THE CONSERVATION OF LIFE 



235 



patient. Later, by the co-operation of English, Italian, German, 

 and French investigators, its relation to malaria and its strange 

 life-history were clearly ascertained. 



These species of malaria parasite are distinguished : Plasmo- 

 dium (Hamamceba) prcecox, vivax, and malarice. Whether these 

 three forms are really three separate species, or only varieties 

 of the same species appears doubtful, especially as all three 



10 



PIG. 57. LIFE-CYCLE OF THE MALARIA PARASITE OF MAN. 



(1-5) Stages of development in the human blood. (6-11) Stages of development 

 in the Anopheles. (1) Sporozoites. (2) Sporozoite has invaded a red blood-corpuscle. 

 (3) Sporozoite becomes a monont. (4) Nucleus multiplication. (5) Spore forma- 

 tion. (6) Female germ (oogony). (6") Male germ (antheridium). (7) Mature 

 female germ. (7') Formation of microgametes. (8) Fertilization. (9) Fertilized 

 oogony (amphiont). (11) Development of gymnospores in the interior of the 

 amphiont. 



are dependent upon the same hosts, man and a mosquito 

 (Anopheles). These three parasites are the cause of the three kinds 

 of human malaria which are distinguished as perniciosa, tertiana, 

 and quartana. I shall deal here with the cause of tertiana, 

 Plasmodium vivax. The other two closely conform in their mode 

 of life to this .species. 



If we examine the blood of a fever patient we find in the 



