52 3I0SQUIT0ES 



are active and penetrate rapidly into the tissue of the 

 salivary duct and so into the proboscis of the mosquito, 

 and, with the saliva or poison, they enter the blood of the 

 next warm-blooded animal which the moscpiito l)ites. It 

 is then supposed that the blasts enter the red blood cor- 

 puscles and the development re-begins at the stage where 

 we took it up. 



It is thus shown that the full development of the mala- 

 rial parasite cannot take place within the human body ; 

 that the Anopheles mosquitoes are necessary secondary 

 hosts ; that the sexual generation of the parasite takes 

 place only in mosquitoes of the genus Anopheles ; and 

 further, that the old ideas of malaria from bad air (and of 

 course the word mcdaria means bad air), swamp " miasma," 

 and so on, are to the minds of those familiar with the 

 subject of the biology of these low forms of life com- 

 pletely overturned. 



Reasoning from the life history of the parasite alone, as 

 observed, would not, however, satisfy the minds of jieople 

 at large, and, in fact, it did not satisfy many medical men 

 who were not especially familiar with this field of bio- 

 logical research. Very many practical demonstrations 

 have therefore been made. One of the most interesting 

 was that carried on by Professor Grassi, the Italian, 

 during the summer of 1900, in the Plain of Cappacio, near 

 Salerno. The objects of this experiment were : (1) To 

 afford an absolute proof of the fact that malaria is trans- 

 mitted exclusively by the bite of Anopheles mosquitoes ; 

 (2) To found, on the results of recent research, a code 

 of rules to be adopted for freeing Italy from malaria 



