26 ESSENTIALS OF ZOOLOGY 



degenerates and finally disappears. When the trophozoite is 

 fully grown it contains granules of pigment. It becomes 

 rounded ; the nucleus splits up into a large number of nuclei, 

 which are liberated with a share of the cytoplasm. These 



Encystment of 

 gametocyte? 



Gametes 



Sporozoites in spores 

 (pseudonavicella) 



Seminal vesicle of earthworm with 

 cysts containing spores 



Cyst containing 

 spores 



FIG. 10. Monocystis. Diagrams illustrating life-history. 



invade other red corpuscles or are destroyed with the broken- 

 up corpuscles by the leucocytes of the blood. Such cycles are 

 repeated several times, and this phase of the life-history is 

 called that of schizogony. It is followed by a sexual change. 

 The fully grown Plasmodium becomes oval in shape and then 

 crescentic, and male and female crescents can be distinguished 

 by certain characters. 



