METHODS OF FISHING 29 
kinds. In all parts of the world occur mineral and plant substances whose intro- 
duction into natural waters affects fishes. Mr. O. L. Shields, Valley Station, Ken- 
tucky volunteered information recently, “that people in a nearby county are in the 
Fia. 12. Fish-poisoning. This was the first step preparatory to poi- 
soning an arm of the Rio Chanchomayo. By means of the brush dam the 
flow of water was reduced. The actual poisoning shown in the Frontis- 
piece. 
habit of throwing walnut hulls into the creeks, and dead fish come to the surface’’. 
Furthermore, ‘this is done whenever a mess of fish is wanted.”’ South Americz 
seems to have more than a reasonable share of these deleterious substances. Bates 
