THE TROUT 65 



with muddy or peaty bottom the Trout are of a 

 darker colour generally, and when enclosed in caves 

 or holes they may assume an almost uniform 

 blackish coloration." 



Professor Poulton has adduced some evidence 

 that the change of colour in response to a changed 

 environment is effected through the eye ; in a clear 

 chalky stream a few Trout were seen to be much 

 darker than the rest, and much more conspicuous ; 

 these were found to be blind, and in consequence 

 were ill-fed and lean. 



The inconstancy of the colours of Trout is well 

 exemplified in the following instances : Percy 

 St. John (Wild Sports of the West} described a 

 lake in Monaghan, a long irregular sheet of water 

 of no great depth, bounded on one side by a bog, 

 on the other by a dry and gravelly surface. On 

 the bog side the Trout were said to be of the dark 

 and shapeless kind peculiar to many loughs, whilst 

 on the gravel they were of the beautiful and 

 sprightly variety which generally inhabits rapid 

 and sandy streams. Day gives an account of two 

 lochs in Inverness-shire which were stocked at the 

 same time from Loch Morar ; a few years after- 

 wards the Trout in the larger lake, which had a 

 sandy and weedy bottom, had golden sides, were 

 covered with numerous red spots, and had white 

 flesh ; in the smaller lake, where the water was dark 

 coloured and the bottom rocky, they were described 

 as having the head nearly black, the sides yellowish 

 olive, about ten red spots and fourteen black ones 

 present on each side, and the flesh pink. 



The River Smoo in Sutherlandshire plunges 

 through a hole in the roof of a cave and falls about 



