REACTIONS OF A. TIGRINUM 



275 



through a bath of water in a 10-hter container. This container 

 acted as a reservoir and served to keep the pressure constant 



(fig. 1). 



The apparatus was first thoroughly tested for the effects 

 of air currents under various pressures. It was found that an 

 air current evidently stronger than that which Risser used had 

 no effect upon the reactions of the experimental animal. This 

 current could be distinctly felt on the lips or the surface of the 

 tongue of the experimenter. 



Text-figure 1 Diagram of the arrangement of the odor-stream apparatus 

 From the flask (A) the air was run through a manometer (M), and from there to 

 the odor chamber (O). A fluid, the odor of which was to be tested, was placed 

 in a vial in the odor chamber and the air bubbled through the liquid. A glass 

 nozzle, 0.5 mm. in diameter, was used to conduct the odor stream to the testing 

 chamber (7"). 



For the experiments the Amblystoma were placed in a large 

 dish, the bottom of which was covered with moist sand. Various 

 pressures between 12 and 48 mm. of mercury were tried; tem- 

 perature, 20°C. The average was 24 mm. of mercury. Air 

 under this pressure emerging through a 0.5-mm. nozzle gives 

 a displacement of 25 cc. of water per minute. 



One of the individual experiments is here given in order to 

 show the manipulation of the test substances as well as the 

 behavior of the animal under the control trials. 



Animal B: Control test with distilled water. Animal placed 

 in testing chamber and allowed to come to rest. Air current 



