164 THE TROUT. 



Besides larvae, insects, worms, fresh-water mollusca, 

 and smaller fishes, trouts feed on frogs, water lizards, 

 and sometimes, it is said, on toads, though from the 

 acrid secretion that exudes from the skins of the latter, 

 which they seem to be preparing when they swell 

 themselves up, and which is probably their only means 

 of defence, they cannot be either palatable or whole- 

 some. It seems doubtful whether trout, or any of the 

 other fishes that swallow their food without mastica- 

 tion, have much, if any, sense of taste. On their 

 tongues, or the internal surface of their mouths, there 

 is nothing analogous to the papillce on the tongues of 

 the mammalia ; and it may therefore be concluded 

 that they have no means of discriminating the qualities 

 of the substances on which they feed. Some writers have 

 even gone so far as to conclude that, as the fishes have 

 no means of judging of the substances that enter their 

 stomachs, they cannot be poisoned in that way. Per- 

 haps that may be going a little too far ; but certainly 

 they admit of a wonderful latitude of aliment, and are 

 certainly much less affected by any change of it than 

 quadrupeds or birds. The organs of respiration seem 

 to be the only delicate or sensitive part of fishes ; as it 

 is always in the gills that they are immediately affected 

 by impure waters. 



Though there has been a good deal of investigation 

 of the subject, and organs of hearing, of some sort or 

 other, have been found in most species of fishes, yet 

 they are simple and obscure, as compared with those of 

 land animals; and hence we may conclude that their 

 sense of hearing is proportionably feeble. That they 

 are affected by loud sounds has been proved by ex- 



