TROUT FLY-FISHING IN AMERICA 



ever, depends upon the pigment colors found in each 

 species. 



Of the genus Salvelinus, the Brook Trout (species 

 fontinalis) represents the most remarkable development 

 in coloration, showing more marked changes than any 

 other species of Charr. 



And of the genus Salmo, the Rainbow Trout (species 

 irideus), and the Golden Trout (species gilberti), prob- 

 ably, everything considered, represent the greatest devel- 

 opment and changes in coloration of all the species be- 

 longing to the Salmo group. 



As the Brook Trout undoubtedly represents the most 

 remarkable development of all trout coloration, it is the 

 species I have selected to illustrate the four well-defined 

 degrees, and I can assure my readers that they truthfully 

 do so. 



Of Brook Trout coloration, William C. Harris says : 



'The coloration of this charr presents curious contrasts. Some 

 become dark and dingy as they grow old and blind; others again 

 have been found without red spots when living side by side with 

 their congeners of brilliant ones; and others are born albinos. The 

 cause of a uniform black or blackish coloration in fishes living in 

 surface streams is due to the action of the nerves of the eye on the 

 color glands, for when the fish become blind they always assume a 

 dark coloration; when the nerve of the eye ceases to act, the color 

 glands lose their motive powers. Through our eyes we receive 

 perceptions of color, shades, or tints, which are transmitted to the 

 brain; in fishes through the same medium, the nerve of the eye, 

 these impressions act upon the color glands, and are of course in- 

 voluntary and entirely beyond the control of the fish. 



"Upon dark-colored fishes living in cave-streams or under- 



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