12 A BOOK OF THE RUNNING BROOK: 



water any time or is exhausted, a fact known 

 to the street vendors of live eels, who therefore 

 are careful to cover their eels with sand to hide 

 the caudal pulsations. Dr. Marshall Hall, 

 who in 183 1 discovered this secondary heart, 

 says of it that "the action of this caudal 

 heart is entirely independent of the pulmonic 

 heart ; while the latter beats sixty, the former 

 beats one hundred and sixty times in a minute. 

 It continues for a very long time after the 

 influence of the pulmonic heart is entirely re- 

 moved." It is probably owing to this caudal heart 

 that the eel's tail is so highly sensitive and so 

 strong. Eels can use their tails almost like hands ; 

 for instance, if confined to a tank or bucket, 

 they will grasp the edge with this hand-like 

 tail, and by its help lift themselves bodily over. 

 Eels are very clean feeders ; if possible, they 

 like their food alive, and in all cases it is most 

 essential that it should be fresh. Even the 

 slightest taint is too much for their keen sense 

 of smell and taste. They are sometimes seen 

 cropping the leaves of watercresses, and other 

 aquatic plants, as they float about in the 

 water; but as a rule their food is altogether 



