two common genera are easily distinguish- 

 able. In Culex the wings are clear; in Anopheles they are 

 spotted with brown. In Culex when resting, the axis of the 



