194 SALMONIA. [SEVENTH DAY. 



water is slightly coloured, or after a flood : and in 

 rain, trout usually rise better than grayling, though it 

 sometimes happens, when great quantities of flies 

 come out in rain, grayling, as well as trout, are 

 taken with more certainty than at any other time ; 

 the artificial fly, in such cases, looks like a wet fly, 

 and allures even the grayling, which generally is more 

 difficult to deceive than trout in the same river. 



PHYS. As I was looking into a ditch coming 

 down the river, which is connected with it, I saw a 

 very large eel at the bottom, that appeared to me to 

 be feeding on a small grayling : are there many of 

 this fish in the Teme, and do they breed here ? 



HAL. There are many of this fish in the river ; but 

 to your question, do they breed here ? I must answer in 

 the negative. The problem of their generation is the 

 most abstruse, and one of the most curious, in natural 

 history; and though it occupied the attention of 

 Aristotle, and has been taken up by most distinguished 

 naturalists since his time, it is still unsolved. 



PHYS. I thought there was no doubt on the 

 subject. Lacepede, whose book is the only scientific 

 one on fishes I have read with attention, asserts, in 

 the most unqualified way, that they are viviparous. 



HAL. I remember his assertion, but I looked in 

 vain for proofs. 



PHYS. I do not remember any facts brought 



