INSTINCT OF FISH. 185 



ing : to them each town, lane, or field, must 

 have a particular scent. And I have seen 

 even a blind horse, an animal in which the 

 sense of smelling is less acute, evidently 

 find his way by it to his master's house and 

 stable, which was, indeed, near a tan-yard. 

 The state of parts of water, in the sea or 

 great lakes, produced by the impregnations 

 carried down by particular streams, is much 

 more permanent than a like state in air : so 

 that though the knowledge given by the nasal 

 organs may be more easily communicated 

 at a distance by winds, yet that produced by 

 streams on the bronchiae of fishes is more 

 invariable, and a migratory fish is less likely 

 to be deceived. Yet in great floods, often 

 connected with storms, or violent motion in 

 the waters near the shore, salmon sometimes 

 mistake their river. I remember in this way, 

 owing to a tremendous flood, catching with 

 the fly a large salmon that had mistaken his 

 river, having come into the Bush, near the 

 Giant's Causeway, instead of the Bann. No 

 fish can be more distinct in the same species 

 than the fish of these two rivers, their length 



