90 AMERICAN FISHES. 



utely examined the water, and the materials, which were the same as 

 his own, and, very much surprised, said, i I have lost my labor and 

 my money, for the air of England does not permit us to make good 

 carmine.' ' Stay,' says the Frenchman, ' do not deceive yourself; what 

 kind of weather is it now ?' ' A bright sunny day,' said the Eng- 

 lishman. ' And such are the days,' said the Frenchman, i on which 1 

 make my color. Were I to attempt to manufacture it on a dark or 

 cloudy day, my results would be the same as yours. Let me advise 

 you, my friend, to make your carmine on bright sunny days.' ' I will/ 

 says the Englishman, c but I fear I shall make very little in London.' ' 



Now this anscdote may be depended upon; for a person so distin- 

 guished as a chemist and natural philosopher as Sir Humphrey Davy, 

 would not have related a story in regard to the effect of light, which 

 was contrary to truth, or which he did not directly know to be true. 



And if the effect of sunshine is so great on color, as that the in- 

 crease or decrease of its brilliancy should cause a totally different 

 result to follow from the combination of precisely the same chemical 

 ingredients, it will readily follow that much more effect will be pro- 

 duced by its excess in one case, or almost total exclusion in another, 

 upon hues so changeful as those which glitter on the scales of a fish. 



That in a pure limpid rapid stream, rushing over a bright gravelly 

 bed, through open fields, where no envious boughs intercept the sun- 

 light, and in a dark turbid pond, the waters of which are saturated 

 with the draining of peat-bogs, or with the juices of decomposed vege- 

 table matter, and overshadowed by thick evergreen umbrage, the light 

 even of the most gorgeous noon will be transmitted in very different 

 degrees, and produce very different effects both of color, heat and 

 radiance, any person can judge, who will observe the sunbeams as they 

 fall through a sheet of pure plate-glass, or a thick green bull's-eye ; 

 and that the consequences may easily be as they are stated above, he 

 will, I think, be satisfied. 



Now, in the first place, analogous to this, and in corroboration of 

 this view of the subject, I will remark here, that one of the principal 

 external differences between the American and the European Trout, 

 is precisely as might be expected under the views taken above. The 

 climate here being far more sunny, the atmosphere drier and more 

 transparent, and the weather more constant and lightsome, we find that 



