OTHER THEORIES. n 9I 



equally to every note, and the hair cells transform sound vibrations 

 into nerve vibrations, or impulses, similar in frequency, amplitude, 

 and character to the sound vibrations. There is thus no analysis 

 of sound in the peripheral organ. Now, there can be no doubt 

 that a wire connecting two telephones, or connecting a microphone 

 transmitter with a telephone receiver, will carry a series of electric 

 impulses, or waves, corresponding in number, form, and character to 

 the waves of musical tones falling on the microphone or first telephone. 

 Thus the tones corresponding to the vibrations of the disc of a phono- 

 graph may be transmitted to a telephone, and be there reproduced 

 with remarkable fidelity. The analogy, therefore, between the fibres of 

 the auditory nerve and such a wire is admissible. But the analogy breaks 

 down when we consider the fact of analysis. The distal telephone does not 

 analyse the waves reaching it, and if its movements could be graphically 

 recorded, a matter merely of experimental difficulty, they would 

 reproduce exactly the waves falling on the proximal telephone or the 

 microphone transmitter. When we listen to the distal telephone, we 

 hear all the sounds corresponding to these waves, and we can at once 

 analyse these, sifting the one from the other; that is to say, in the 

 experiment, the ear is, after all, the ultimate analyser. Further, one 

 can conceive a device by which the waves of sound given forth by the 

 second telephone might be analysed, but such a device could only be 

 constructed on the principles of sympathetic resonance. 



Waller 1 proposes to explain the mechanism of the cochlea as 

 follows : The basilar membrane, as a whole, vibrates to every tone, thus 

 repeating the vibrations of the membrana tympani ; and since the hair 

 cells move with the basilar membrane, they produce what may be called 

 pressure patterns against the tectorial membrane, and filaments of the 

 auditory nerve are stimulated by these pressures. With the exception 

 of the use of the phrase " pressure patterns," this is much the same as 

 the view of the mechanism of the cochlea already described, except that 

 I hold that, in conformity with Ohm's law, there is an analysis by the 

 cochlea, whereas, according to Eutherford, the tones are not analysed by 

 the cochlea, but by the brain ; while Waller's view admits of a certain 

 degree of peripheral analysis (pressure patterns), but also relegates ulti- 

 mate analysis to the brain. 



Judging from the effect of rapid stimuli sent along a nerve to 

 a muscle, it might be supposed that a number of nervous impulses, 

 corresponding to a tone of high pitch, could not call forth a response 

 from the terminal apparatus in the nerve centre at the same rate. 

 For when more than about thirty stimuli are sent to a muscle, 

 it passes into a state of complete tetanus, and no matter how many 

 more stimuli per second are sent along the nerve, the muscle re- 

 mains in the same state. As Eutherford, 2 however, has pointed out, 

 although the effect upon the muscle, so far as contraction goes, is the 

 same no matter how rapid the stimuli sent to it may be, provided there 

 are more than 30 per second, yet on listening over the muscle while 

 the nerve is being stimulated, a sound is heard, the pitch of which 

 varies according to the number of stimuli per second sent into 

 the nerve. This had been already pointed out by Loven, who 

 regarded the notes produced as being due to electrotonic variations 

 in the nerve. Thus, when forty stimuli per second are used, a tone 



1 Proc. Physiol. Soc, Jan. 20, 1891. 2 Loc. cit. 



