OLFACTORY REACTIONS IN AMPHIBIANS 625 



In the presence of the Uving larvae, no attention was paid to 

 motionless artificial larvae, but if these were set in motion they 

 were sometimes taken. 



Effects of the substances used in these experiments may 

 be summed up as follows: The odor of the iodine solution wag 

 not deterrent in any manner; the after-effect seemed to be 

 more disturbing in the mouth region than did that of other 

 substances. Oil of pennyroyal and oil of rose geranium when 

 they touched the lips led to wiping the mouth-parts with the 

 forefeet. No similar effect was noticed from clove oil, cedar 

 oil, and bergamot oil. When bisulphide of carbon was applied 

 to the mealworms, the toads gave some evidence of discomfort, 

 gulping several times in succession after having taken larvae 

 prepared with this substance. Aniline oil did not cause any re- 

 actions that seemed to result from stimulation of the mouth- 

 parts, nor was it repellent because of its odor. 



FOOD AND DARKNESS 



The diurnal retreat of the toad into dimly illuminated places 

 and its habit of feeding in the night are well-known. Frogs 

 on the contrary are most active during the daytime. In con- 

 nection with the feeding experiments on the toad it was desir- 

 able to know what degree of darkness was prohibitive to its 

 finding food. Are other stimuli present, do smell, hearing and 

 touch share in the reactions of seeking food? 



1. Materials 



The same individuals that were used in the previous experi- 

 ments were used in these trials. The toads appeared to be 

 in normal condition, giving no evidence of having undergone 

 any untoward experiences. No changes were made in the 

 care given the toads. The experimentation was done in a 

 photographic dark-room with controllable illumination. 



The experimentation chamber was a box, 30 inches long, 

 20 inches wide, and 8 inches high. Loam and leaves had been 

 allowed to remain in the box for some days, thus giving the cham- 

 ber some semblance to the toad's natural habitat. 



