32 HAROLD SAXTON BURR 



rial. When on the other hand, the olfactory nerves were severed, 

 no positive reaction occurred. Since then Copeland ('12) has 

 confirmed Parker's results with other fish. 



Reese ('12) was the first to attack the problem in Amphibia. 

 Working with Diemyctylus, he showed that the adults would 

 follow and snap at moving bits, whether food or not. They 

 would also make characteristic snapping movements when beef 

 juice was squirted over the external nares. No attempt was 

 made to control the sense of sight. He tried to control the sense 

 of taste, however, by introducing a bit of cotton soaked in cocaine 

 into the mouth. The results were conflicting and inconclusive. 

 Animals in which the olfactory nerves were cut failed to respond 

 to stimulation. 



Copeland ('13) repeated the experiments of Reese, using more 

 exact methods. Control of the visual sense was accomplished 

 by stimulating the olfactory epithelium from a motionless source. 

 By dividing the total reaction into two periods, during the first 

 of which an approach was made to the source of the stimulus, 

 and during the second, the object was snapped at or taken into 

 the mouth, he came to the conclusion that the approaching re- 

 action was due entirely to the sense of sight, the seizing alone to 

 the sense of smell. 



The object of the following experiments was to test this prob- 

 lem in Amblystoma, comparing the reactions of the normal 

 larvae to food with those of the noseless. 



There are in general three groups of sensory organs which 

 conceivably may receive stimuli from the source of olfactory 

 stimulus. These are, in the order of relative importance, the 

 eyes, the taste buds and the lateral line and general cutaneous 

 systems. 



Stimulation of the latter systems can be eliminated by using 

 a motionless source, since such stimulation is brought about by 

 currents in the water. Such a source would at the same time 

 give relatively little stimulus to the visual sense. 



Control of the stimuli of the taste buds is hardly practicable 

 experimentally without rather serious operations on adult forms. 

 Fortunately it is known that the sense of taste is operative over 



