JIALABIA AMj MOSi^UITOES 49 



iiioii crow, contributed i2;reatly to tlie elucidation of a 

 kjiotty point in the life liistoiy of the parasite ; the stud- 

 ies of Koss upon the malarial disease of sparrows in India 

 proved effectively the transmission of this disease by 

 mosquitoes ; while the exi^erimental demonstration of 

 the transfer of the parasite of human malaria by mosqui- 

 toes was first performed by Italian investigators, al- 

 thoug-h it has since been done many times in many parts 

 of the world by workers of many different nationalities. 



The life history of the malarial parasite of human kind 

 maybe briefly summarized as follows: All of the mahi- 

 rial parasites are protozoans, that is to say animals — and 

 not bacteria, that is to say plants. In the human blood 

 these protozoa inhabit the red blood cori)uscles and in 

 the blood they g-o through a sporulating- existence, which 

 may continue indefinitely unless checked by quinine or 

 in some other way. In the red corj)uscle the j)arasite 

 appears as an amosbula which g-radually grows until it 

 nearly fills the interior of the corpuscle, digesting- appar- 

 ently the red coloring matter of the blood and forming, as 

 the result of this digestion, pigment spots in its interior. 

 On reaching full growth the nucleus of the anujebula 

 suljdivides, each division gathering about itself a certain 

 amount of protoplasm, until instead of the single amoe- 

 bula the corpuscle contains a large number of spores. 

 The walls of the corpuscle then break, and the spores are 

 liberated into the blood serum. From a single infection 

 this sporulation or liberation of the spores takes place 

 [)ractically simultaneously and marks the beginning of 

 the malarial si)asm. 



