58 DAYS AND NIGHTS OF SALMON FISHING 



may be traced to the protection such a power affords 

 to secure them from the attacks of their enemies, 

 and exhibits another beautiful instance of the care 

 displayed by Nature in the preservation of all her 

 species. Dr. Stark often observed that on a flat, 

 sandy coast, the flounders were coloured so very 

 much like the sand, that, unless they moved, it was 

 impossible to distinguish them from the bottom on 

 which they lay.' 



" Mr. Shaw, who has the charge of the salmon 

 cruive at Drumlanrig, has observed that the Salmon 

 taken in it change their colour in consonance with 

 the turbid or refined state of the water. In the 

 experiments he has made with Parr in different- 

 coloured earthenware vessels, the change of colour 

 is perfected in the space of four minutes. If Parr is 

 taken from the dark-coloured vessel, and put immedi- 

 ately to the Parr in the light-coloured one, the 

 difference of colour between the two fish will be 

 found strikingly observable. 



" Mr. Scrope himself had observed that the Trout 

 at Castle Combe are white in a chalky spate, re- 

 suming their colour when the water clears ; and 

 that in all the rivers in which he had fished, the fish 

 are clear in a gravelly bottom, and dark in that 

 overhung with trees. All this he considered as 

 resulting from the same principle of preservation by 

 which the ptarmigan and alpine hares have their 

 colours changed with the approach of snow. 



" Notwithstanding these distinct statements by so 

 many observers in whom confidence might be placed, 

 Sir David thought that the experiments required to 



