136 THE FRESH-WATER EEL 



which swings equally from either extremity. 

 Truly nature's machinery is no less accurate. 

 The following is a still more remarkable 

 instance of a creature whose innate sense of 

 direction leads it to isolated water-holes of 

 whose whereabouts it can by no possibility 

 have conscious knowledge. This is the fresh- 

 water eel, of whose life-history and mode of 

 propagation nothing was known until quite 

 lately. It was known, however, that eels 

 inhabited rivers and ponds, and in these situa- 

 tions it was supposed they bred ; but no trace 

 of the ova was discovered either in the water 

 or in the fish itself, a circumstance which 

 apparently gave rise to a quaint superstition, 

 viz., that eels were produced from horsehairs ! 

 Incredible as it may sound, such was the 

 common belief even among educated people. 

 The notion no doubt originated from the 

 fact of the existence, in ditches and ponds, of 

 a kind of water-worm (Gordius aquaticus) 

 which has nothing to do with eels, but cer- 

 tainly has the appearance of an animated 

 horsehair. However, it has now been ascer- 

 tained that though eels live, it may be for 

 years, in fresh water, they are really native 

 of the sea. In order to propagate their species 

 a certain proportion of eels go down yearly to 

 the sea to spawn. In the spring, the young, 



