38 



iMFJac.l.X MUSEUM GUIDE LEAFLETS 



"tropical" malaria, the mild local form of which is known as "sestivo- 

 autumnal." The intervals which separate the paroxysms correspond in 

 length to the duration of the process of spore-formation in the blood 

 cells, the chills marking the liberation of the spores (sporulation). The 

 parasites which produce the three different forms of malaria are consid- 

 ered to he separate species, distinguished chiefly by a difference in the 

 time required for the completion of their cycle of development in the 

 human blood. In this connection it is of interest that immunity against 



OOKINETES ENTERING THE STOMACH WALL 



OOKINETES WITHIN THE CELLS OF THE STOMACH 



FIG 30. STOMACH OF THE MALARIA MOSQUITO 



Ookinetes are shown entering the stomach wall. Diagrammatic. .Magni- 

 fication about 30'diameters. 



CYSTS CONTAINING MALARIAL SPORES 



FIG 3 1 STOMACH OF THE MALARIA MOSQUITO 

 Malarial "Sporocysts" are shown on the outer wall of the organ. Longi- 

 tudinal section diagrammatic. Cross section after Grassi. Magnification about 

 25 diameters. 



one form of malarial organism has been found by Professor Koch not to 

 insure immunity against the other two species. The parasite of the 

 tropical variety differs from the others in respect to the appearance of 

 the >e\ual forms, which are half-moon or crescent-shaped. It was these 

 which were first found by Laveran, and they are termed the "half- 

 moons of Laveran." 



With the extermination of the mosquito of a malarial neighborhood 

 the disease will, in time, disappear. Xuttall on the other hand describes 

 districts in England from which malaria has disappeared, although the 



