220 PROTOZOAN PARASITISM 



and division is repeated. This is the ordinary process 

 taking place entirely within the parasite's habitat in 

 the single host. 



Periodically in the life of the parasite, supposedly 

 as a rejuvenation process inherent in the organism, 

 but due to unknown influences, the Merozoites, af- 

 ter penetrating epithelial cells, instead of maturing 

 into asexual Schizonts, develop into male organ- 

 isms, called Microgametocytes (7 and 8), and females 

 (11), called Macrogametocytes. In the males the 

 organism grows, at the expense of the host cell, the 

 nucleus multiplies (9) and the body of the male 

 splits off a number of flagellated individuals (10) 

 corresponding to the number of multiplied nuclei. 

 These bodies, called Microgametes, burst the confines 

 of the host cell, leaving the remnant of it and the 

 parent Microgametocyte and swim actively about 

 until they come in contact with the female cell, cor- 

 responding to spermatozoa and their means of mak- 

 ing contract with the ovum. 



The young female (]\Iacrogametocyte) after en- 

 tering an epithelial cell does not multiply in a com- 

 parable fashion but enlarges and matures, at the 

 expense of the cell host, into a single cell, called the 

 Macrogamete (12, 13), thus corresponding to the 

 ovum of the multicellular animal. The mature fe- 

 male element, the Macrogamete, is found by the male 

 element, the Microgamete, within the remnant of 

 the used up host cell ( 14) . When the free swimming 

 spermatozoon-like Microgamete, which is produced 



