181^ SALMONIA. 



haunt very deep water, which even in summer 

 is of low temperature, approaching to 40°, 

 and contains httle or no vegetable food or 

 insects, w^hich the smaller fishes search for ; 

 and the larger fishes follow the smaller. It is 

 however possible, that in winter, all fish fond 

 of heat will seek water rather deeper than in 

 summer ; and char and umbla, in lakes, are 

 usually found^in the deepest parts, being fond 

 of cool water ; and they come to spawn when- 

 ever tiie shallow water of the lakes becomes 

 cool, in October or November. We cannot 

 judge of the senses of animals that breathe 

 water, — that separate air from water by their 

 gills; but it seems probable, that, as the qua- 

 lity of the water is connected with their life 

 and health, they must be exquisitely sensible 

 to changes in water, and must have similar 

 relations to it, that an animal with the most 

 delicate nasal organs has to air. A vulture 

 or a dog scents not only particular food and 

 particular game at great distances, but even 

 makes of the smell a kind of language ; and 

 I doubt not, that when dogs, that have been 

 blindfolded and carried away from their 

 home, return to it, it is by the sense of smell- 



