ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



If we follow out the fate of the microspheric individual (Fig, 8, 7) we 

 find that it reproduces by a process of multiple fission or schizogony 



/ 



chn 



Fig. 8. 



Life-history of Polystomella according to Lister, i, Megalospheric individual ; aa and 26, gametes 

 derived from two different megalospheric individuals ; 3 and 4, syngamy ; 5, zygote (central proto- 

 plasm of new microspheric individual) ; 6, early stage in growth of microspheric individual ; 7, micro- 

 spheric individual ; 8 and 9, young megalospheric individuals derived from 7. b. Protoplasmic 

 bridge ; chf, chromidia ; M, central protoplasm of megalospheric individual ; m, central protoplasm 

 of microspheric individual ; n, nucleus ; P, peg-like projections of cytoplasm. 



