62 Book of the Black Bass. 



In the young of the large-mouth bass the color is also 

 greenish but darker, with a blackish band along the lateral 

 line, and clusters of dark spots above and below. The iris 

 is golden. The base and tip of the caudal fin is some- 

 what paler than in the middle. 



Those who keep their fish alive in fish-cars or live-boxes, 

 or by the more reprehensible practice of stringing the 

 fish, will observe that however different in coloration fishes 

 of the same species may appear when first caught, that 

 after being subjected to the same conditions for a few 

 hours they will all exhibit the same coloration. 



A familiar instance of the change of coloration due to 

 environment, or change in the condition, character, depth 

 or temperature of the water, or in the food, is seen in the 

 Canadian sea-trout. This is merely the brook-trout that 

 has become anadromous and runs to the sea. When it re- 

 turns, in the spring or early summer, to the mouths of the 

 streams, it is, like most marine fishes, of a bright, silvery 

 appearance; but after being in fresh water a short time it 

 again takes on the characteristic colors and spots of the 

 brook-trout. I have taken them in both their salt-water 

 and fresh-water colors, and in a transition stage, in the 

 Eestigouche Eiver, between Matapedia and Campbellton, 

 Xew Brunswick. 



The external coloration of fishes depends on the pres- 

 ence of variously-colored pigment-cells in one or both lay- 

 ers of the skin. These pigment-cells are said to be under 

 the influence or control of the nervous system, and are 

 thus able to cause changes of color which may be rapid or 

 temporary, or more or less permanent. 



In some fishes, as the black bass, the change in colora- 

 tion is involuntary, and is, without much doubt, occasioned 

 by an increase or decrease in the number of the different 



