THE SPOROGONY OF THE MALARIAL PLASMODIA 97 



Numerous works then followed, mostly relating to the sporu- 

 lation of the plasmodium which takes place in the body of the 

 mosquito 1 (Ross, " The Proteosoma of Birds in Species of Culex " ; 

 Grassi, "The Plasmodia of Man in Species of Anopheles " ; Bignami 

 and Bastianelli (8), " The Tertian Parasites" ; also Koch and others). 

 Schaudinn(io) pointed out the analogy with the development of the 

 coccidia. 



Schizonts alone are found in the blood of malaria patients in 

 fresh infections. It is only after a certain time that, in addition, 

 the gametes (crescents, sickles, or spheres) appear in gradually 

 increasing numbers. The difference between male and female 

 individuals (microgametocytes and macrogametes) in the plasmodia 

 of human malaria is not so great as is the case in the proteo- 

 soma of birds or in the coccidia. 



a. b, c. d. 



FIG. 40. Stages of development of the pernicious parasites in the intestine of 

 Anopheles maculipennis (after Grassi). (a) Macrogamete (crescent) still clinging to the 

 human blood corpuscle ; (b) macrogamete (sphere) half an hour after the mosquito has 

 sucked ; (c) microgametocyte (crescent adhering to the blood corpuscle) ; (d) micro- 

 gametocyte (sphere) half an hour after sucking (the nucleus is broken up) ; (e) 

 microgamete attached to the residual body (polymitus stage). 



When conveyed into the intestine of Anopheles they mature 

 rapidly, and the filamentous microgametes, which are chiefly 

 composed of nuclear substance, but have no flagella, penetrate 

 into the macrogametes which, shortly before, have reduced their 

 nucleus. The copula thus formed is not immediately transformed 

 into an oocyst as is the case with the coccidia, but first becomes 

 a motile fusiform body (" vermicule," Danilewsky, " ookinet," 

 Schaudinn, fig. 41), which bores actively into the intestinal wall 

 of the mosquito's stomach, where it settles. A very delicate 

 integument, which is probably a product of the host, then develops 

 on the surface of the ookinet, which becomes round, and the 

 oocyst is thus formed. The number of parasites in one mosquito 

 may be very considerable. As they become gradually larger they 

 project like protuberances beyond the outer surface of the pos- 

 terior mid-gut, which is greatly dilated (fig. 42). 



1 For the classification, structure and life history of mosquitoes, see The Diptera. 

 7 



