134 GENERAL BIOLOGY 



ence are always performing, and (3) it will show him what great quan- 

 tities of material must be sifted before one can prove an accepted scien- 

 tific theory, or advance a new one. 



It was on November 6, 1880, that Dr. Laveran, a French army 

 surgeon serving in Algeria, plainly saw the living parasites under the 

 microscope in the blood of a malarial patient. But it was not until five 

 years later that medical men accepted his findings. Then several 

 Italian pathologists, prominent among them being Golgi, Marchiafava, 

 and Celli, worked out the behavior of the parasite in human blood. 

 These men found that the fever and chills always came at definite 

 periods of development in the parasite. 



But they could not find how the parasite got into the blood of the 

 patient. The name "Malaria" is Italian and means "bad-air'.' (malaria) 

 and the disease had always been associated with swamps and stagnant 

 water, so it is not strange that mosquitos had been thought of as hav- 

 ing some relationship to the disease. Medical men were, however, 

 inclined to consider such a thought as savoring too much of superstition 

 to consider it. 



Notwithstanding this general attitude, Dr. A. F. A. King, an Amer- 

 ican physician, in 1883 summed up the evidence which to him seemed 

 quite conclusive for such an association. 



Riley and Johannsen have put Dr. King's argument in the follow- 

 ing words : 



1. Malaria, like mosquitoes, affects by preference low and moist 

 localities, such as swamps, fens, jungles, marshes, etc. 



2. Malaria is hardly ever developed at a lower temperature than 

 sixty degrees Fahr., and such a temperature is necessary for the devel- 

 opment of the mosquito. 



3. Mosquitoes, like malaria, may both accumulate in and be ob- 

 structed by forests lying in the course of winds blowing from malarious 

 localities. 



4. By atmospheric currents malaria and mosquitoes are alike capa- 

 ble of being transported for considerable distances. 



5. Malaria may be developed in previously healthy places by turn- 

 ing up the soil, as in making excavations for the foundation of houses, 

 tracks for railroads, and beds for canals, because these operations afford 

 breeding places for mosquitoes. 



6. In proportion as countries, previously malarious, are cleaned up 

 and thickly settled, periodical fevers disappear, because swamps and 

 pools are drained so that the mosquito cannot readily find a place suit- 

 able to deposit her eggs. 



7. Malaria is most dangerous when the sun is down and the dan- 

 ger of exposure after sunset is greatly increased by the person exposed 

 sleeping in the night air. Both facts are readily explicable by the mos- 

 quito malaria theory. 



