174 POULTRY DISEASES 



swings shut passing over the pivot and the shorter 

 end of the lever. When the door is shut the 

 lower end of the lever rests on the floor of the 

 nest, and the short end acts as a stop on the in- 

 side, preventing another hen from crowding into 

 the nest. When the egg is gathered the trap nest 

 is set again by raising the long end of the lever 

 and propping back the door. The two right-hand 

 nests in -the upper sketch show the position of 

 the doors and levers before the hen enters. The 

 other nests show the traps closed. 



