122 Marvels of Pond-Life. 



guard the way, and exercise some choice as to what 

 particles shall be permitted to pass on. This organ is 

 called the epistome, from two Greek words, signifying 

 ^' upon the mouth/^ 



If the cell is an old one, it may be covered with so 

 much extraneous matter as to obscure the economy 

 within j but we are fortunate in having a transparent 

 specimen before us, through which we can see all that 

 goes on. The alimentary tube, after forming a capacious 

 cavity, much longer than it is broad, turns round and 

 terminates in an orifice near the mouth, and just below 

 the integuments. When refuse has to be discharged, 

 this orifice is protruded; and after the operation is 

 over, it draws back as before. Long muscles, composed 

 of separate threads or fibres, pull the creature in and out 

 of its cell, and at the part where the stomach ends, and 

 the intestine turns round, is attached a long flexible 

 rope, called the funiculus, which goes to the bottom of 

 the cell. The passage of the food down to the stomach, 

 its digestion, and the eviction of the residue, can all be 

 watched ; and when a large morsel is swallowed, the 

 spectacle is curious in the extreme. 



One day a polyzoon caught a large rotifer, {R. vul- 

 garis,) which, with several others of its tribe, had been 

 walking over the coenGecium, and swimming amongst 

 the tentacles, as if unconscious of danger. All of a 

 sudden it went down the whirlpool leading to the mouth, 

 was rolled up by a process that could not be traced, 

 and without an instant's loss of time, was seen shooting 

 down in rapid descent to the gulf below, where it looked 

 a potato-shaped mass, utterly destitute of its charac- 



