INFUSORIA. 



15 



the surrounding water, and imparting a tremulous motion 

 to the whole bell. 



It is evident now that the separation is imminent, for 

 the minute point of connexion cannot long withstand the 

 rushing current of these rotatory paddles. At length the 

 bell suddenly shoots away (g), gliding with great swiftness 

 through the water, borne by its numerous paddles, and 

 whirls about for a while in a headlong, giddy manner. 

 At length it chooses a place of rest, becomes stationary, 

 fixes itself by that end which had formerly been the 

 mouth, but is now closed up, and presently begins to rise 

 by the development of a slender stalk, which, though 

 minute at first, quickly increases in length, until it attains 

 the original dimensions. 



But another mode of increase, yet more singular, has 

 been found to prevail in these creatures. At certain 

 periods the Vorticella closes its ciliated mouth, and passes 

 into a sort of chrysalis state, taking a globular or bladder- 

 like form, with a distinct double wall. After remaining a 

 while m this encysted condition, pencils of slender fibres 

 shoot out from two or more points, each fibre terminated 

 by a minute globule. This form has been often detected 

 by the older observers, without a suspicion that it was but 

 a stage in the metamorphoses of Vorticella. By Ehreuberg 

 it was constituted a distinct genus, underthe nameof Acineta. 



According to Dr Stein, who first made known the true 

 nature and relations of these forms, the Acinetce " have no 

 mouth j it is, indeed, difficult, from the toughness of their 

 tunic, to effect a rupture ; no food or stomach sacs, like- 

 wise, can be found in them, their substance being homo- 

 geneous, granular, soft, and containing, besides its very 



