CONJUGATION OF VORTICELLA. 175 



; nucleus. These are finally liberated by the bursting of the 

 membrane, acquire a ciliated belt, and after swimming for a 

 -time become attached, lose the ciliated belt, and develop^ stalk 

 and peristome. 



Vorticella goes through a process of conjugation which has 

 some interesting peculiarities. (1) Conjugation always takes 

 place between a large attached individual (the macrogamete) and 

 a much smaller free-swimming individual (the microgamete} 



FIG. 91. Fission and conjugation of Vorttetlla. A. Early stage of fission, showing- 

 division of micronucleus (mic) and macronucleus (mac) ; p, peristome. (After 

 Blitschli. ) 



.B, C, D. Successive stages of fission ; in B and C the nuclei have completely di- 

 vided and fission of the cell-body is in progress; r.r, contractile vacuoles. In 

 D fission is complete; the right-hand individual has acquired a belt of loco- 

 motor cilia at x, and is ready to swim away. 



E. Conjugation of a fixed macrogamete (ma) with a free-swimming microgamete 

 (ml) ; p, peristome, ep, epistome. (After Green 5 .) 



(Fig. 91 , E]. The microgamete is formed either by the unequal 

 fission of an ordinary individual, the smaller moiety being set 

 free, or by two or more rapidly succeeding fissions of an ordinary 

 individual. (2) Conjugation is permanent and complete, the 

 body of the microgamete being wholly absorbed into that of the 



