130 THE MAIN CURRENTS OF ZOOLOGY 



different species. If they mature and produce spores 

 in thirty-six hours, the patient has chills and fever 

 every other day for the chills and fever correspond 

 to the period of sporulation and bursting of the 

 corpuscles. There are other species with a different 

 period of growth giving rise to the different types of 

 malaria the three-day, the four-day, etc. Minute 

 as they are these different varieties can be distin- 

 guished under the microscope. 



The question of how the parasite gets into the 

 blood had now to be solved as a step in tracing the 

 infection to its source. Suspicion was fastened on 

 the mosquito and after observations by several in- 

 vestigators it was finally shown in 1898 that the bite 

 of a particular species of spot-winged mosquito 

 transmits Malaria. (Grassi had previously shown 

 that these parasites complete a part of their life 

 history in the body of the mosquito.) The scientific 

 name of the mosquito is Anopheles. The Culex or 

 common house mosquito is not a malaria carrier. 

 The Anopheles is widely distributed. It is a night- 

 flier, and only the female circulates, sucks blood, and, 

 when infected, transmits the disease. 



In the most infected districts it was experimen- 

 tally demonstrated that to remain in well-screened 



