328 JOSEPH PETERSON 



to those who had overlooked the obvious imperfections of such 

 experiments as they had been carried out. With improvement 

 in methods of determining reactions to specific sounds, however, 

 the problem may be attacked with some degree of success; but 

 there still remain grave difficulties in connection with the opera- 

 tive technique. 



Yerkes found that the dancing mouse is deaf to all sounds, 

 except for a few days early in life. 4 The examinations of the 

 cochlea of this animal by such investigators as Rawitz, Cyon, 

 Alexander and Kreidl, and Kishi are not very satisfactory from 

 a number of standpoints. For example, the fitness of structures 

 in the cochlea for resonance of tones, a difficult matter to deter- 

 mine, is a question that is not answered. The recent experiments 

 of Hunter, checked by various controls, seem to indicate that 

 the rat is deaf to tones in the lower end of the scale — possibly 

 to all tones — while it hears noises of the same predominant 

 pitches. Hunter suggests that if after all " there is a sensi- 

 tivity to tonal stimuli as here tested, then, for the rat, tones 

 and noises are very different classes of stimuli." 5 Miss Barber, 

 working under Hunter's supervision,, has found similar evidence 

 for the rat's deafness to tones/ and has suggested 7 that her own 

 and Hunter's results, indicating a sensitivity to noises and an 

 insensitivity to tones, ' may point to separate bases for the 

 perception of noise and tone." What may be the nature of 

 these bases is not conjectured. It is on this point that I wish 

 to make a suggestion. 



If Hunter's results prove to be correct, the white rat should 

 furnish us valuable data toward settling the question as to 

 how the ear analyzes the complex vibrations of the air waves; 

 for there can be little doubt that tone perception by the ear 

 follows the same principle in the higher animals as in man. Why 

 the rat fails to hear tones and yet hears noises should be dis- 

 coverable somehow, and the answer will likely require careful 

 anatomical as well as experimental work. 



Personally I do not believe that in animals just above the 

 rat in hearing — animals hearing both -noises and tones — sepa- 

 rate structures are involved in noise and in tone perception. To 



4 The dancing mouse, 1907, 52-92. 



5 Op. ciU, vol. V, 327. 



6 The localization of sound in the white rat, Jour. An. Behavior, 5, 1915, 292-311. 

 'Ibid., 311. 



