498 THE BEGINNINGS OF LIFE. 



Plossconia may fairly be supposed to have emerged from 

 the empty cysts l . 



And again, the same independent reasons which tend 

 to countenance the observations of M. Pineau also lend 

 support to those of M. Haime and Mr. Carter. Not 

 only may apparently similar vegetal vesicles be trans- 

 formed now into Vorticellas and now into Oxytrichse, 

 but, as we have seen (p. 468), others of them may be 

 converted into the characteristic form of Plaesconia. 



Other cases of such transformations will doubtless soon 

 be made out by subsequent observers, and in addition, the 

 altogether artificial distinctions now supposed to exist 

 between many of the forms of Ciliated Infusoria are 

 likely to disappear as our knowledge increases con- 

 cerning their more habitual developmental phases. 

 Systematic writers have long suspected that certain 

 ' species/ usually described as belonging to distinct 

 genera, are really only transitional states of other 

 forms, which may pass into one another quite gradually 

 without an intervening stage of encystment. A trans- 

 formation of Vorticellas into Oxytrichae without previous 

 encystment, has been described by Mr. T. C. Hildgard * ; 

 whilst I have also seen Paramecia derived from the 

 pellicle gradually assume the characters of Nassulse 3 . 



1 There was all the less chance of a mixture of the two Infusoria 

 having taken place originally, because the vessel, in which thousands 

 of the Keron<2 existed and from which the encysted specimens were 

 taken, did not appear to contain a single specimen of Plcesconia Charon. 



2 ' Monthly Microsc. Journ.,' Nov. 1871, p. 233, 

 s See p. 250. 



