The Journal of 

 Comparative Neurology and Psychology 



Volume XV 1905 Number 4 



THE SENSE OF HEARING IN FROGS. 

 By Robert M. Yerkes. 



From the Hari'ard Psychological Laboratory . 



With Seven Figures. 



CONTENTS. 



I. Historical Setting of Subject 279 



/. Hearing in frogs and fishes . . . . . . 279 



2. The ear of the frog ........ 282 



J. Problems ......... 285 



II. Reactions of Frogs in Nature to Sounds. . . . 286 



III. The Influence of Sounds on Reactions to Other Stimuli 288 



/. Infiitence of sounds 071 respiration and visual reactions . 288 



2. Infiuence of sounds on tactual reactio7is .... 288 



IV. Hearing of Frogs in Air and in Water .... 296 

 V. The Range of Hearing 298 



VI. Relation of the Ear to Reaction to Sound . . . 301 

 VII. Summary and Conclusions 303 



I. Historical Setting of Subject. 



/. Heanng in frogs and fishes. The question of the ex- 

 istence of a sense of hearing in frogs is not, as in fishes, an 

 historical problem. For while the question, Do they hear? has 

 been asked repeatedly concerning fishes, and answered as often 

 with 'No' as with 'Yes', students of sense-physiology and 

 animal behavior have assumed, without investigation, that frogs 

 are stimulated by so and. This unquestioning belief in the ex- 

 istence of hearing in frogs is doubtless due to the presence of a 

 prominent ear drum and the ability to produce sounds. Frogs 

 differ from fishes, with respect to the structure of the ear, in 

 that they possess an ear-drum together with a bone which con- 



