COCCIDIUM. 



101 



freed in the gut the sporozoite progresses by forward gliding 

 movements, alternating these by flexions, bending itself like 

 a bow and straightening out again. When about to enter 

 an epithelial cell it presses the anterior end through the cell 

 wall and wriggles its way in. Once within the cell in which 

 development is to proceed, its movements gradually cease, 



FIG. 45. Life history of Coccidium. 



i. Sporozoite ; 2. Sporozoite entering and a trophozoite within an epithelial 

 cell ; 3-4. Schizont, forming merozoites ; 5. Merozoites entering another 

 cell ; 6 a . Merozoite forming macrogamete ; 6 b . Meorzoite forming 

 microgametes ; 7. Free microgamete ; 8-9. Fertilisation of macrogamete 

 by microgamete; 10. Zygote within oocyst ; n. Formation of spores 

 within oocyst ; 12. Spores forming sporozoite^. 



but it may pass through several cells before coming to rest. 

 Within the host cell the coccidium now in the trophozoite 

 stage becomes oval in form, and in about twenty-four hours 

 has reached full size and has exhausted the host cell 

 contents. This is the completion of the trophozoite period, 



