92 SOME MINUTE ANIMAL PARASITES 



days' rest as a pupa, the full-grown insect emerges 

 from the pupa case, uses the latter structure as a stand 

 on which to dry its wings, and then flies off to seek 

 a mate and to begin its work of propagating its 

 species. Connected with this latter function of the 

 mosquito is the health or disease of man, for before 

 egg-laying can be accomplished, the female mosquito 

 needs blood to supply the necessary energy. 



Near by where the female emerged from the pupa 

 is a small native settlement, with children running 

 about. They seem healthy enough as they play, but 

 among them are many who now harbour malarial 

 parasites (Plasmodia) without being much incon- 

 venienced thereby. A quick swoop, a sharp stab, 

 and the mosquito begins to suck the infected blood 

 of the malarious child. Some of the parasites perish 

 almost as soon as swallowed, but others persist. 

 They are of two kinds (Fig. 21, B-D, c?, ?) Some 

 are the forms that produce the males (Fig. 21, B, c?); 

 others are destined to develop into the female forms 

 (Fig. 21, B, ?). The male progenitors (micro- 

 gametocytes) are somewhat smaller, have a large 

 nucleus and light-staining cytoplasm, while the 

 females (macrogametocytes) have a smaller nucleus 

 and a larger amount of darker-staining cytoplasm. 

 All other blood forms of the parasite, which are rather 

 numerous, perish in the stomach of the Anopheles. 



The male organism rounds itself off and its nucleus 

 divides rapidly into about four to six parts (Fig. 21, 

 C, 6*) which move out to the edge of the parent cell. 

 Suddenly, and with explosive violence, the nuclei 

 elongate, and threadlike bodies (microgametes), sug- 



