618 JONATHAN RISSER 



INTRODUCTION 



It is the purpose of this paper to record some observations 

 and experiments on the olfactory reactions in certain amphib- 

 ians, more especially in the toad (Bufo americanus LeConte). 

 Initial experiments were tried on frogs (Rana virescens and 

 R. catesbiana), both larval and adult, but the work did not 

 prove promising and was therefore given up. 



These investigations were undertaken at the suggestion of 

 Dr. G. H. Parker of the Zoological Laboratory of Harvard 

 College and to him for his kindly interest and helpful advice I 

 wish to express my deepest appreciation. 



FOOD AND ODORS 



1 . Relation of odors to food 



There is little evidence that the relation of odors to food 

 has been taken into account in any investigation of the habits 

 of the different amphibians. In the quantitative studies of the 

 stomach contents of frogs and toads no evidence has been found 

 to show that certain foods are preferred by these animals. 

 Fischer-Sigwart ('97) believed that frogs and toads were indis- 

 criminate feeders. Needham ('05) has shown the food of the 

 bullfrog (R. catesbiana) to be extremely varied. Lockwood 

 ('83) in speaking of the toad, says "I do not believe it can smell. 

 It catches insects, but only when such probable food is in motion." 

 Knauer ('75), however, mentions cases where decomposing 

 animal food was rejected by toads after having been taken into 

 the mouth. Schaeffer ('11) found that certain caterpillars 

 were refused by frogs ia a similar manner. In both cases other 

 factors may have been of disturbing influence. Hartman 

 ('06) found no special preponderance of one species over another 

 in the insects taken from the stomach of toads collected at ran- 

 dom. Garman ('92) has records of the food of toads from which 

 one might conclude that ants were more sought after than 

 other insects. Such a condition, however, may have been due 

 to the fact that younger newly metamorphosed toads being 

 close to the ground met ants more frequently than they did 



