58 Book of the Black Bass. 



gated naturally in the stream. The trout which were 

 reared artificially were kept in covered plank flumes, and 

 in open ponds, and were fed principally on chopped liver; 

 those in the ponds got some addition to this fare, however, 

 in aquatic flies, insects, etc. The stream contained a great 

 many crawfish, which did much damage to the dams and 

 ditches of adjacent cranberry marshes. Frequently visit- 

 ing this establishment, 1 was struck with the remarkable 

 difference in the colors of the trout in the flimies, in the 

 ponds, and in the stream. Those in the flmnes were quite 

 dull in appearance ; those in the ponds were brighter ; while 

 those in the stream were very highly colored, caused, per- 

 haps, by their feeding upon the crawfish with which the 

 stream abounded. The dull color of the trout in the flumes 

 was partly owing to their shaded condition. 



Xot only does the character of the food seem to influ- 

 ence the external coloring of the salmon family, but the 

 tint of the flesh, if I may so call it, may also be afiected 

 by the same cause ; thus, Louis Agassiz states that the most 

 beautiful salmon-trout are found in waters which abound 

 in Crustacea, direct experiments having shown to his satis- 

 faction that the intensity of the red color of their flesh 

 depends upon the quantity of Gammaridce (shrimp) which 

 they have devoured. 



The red-throat trout (Salmo clarJcii lewisi) of Henrys 

 Ijake, at the head of Snake Eiver, in Idaho, and likewise 

 those of Soda Butte Lake in the Yellowstone National 

 Park, are noted for the deep red tint of their flesh — as 

 red as that of the Chinook salmon — and on this account 

 are erroneously called " salmon-trout." The probable 

 cause of their red flesh may be found in the extraordinary 

 abundance of fresh-water shrimp that inhabit both lakes, 

 which are of similar character, being shallow, with muddy 



