54 



MANUAL OF ZOOLOGY 



SECT. 



individuals, with interchange of the substance of the micro- 

 nuclei, occurs in many of the ciliate Infusoria. In some 



E 2 



FIG. 22. Vorticella. A, B, living specimens in different positions ; C, optical 

 section ; D 1 , D-, diagrams illustrating coiling of stalk ; E 1 , .-, two stages in 

 binary fission ; E 3 , free zooid ', F*, F-, division into mega- and microzooids ; 

 G 1 , G-, conjugation ; H 1 , multiple fission of encysted form; H-'-H", develop- 

 ment of spores ; euc.f. axial fibre ; cort. cortex ; cti. cuticle ; c. vac. contractile 

 vacuole ; d. disc ; ^nll. gullet : m. microzooid ; vith. mouth ; nu. meganucleus ; 

 per. peristome. (From Parker's Biology, pactly after Saville Kent.) 



