O they are called ; and if the almost 

 unanimous rustic opinion, with its an- 

 cient tradition and reliable witness, is 

 to be credited, such they are in very 

 truth. Indeed, there would seem to be 

 few better attested facts in the whole range of 

 natural history than the pedigree of this white or 

 brown thread-like creature which is found in sum- 

 mer shallows and pools. Go where you will in 

 the rural districts and it is the same old story. 

 " They come from horse-hairs," and in some sec- 

 tions they are destined finally to become full-grown 

 water-adders. It is commonly no mere theory. It 

 is either an indisputable fact, tested by individ- 

 ual observation, or else is accepted as a matter of 

 course, much as Pliny of old accepted the similar 

 natural history " discoveries " of his time. He 

 says, for example, on a similar subject, " I have 

 heard many a man say that the marrow of a man's 

 backbone will breed to a snake. And well it may 

 so be, for surely there be many secrets in nature 



