650 JONATHAN RISSER 



not affected by section of the ophthalmic branch of the trigeminal 

 nerve. 



7. Under circumstances allowing discrimination, the tadpoles 

 of the toad prefer animal foods. 



8. Such discrimination appears to rest upon the appropriate 

 stimulation of the olfactory receptor. 



9. Tadpoles of the toad show by proper reactions that animal 

 food is recognized, although not visually perceptible. 



10. The receptor organ so stimulated must be a distance 

 receptor and thus is olfactory in function. 



11. In the metamorphosed toad the visual stimulus is the 

 principal and guiding factor in procuring food. Therefore, 

 it is inhibitory in relation to other stimuli and their resultant 

 reactions. 



Postscript. Since the preparation of this paper, Copeland 

 has published in The Journal of Animal Behavior, vol. 3, pp. 

 260 to 273, an account of the olfactory reactions of the newt 

 Diemyctylus and has shown that this amphibian can scent food 

 under water as a fish does. 



