54 OBSERVATIONS OF SIR D. BREWSTER. 



the waters in which they are found. The final reason 

 for this may be traced to the protection such a power 

 affords to secure them from the attacks of their ene- 

 mies, 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 im- 

 possible 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 ves- 

 sels, the change of colour is perfected in the space of 

 four minutes. If Parr is taken from the dark-coloured 

 vessel, and put immediately 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, resuming 

 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 prin- 

 ciple 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, 



