OLFACTORY REACTIONS IN AMPHIBIANS 



629 



and allowed freedom of movement. For control tests there was 

 provided a duplicate of the tube, d, which could be connected 

 directly with B; thus avoiding any possible errors by contami- 

 nation from the material in D. The chamber, E, was an open 

 cylinder, the lower end resting in a shallow vessel containing 

 soil easil}'^ changed and moistened. To eliminate other dis- 



P^ig. 1 A, reservoir; B, air chamber; C, odor chamber; D, vial; E, experiment 

 chamber; F, lamp; a, water tube A io B;h, airtube S to C; c, outlet tube for odor 

 stream; d, nozzle tube for chamber E', e, vessel containing sand; x, y, clamps. 



turbing factors the cylinder was covered with black cloth. The 

 illumination of the chamber, E, was by an electric lamp of 8 c.p. 

 This was of advantage in orientation; as the toads are positively 

 phototropic (Pearse '10). 



The apparatus was arranged near the water supply in a base- 

 ment room from which daylight could be excluded. Several 

 other chambers similar to E were provided in order to adjust 



