OTHER THEORIES. 1193 



compound movement must affect the membrana basilaris. Even supposing 

 Hurst's theory is correct, this movement, or its effects, must pass up the mem- 

 brane of Reissner and down the basilar membrane, but how does this explain 

 the fact of analysis 1 Further, as Hurst himself observes, according to his theory, 

 the " region of the cochlea where the stimulation of high tones occurs is near 

 the apex ; low ones producing a stimulation, near the base." This is contrary 

 to the generally accepted view, founded mainly on pathological evidence, that 

 the seat of stimulation by high tones is in the basal region, while that of low 

 tones is in the apical, and Hurst's explanation appears to me insufficient. 



More recently an ingenious view has been set forth by Max Mayer, 1 in 

 which the principle of sympathetic vibration is also discarded. Mayer sup- 

 poses a wave to travel up the scala vestibuli, and to press the basilar membrane 

 downwards. As it meets with resistance in passing upwards, its amplitude 

 diminishes, and thus the distance up the scala through which the wave pro- 

 gresses will be determined by its amplitude. Further, the wave during its 

 progress will irritate a certain number of nerve terminations ; consequently, a 

 tone of feeble intensity (amplitude) will irritate only the fibres lying near the 

 fenestra ovalis a certain number of times per second, while, if the same note be 

 sounded loudly, the wave will travel further up the scala and irritate a large 

 number of nerve fibres the same number of times per second. Thus the pitch 

 will be the same, but the intensity or loudness will be greater. Pitch, according 

 to this view, will depend on the number of stimuli per second, while loudness 

 will depend on the number of nerve fibres irritated. How can such a 



FIG. 425. Compound wave form according to Max Mayer. 



mechanism act as an analyser 1 Suppose a compound wave (such as shown 

 in Fig. 425) to travel up the scala vestibuli, the two tones producing such 

 a curve have a vibration frequency of the ratio 2 : 3, and it will be 

 observed that there are three maxima and three minima. Now, as the 

 wave passes up the scala, the parts shaded horizontally will die away first, 

 and there will be left two maxima and minima. Let the wave travel still 

 further up, and the part shaded vertically will disappear, leaving only one 

 maximum and minimum. Finally, as the wave travels further, this also will 

 disappear. Thus the nerve fibres in these different portions of the basilar 

 membrane will be affected, and each will be affected a different number of 

 times per second. The compound tone will therefore be resolved into three 

 tones having vibration frequencies in the ratio of 3:2:1. According to 

 Mayer, when two tones of the relationship 3 : 1 are sounded, we actually 

 hear these tones of the relationship 3:2: 1, the tone indicated by 1 being 

 the so-called differential or beat tone. Similarly, if two tones of the ratio 9 : 4 

 be sounded, we resolve into tones of the ratio 9:4:1 (the 1 being obtained by 

 4x2 = 8, and 9 8 = 1); and if we construct a curve in the same way as 

 shown in Fig. 425, and cut off successive maxima and minima, we have the 

 same ratio of maxima and minima, namely, 9:4:1. Finally, Mayer, as 

 the result of experimental inquiry, denies the existence of combination 

 tones, the vibration frequencies of which are the sum or the difference 



1 Ztschr. f. Psychol. u. Physiol.. d. Sinnesory., Leipzig, Bd. xvi. and xvii. ; also 

 Verhandl. d. physiol. Gesellsch. zu Berlin, February 18, 1898, S. 49 (in Arch. f. Physiol.). 



