84 A THEORY AS TO THE RISE 



Blue in the air, but the few solitary rising fish took 

 no further notice of the Iron Blue Duns, which rapidly 

 disappeared. I tried it, however, for some time longer, 

 but eventually I replaced my Grannom, and caught 

 several other trout before going home. 



Before putting on the Grannom, however, I ex- 

 amined the food in the latest caught fish, and found 

 that the upper part of its gullet contained a great 

 number of nymphse or pupae of the Iron Blue in their 

 most advanced stage, several specimens having their 

 wings already unfolded. 



I am inclined, therefore, to think that, owing to 

 some altered condition of the water or atmosphere, 

 the pupae of the Ephemeridae, moved by one of those 

 mysterious impulses which occasionally influence the 

 insect world, had risen to the surface to assume their 

 sub-imago existence, and that this general move- 

 ment was followed by the excitement of the fly feeding 

 fish. 



Since that occasion I have corroborated the theory 

 I then formed by examining the food of the fish caught 

 during the rise, and have found that it consists, as a 

 rule, of a greater number of the pupae than the sub- 

 imago of the existing hatch. I have also noticed the 

 trout during a rise taking the pupae below the surface, 

 and have seen the trout following pupse up, and taking 

 them just as they reach the surface of the water. 



I do not claim that this suggestion will account for 

 all the general rises peculiar to trout, but I think that 

 in many cases it will be eventually proved to be caused 



