ro 



iNFrsoraA. 



is sometimes followed by a remarkable snccession 

 of phenomena, which have been thus described 

 by their discoverer, as they occur in the case of 

 Vorticella 'microstoma {fig. 15). An old Vor- 

 ticella loses or retracts its cilia, becomes encysted 

 {a) and finally drops off its stalk (6). The 

 cyst may either burst and discharge its contents 



Fig. 15. 



Development of Vokticei.la microstoma : — a, old Vorti- 

 cella in its encysted state, the nncleus and contractile vesicle 

 being visible within the body ; b, the same, detached from its 

 stalk ; c, cyst discharging its contents ; d, the band-like nucleus, 

 isolated ; e, Acineta form of encysted Vorticella ; f, stalked Aci- 

 neta (^ = Podophyra) form of the same ; g, two Acineta forms in 

 a state of conjugation j h, two Podophyra forms in the same con- 

 dition. 



in the manner already indicated (c), or become 

 changed into an '^ Acineta form " {e). The latter 

 may subsequently develop a stalk, so as to as- 

 sume the appearance of a " Fodophyra " (/ ). In 

 either instance, the band-like nucleus becomes 

 transformed into a peculiar ovate body, the narrow 

 end of which is provided with a circlet of vibratile 

 cilia, whilst a mouth leading into an internal 



