6i8 



Insects and Disease 



of the three well-known types of malarial fever, namely, quartan, tertian, 

 and remittent. And soon after 1885, Golgi and other investigators, Italian, 

 English, and American (Celli, Grassi, Mannaberg, Bignami, Danielewsky, 

 Carter, Osier, La.hh6, Koch, Manson, Councilman, Thayer, MacCallum, 

 and others), succeeded in working out in minute detail the behavior, develop- 

 ment, and pathological elTects, direct and indirect, of the parasites in the 

 human blood. From these researches I may summarize the life of the malaria- 

 producing Ha^mamccbjE in the human body as follows: The youngest para- 

 sites, or ama-bula.', are found living within the red blood -corpuscles; here 

 they grow at the expense of the corpuscle substance. They increase rapidly 

 in size, while the blood -corpuscle begins to degenerate. From the break- 

 ing down of the hiemoglobin of the corpuscle, due to the metabolism of the 



Fig. 798. — Diagrammatic figure of stages in the development of the malaria-producing 

 Ha;mamoeba (Plasmodium) in a red blood-corpuscle of the human body. 



parasite, granules of a blackish pigment are formed; this is the melanin 

 long known as a regular diagnostic characteristic of malaria. After a few 

 days, from one to several depending on the variety ot the Hsmamceba, the 

 amoebulae reach maturity. They begin now to sporulate; that is, the nucleus 

 and cytoplasm divide into many small parts, each nuclear part having aggre- 

 gated about it part of the cytoplasm. The walls of the blood-corpuscle then 

 break, and these many Hacmamceba spores are released into the blood-plasma. 

 Each of these spores soon attaches itself to a fresh blood-corpuscle, pene- 

 trates it, and begins a new life-cycle. It is obvious that such a parasitic life 



