CONJUGATION OF VORTICELLA. 



175 



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

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

 time become attached, lose the ciliated belt, and develop a stalk 

 and peristome. 



Yorticella goes through a process of conjugation which lias 

 some interesting peculiarities. (1) Conjugation always takes 

 place between a large attached individual (the macrogamete) and 

 a much smaller free-swimming individual (the nvicrogainete) 



c.v 



mtc 



Fig. 91.— Fission and conjugation of VorticcWa. A. Early stage of fission, showing- 

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

 Biitschli. ) 

 B, C, -D. Successive stages of fission ; in J3 and C the nuclei have completely di- 

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

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

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

 JE. Conjugation of a fixed macrogamete {ma) with a free-swimming microgamete 

 {imX\\ p, peristome, cp, epistome. (After Greeflf.) 



(Fig. 91, K). The microgamete is formed either by the unequal 

 fission of an ordinary individual, the smaller moiety being set 

 free, or by tw'O 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 



