MALARIA AND ITS TRANSMISSION 13 



body with extracted blood. Manifestly, then, malaria 

 cannot exist in water, nor in air, nor in overripe fruit, 

 or the like. 



Water used for drinking purposes that was suspected 

 of being responsible for malaria in a given district was 

 used continuously in two communities (Penryn and 

 Oroville, California) during their anti-mosquito cru- 

 sades while malaria was on a steady decrease. The 

 sanitary inspectors drank this water, ate freely of 

 the ripest fruit during this time, exposed themselves 

 to the severest heat of the day, and yet remained free 

 from malaria, exercising, of course, the proper night 

 precautions. 



It is well known that malarial blood taken directly 

 from a patient suffering from malaria shows flagellated 

 parasites. Ross, in 1895, in his observations in India 

 found these flagellated bodies in the intestine of mos- 

 quitoes which had fed on the blood of malarial patients. 

 Many experiments were made and hundreds of mos- 

 quitoes examined during the next few years by Ross. 

 The most striking condition found in some of these 

 mosquitoes was the development of pigmented cells 

 in the stomach wall, the pigment corresponding to 

 malaria pigment. Some of this number gave positive 

 results, while the majority gave negative results. Those 

 that furnished the positive results were of a particular 

 species, and this gave the clue that the malaria parasite 

 required a particular species of mosquito to serve as 

 intermediary host. The connection between the flagel- 



