ITS INTERNAL COLOUR. 173 



again affirm that it is induced by a species of sea- weed, 

 although they prudently forbear condescending any 

 further upon the matter. Without altogether rejecting 

 such opinions as incorrect, I cannot help asking how it 

 happens that, in absence of all marine sustenance what- 

 soever, trout and charr (themselves, it is true, belonging 

 to the same family, but inhabiting fresh-water lakes and 

 streams) acquire, in many instances, the hue referred 

 to ? That it proceeds in their case, as well as that of 

 the marine salmon, from some virtue or peculiarity in 

 the food supplied by them, is very possible. To all who 

 have studied the habits and nature of the fario or com- 

 mon fresh- water trout, it is well known that its internal 

 colour is largely affected by the quality of its subsist- 

 ence, and that this fish, when taken from a river or 

 streamlet, (where, if suffered to remain season after 

 season, it would assume no tinge of redness whatso- 

 ever,) and transferred to a lake or pond containing 

 marl or other rich food, speedily acquires the high com- 

 plexion in question, independent of other changes, else- 

 where dilated on. (See chap, i.) 



This is true, but is there nothing connected with the 

 transformation spoken of to be traced to the fish itself 

 no inherent tendency, analogous to that which flowers 

 possess, to disclose, under certain circumstances, a par- 

 ticular hue or tinge of colour? They, too (flowers), 

 depend, to some extent, for their tints and richness of 

 bloom to the sustenance they are supplied with, or, 

 what is the same thing, to the soils and climates, the 

 manures and moistures which nourish and refresh them. 

 Still this sustenance is in no case the direct occasion of 

 any particular hue disclosed by the blossom, otherwise 

 in plants that live on the same chemical substances and 

 are reared together on the same soil, the tints and 



