520 



William Morton Barrows 



through the trough had a chance to enter the charged trap or the 

 check trap or to react to the odor issuing from the former. 



The plan and elevation of the apparatus used are shown in Figs. 2 

 and 3, respectively. On a wooden base A, some 30 cm. in length 



Fig. 2 



Fig. 3 

 Figs. 2 and 3 Plan and elevation of apparatus used in testing the reactions of Drosophila to odors. 

 A, wooden base; B; leaden trough; C, zinc slide for closing exit from the receiving chamber, E; D, glass 

 plate; E, inverted glass dish forming a receiving chamber; F, inclined way; G, inverted glass dish form- 

 ing a collecting chamber; H, hole in glass plate serving as entrance to collecting chamber; / /' , entrance 

 tubes to trans; 7. suction tube. 



and 12 cm. in width, was mounted a leaden trough B, which was 14 

 cm. long and about 2.5 cm. broad except at the far end (right in the 

 figure) where it expanded into a chamber 3 cm. square. The 



