SPOROZOA 



423 



cyst and within this an enormous number of very slender sporozoits 

 are developed. The ripe cyst bursts into the body cavity and the- 

 sporozoits become generally distributed throughout the body of 

 the insect and later assemble in the secreting cells of the salivary 

 glands, from which they escape into the human host when the 

 mosquito bites. The cycle in Anopheles requires eight days at a 

 temperature of 28 to 30 C. At temperatures below iyC. the 

 microgametes are not produced. 



Development of the estivo-autumnal parasite through the 



\ 



FIG. 197. Section through salivary gland of Anopheles showing numerous 

 sporozoits of Plasmodium falciparum. i, Fat bodies; 2, gland duct; 3, sporozoits of 

 Plasmodium; 4, Secretion in the gland cells. (From Doflein after Grassi.} 



stages of schizogony has been obtained by Bass and Johns 1 in the 

 test-tube, in a medium consisting of defibrinated blood to which 

 0.5 per cent glucose has been added. They were able to keep the 

 organisms alive for ten days at a temperature of 40 C., during 

 which period the developmental cycle was repeated four or five 

 times. Their findings have been confirmed by other investi- 

 gators. More recently Joukoff 2 has reported partial development 

 in the test-tube, of the cycle of sporogony in the case of PL falci- 



1 Journ. Exp. Med., 1912, Vol. XVI, pp. 567-579. 



2 Compt. Rend. Soc. BioL, 1913, Vol. LXXIV, pp.Ji36-i38. 



