122 VIGNETTES FROM INVISIBLE LIFE. 



so, when the drawing-in process is commenced, 

 the tubular tentacle assumes a spiral form, which 

 allows of its being coiled up to a certain extent 

 and reversed on its again expanding. Thus they 

 are emptied of their contents into the body, and 

 kept always free for the suctorial process when- 

 ever opportunity occurs. 



In reverting to the very variable character of 

 the Acinetina, one is somewhat helped to a compre- 

 hension by contrasting it with the same character 

 in the Amoeba. In this latter we have a small bit 

 of jelly-like matter, which, Proteus-like, changes 

 its form continually while under your observation ; 

 but in the Acineta, though the several changes are 

 probably quite as great, yet each individual, how- 

 ever much it may be unlike its fellow, rigidly 

 preserves the one form it has originally acquired. 

 Thus the changes of form which in the one 

 case takes place in the individual, in the other 

 is spread over many. The form the individual 

 Acineton gets is fixed until some important func- 

 tion of its little destiny has to be accomplished. 



