MALARIAL PARASITE. 657 



A further step in the sexual process may be seen 

 in drop preparations of the blood, although this 

 step does not occur in the human body. From ten 

 to twenty minutes after such a preparation has 

 been made the male cells, after a period of agi- 

 tation, discharge from four to eight long, thin 

 flagella (microgametes or spermatozoa), which 

 thrash about violently and eventually come in con- 

 tact with a female cell, which they enter and be- 

 come unrecognizable. 



This same process is instituted and completed JJJj ^ito Uc 

 (sporogony) in the stomach of the mosquito, the 

 penetration of the female cell by the spermatozoon 

 resulting in the impregnation of the former. Fol- 

 lowing impregnation, the female cell gradually 

 assumes a worm-like or sickle shape (ookinet), 

 penetrates the wall of the stomach and becomes 

 encapsulated (oocyst). Forty-eight hours after 

 the mosquito has sucked malarial blood all the 

 female cells have reached this stage and no more 

 free parasites are found in the stomach. 



About five days after the blood was taken the Formation of 



, , J T . .. , Sporozoites. 



oocyst has increased in size about six times and 

 has formed within itself a number of small 

 spheres, which are called daughter cysts or sporo- 

 blasts. The latter soon acquire a finely striated ap- 

 pearance, which is due to the formation of hun- 

 dreds of "germinal rods" or sickles-like bodies 

 ( sporozoites). The latter are nothing less than 

 young malarial parasites, which are thrown into 

 the body cavity by the rupture of the oocyst, and 

 are carried to the salivary glands of the mosquito 

 by the lymphatic circulation. If the mosquito has 

 been kept at a temperature of 24 to 30 C. these 

 sickle forms first appear in the salivary gland after 



