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 (y), 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 Ehrenberg 
itwasconstitutedadistinctgenus, under the nameof Acineta. 
According to Dr Stein, who first made known the true 
nature and relations of these forms, the Acineta;. “have no 
mouth ; 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 
