The Protozoa 135 



quantities of material must be sifted before one can prove an accepted 

 scientific 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). 

 As the disease had always been associated with swamps and stagnant 

 water, it is not strange that mosquitoes had been thought of as having 

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

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

 accept 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 following 

 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 develop- 

 ment 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 

 capable of being transported for considerable distances. 



"5. Malaria may be developed in previously healthy places by 

 turning 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 suitable 

 to deposit her eggs. 



"7. Malaria is most dangerous when the sun is down and the 

 danger of exposure after sunset is greatly increased by the person 

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

 the mosquito malaria theory. 



"8. In malarial districts the use of fire, both indoors and to those 



