30 
PROPHYLAXIS OF MALARIA. 
which occur in the blood of man and which are intended to complete 
their development in the mosquito. 
Morphology of the sexual forms of the plasmodia occurring in 
the blood of man .—The forms of the malaria plasmodia concerned 
in sporogony , or the mosquito cycle of development, which can be 
demonstrated in the blood of the human host are of the greatest 
importance in the prophylaxis of these infections, and their recog¬ 
nition essential in any scientific campaign against malaria. The 
Fig. 1. — Development of Plasmodium vivax within the mosquito. 1, Ookinete; 2, oocyst : 
3, 4, 5, oocysts showing the development of sporoblasts; 6 and 7, oocyst showing 
development of the sporozoites, which are fully formed in 7 ; 8, sporozoites within a 
cell of the salivary gland ; 9, sporozoites ; 10, entrance of sporozoite into a red blood 
corpuscle; 11, middle intestine (stomach) of mosquito, showing several oocysts in the 
wall of the organ. (Original.) 
presence of these sexual forms proves beyond question that the indi¬ 
viduals in whom they occur are infective to mosquitoes, and that they 
are thus true u carriers “ of malarial disease. The proper treatment 
of these “ carriers *' is thus dependent upon the differentiation of the 
sexual forms or gametes and no malaria survey can be considered 
complete unless the percentage of individuals showing gametes is 
ascertained and proper measures be taken to render them harmless. 
As already stated, the gametes are sexually differentiated, the male 
being called a microgametocyte and the female a macrogametocyte, 
