132 A PRINCIPLE ILLUSTRATED. 



selection of particular species. Well, at the time 

 in question, the line of fish in the stickle under 

 the opposite bank aforesaid, are gastronomically 

 moved towards a certain species of the class of 

 flies referred to, every one of which is charac- 

 terised by the habit of floating upon the surface of 

 the water, in reverse of the phryganidas, which 

 generally hover above it, and flit about the 

 banks. Impelled by some peculiarity of the 

 atmosphere, or by some other cause which we 

 cannot, and need not if we could, explain, the 

 fish have come close to the surface to watch for 

 their prey, which can thus be easily seized as 

 the victims float along, without further trouble on 

 the part of the fish than gently lifting their 

 mouths above the water. Now, the angler's fly 

 is wet and heavy, and, thrown from the other 

 side, has a certain weight of line in addition. So, 

 as it is not in the nature of things that this 

 soaked artificial fly can swim upon the surface as 

 the natural ones do, it follows the alternative and 

 sinks below the rising fish, the notice of which it 

 entirely escapes, because they happen just then to 

 be looking upwards for the materials of their 

 meal. Let a dry fly be substituted for the wet 

 one, the line switched a few times through the 

 air to throw off its superabundant moisture, a 



