TROUT FLY-FISHING IN AMERICA 



the purpose of finding out in what time complete changes 

 in coloration will take place when trout are confined over 

 different water bottoms. 



For example : A small brook was screened in three dif- 

 ferent places ; the separate sections were all about ten feet 

 long, from three to four feet wide and about twenty to 

 twenty-four inches deep. Section i had a bright, sandy 

 and gravelly bottom; section 2 had a neutral bottom with 

 overhanging bushes ; section 3 had a dark, muddy bottom 

 with slightly overhanging banks. Three Brook Trout 

 (Salvelinus-fontinalis), all about ten inches long, were 

 caught in a pool an eighth of a mile from the screened sec- 

 tions, and were transferred to them, one trout being placed 

 in each section. 



Within two hours these trout all began to change color 

 and take on the coloration characteristic of the water bot- 

 tom of their new habitat, and in twenty-four hours a com- 

 plete change in coloration of the three trout had taken 

 place. During the next twenty-four hours no further 

 change was detected in any of the trout. 



Next, the bright trout in section i and the dark trout 

 in section 3 were carefully netted, and each was placed 

 in the other section with the result that a complete change 

 in their coloration took place within the following 

 twenty-four hours. The bright trout became dark and 

 the dark trout became bright, but the trout in section i 

 changed quicker than the trout in section 3 by about two 

 hours. 



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