XCVl 



THE BEGINNINGS OF II FE. 



/ 



* 'Journ, of Microsc. Science/ 185 7' P* 96' 



;.t Stein"'" 



*"' ssess th 



she 



or 



two 



r 



Withi 



II 



more rows of cilia, by means of which, before effecting its 

 exit, it moves about in the cavity in which it is contained. 

 Its body is made up of a finely-granulated sarcode, contain- 

 ing a band-like nucleus in its posterior portion, and closely 

 adjacent to this there is a distinct contracting vesicle. ' No 

 mouth is visible, but on the whole it presents a form which 

 would seem easily convertible into a Vorticella ; and this 

 Stein beUeves to be its next developmental stage. 



A more or less similar life-history is, he believes, the rule 

 with very many of the Ciliated Infusoria. Cienkowski, 

 Kolliker and others, however, believe that Stein has con- 

 founded certain Acznetce with members of the family Adino- 

 phryna^ and although they fully admit that AcinetcE do de- 

 velop ciHated embryos in their interior similar to those 



r 



described by Stein, Cienkow^ski and some others believe -usual solitary 

 that such ciliated embryos are reconverted into Acineta-XxkQ i-ielopment seen 



with a 

 ,« six oval, ( 

 #ed to have 

 3ti of the Acin 



])- 



t 



contained a c 

 In one 

 to the pre! 



organisms, and that they do not give rise to Vorticellce as . ;tlie reproductiv 



alleged by Stein. Cienkowski's observations^ on one occa- Wk^ at the 



sion were undoubtedly sufficiently positive to entitle him to 



come to the conclusion that ' from the Acineia-QvahxyOy after 



a prolonged motile stage, another Acineia is formed, but, as 



he himself admits, his ' observations do not, of course, show 



that it is impossible that the motile ^^iiWa-embryo should 



be transformed into a Vorticella^ and a Vorticella-cy^i into 



an Acineia.'^ 



Cienkowski's observations would only really militate 

 against those of Stein, if we were to assume, what is highly 

 improbable, viz., that the developmental metamorphoses 

 amongst this group of animals are in all cases the same. 

 Much evidence exists, pointing to the conclusion that 

 there is the greatest variabiUty on different occasions, and, 

 consequently under the influence of different sets of con- 



'4i I qg 



.sn described ar 

 ■^reader bj the 

 "^ to the con( 

 ;¥o(luction f( 



-) different d 



reproduc 

 ^^ ^^' Partici 

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^^tual pr, 

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