THE SYSTEM OF ARTIFICIAL FLIES. 13 



the artificial for the natural fly, the formalists 

 argue that the one should be an exact counterpart 

 of the other, ignoring the fstct that the two insects 

 are offered to the fish under entirely different condi- 

 tions. The artificial fly is presented under water 

 instead of on the surface ; wet instead of dry ; 

 and in brisk motion up, down, or across stream, 

 instead of passively floating. No doubt if the 

 flies could always be kept dry and passively 

 floating that is, as they are seen in nature the 

 exact imitation theory would (though only up to 

 a certain point) be sound enough ; but as in 

 practice this is impossible, we are perforce driven 

 to artificial expedients to extricate us from the 

 " unnatural" dilemma. Thus at the very outset 

 we find ourselves compelled to simulate life instead 

 of death in our flies ; and for this purpose impart 

 to them a wholly unnatural motion whilst 

 swimming : again, because " fluffy" materials when 

 wetted lose much of their strength of colour, fly 

 bodies are constantly made of hard silk instead of 

 soft dubbings ; and as it is found that a naturally 

 proportioned insect is deficient in "movement," an 

 unnatural quantity of legs (hackles) are added to 

 it in the smaller species the wings being often 

 omitted entirely. In short, we are launched upon 



