VORTICELLA. 121 



seen within the stalk : this motion carries the 

 body instantaneously to a considerable distance ; 

 after a short time it uncoils again, and the ani- 

 malcule renews its occupation. This stalk, which 

 is about five times longer than its body, is a 

 marvellous structure : the muscle within, at the 

 will of the animal, can contract into many coils, so 

 suddenly that the eye cannot follow the motion, 

 though the effect is seen by the removal of the 

 body to a distance ; the uncoiling is not so 

 sudden, and much more graceful. Vorticella 

 group themselves together in hundreds, when 

 the scene is very animated, first one and then 

 another contracting ; and often the whole party 

 recede at once, as if animated by the same will, 

 then they expand again, and the same scene is 



M 



