78 DISEASES DUE TO PROTOZOA 



of the male cell break up, one filament bulls and bores its way into 

 the granular or female sex cell. Where this iilament or microgamete 

 disappears inlo the female cell a small minute papilla is thrown out to 

 meet the oncoming microgamete. No second filament can enter, no 

 matter how energetical Iv it attacks the impregnated cell. Later this cell 

 becomes oval, elongated lanceolate, and finally a vermicular form, the 



a h c d e 



Stages of development of peinicious or malignant terlian pirasi'es in the intestine of 

 Anopheles maadipennis. (After Grassi.) a, macrogametocyte (crcsceni) still attached to human 

 blood ci'fpuscles; b, macrogametocyte (sphere) half an hour after ingestion by ihe musquiio ; 

 c, microgametoc>te (crescent) attached to the blood corpuscle ; d, microgametocyte (sphere) 

 half an hour after ingestion ; the nucleus has divided several times ; e, micrugametes attached to 

 the residual body (polymitus stage). 



anterior end becomes pointed and hyaline, the posterior end broad 

 and granular as a result of the presence of the hiemozoin. The 

 vermiculc then moves about, and is now called the Ookinet. This can 

 pass through a red or white cell. The ookinet now passes through 

 the wall of the mosquito's stomach and the delicate basement mem- 

 brane of the stomach wall, and lodges amongst the longitudinal and 





i:^* 



^m-| 



Ookinete of the malignant tertian parasite in the stnmsich of ^/top/ie/es macu/ipe/i>ir's, thuiyAwo 



hours after ingestion of blood. (After Grassi.) 



transverse muscle fibres between the inner membrane and the outer- 

 coat of the stomach wall. Here it grows for a few days, becomes 

 spherical, accjuires a capsule, and by its increasing size bulges inwards 

 the stomach wall, it is now an Oocyst. Spherical daughter cells are 

 formed within it. Around these numerous spindle-shaped nucleated 

 bodies are formed, giving it the appearance of an apple studded with 

 needles. The spherules disappear and the spindles remain loose in 

 the capsule, and are now known as sporosoites. In about one week 

 ihe capsule ruptures and discharges its contents into the body cavity 



