XI 



AN INSECT LAW-BREAKER 



"It is probable," said the Professor as we all 

 crowded around him on the rugged bank of Fall 

 Brook, "that those rocks over there are just cov- 

 ered with Hydropsyche nets." 



We stared at the little cataract at which he 

 pointed and could see only the hurrying water and 

 the rather dirty rocks over which it flowed. We 

 waited for the "Man with the Boots" to go out 

 and show us just where to look. "The Man with 

 the Boots" always seemed to know just what to 

 look for and where to look. We learned after- 

 ward that this knowledge was not intuitive but came 

 from taking frequent walks with the Professor on 

 holidays and during vacation. We admired him 

 the more and envied him his privileges. He was 

 useful, too, and his rubber boots were kept wet 

 most of the time on a trip like this. 



We went nearer and could see that the dirt 

 clinging to the stones in the current must be held 

 there by something; mere dirt and rubbish would 

 have been washed away. In the laboratory we had 

 that very morning admired the trap of the net- 

 building caddice-worm, called by his intimates 

 "Hydropsyche." The nets we had seen were clean, 

 funnel-shaped affairs of woven silk firmly attached 

 to stones. At the small end of the funnel was a 



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