148 



DROPS OF WATER. 



near the base of the rotators ; so that its 

 border becomes inflected when the animal shrinks 

 down towards the bottom of the case/ 3 The ro- 

 tators here spoken of are five deep lobes of the 

 rotatory organ, each having fifteen circular rows 

 of cilia one above the other, up to the points ; 

 these lobes, or arms, the animal spreads out 

 when it emerges from its case, and occasionally 

 uses them as a " prehensile instrument." They 

 are extremely beautiful and curious, and in a con- 

 stant state of activity, frequently shrinking into 

 the case, and again emerging and displaying the 

 beautiful form of the lobes. Dr. Mantell once 

 saw one he was watching, capture a Stentor by 

 the aid of these arms, but he does not say 

 whether it was eaten. They seem principally to 



