144 DROPS OF WATER. 



watched, will be found gradually to expand, and 

 to stretch itself far beyond the edge of the case, 

 and then to unfold its curious, rotatory organ, 

 which is divided into six lobes, each provided 

 with many cilia. A current is then observed in 

 the water, though the cilia are not seen to move ; 

 small objects are drawn into the mouth very 

 rapidly, and swallowed, to be ground down by 

 the chewing apparatus, which may be observed 

 constantly at work. When danger approaches, 

 the creature contracts suddenly, and is safe 

 within the case in an instant ; this protective 

 case is so exceedingly transparent, that even the 

 brightest light will fail to render it visible, unless 

 it is partially covered with loose matter which 

 has been drifted to it by the water; or it may 



