HALLOWELL DAVIS 71 



to be the case, it may be simpler to speak only of a direct modulation of the 

 potential of the 'battery' by mechanical movement, rather than of a battery of 

 constant EMF and an anatomically distinct 'variable resistance microphone.' 

 The final result, however, would be much the same wherever the 'battery' is 

 located. There would still be a variation in current flow through the base of the 

 hair cells and on through the nerve endings and fibers, that could serve as the 

 stimulus to initiate nerve impulses. Either concept provides a biological 

 amplifier which utilizes a pre-existing store of readily available energy. This 

 electrical energy is valved or modulated by the microscopic or sub-microscopic 

 mechanical action and the changes in current flow stimulate the nerve. In 

 either case, it is a 'trigger action.' 



This hypothesis is based on electrical phenomena that occur in the cochlea. 

 Some counterparts of these phenomena have been described for other sensitive 

 mechano-receptors, notably the non-auditory labyrinth and the lateral line 

 organs. We do not claim that the hypothesis necessarily applies to all mechano- 

 receptors. It may be unnecessary for those where plenty of energy is available 

 in the original stimulus. The electrical trigger action that we suggest may be a 

 specialization that makes possible the extreme sensitivity of the inner ear. Also 

 there is no doubt that the hypothesis as outlined is oversimplified. Further 

 experiments continue to reveal additional complexities in the action of all of 

 these sense organs; but perhaps some parts of the framework of the mechanism 

 here suggested will survive the test of time. 



REFERENCES 



1. VON Bekesy, G. DC potentials and energy balance of the cochlear partition. J. AcousL 

 Soc. Amer. 23: 576-582, 1951. 



2. VON Bekesy, G. DC resting potentials inside the cochlear partition. /. aconst. Soc. Amer. 

 24: 72-76, 1952. 



3. VON Bekesy, G. Description of some mechanical properties of the organ of Corti. /. 

 acoiist. Soc. Amer. 25: 770-785, 1953. 



4. VON Bekesy, G. and W. A. Rosenblith. The mechanical properties of the ear. In: 

 Handbook of Experimental Psychologv, edited by S. S. Stevens. New York: Wiley, 1951, 

 Ch. 27. 



5. Davis, H. Psjxhophysiology of hearing and deafness. In: Handbook of Experimental 

 Psychology, edited by S. S. Stevens. New York: Wiley, 195 1, Ch. 28. 



6. Davis, H. Energy into nerve impulses: hearing. Med. Bull. St. Louis Univ. 3: 43-48, 

 1953- 



7. Davis, H. Mechanism of hearing. In: Transactions of the Fourth Conference on the Nerve 

 Impulse. New York: Macy, 1954. 



8. Davis, H. The biophysics and neuroi)hysiology of the inner ear. Physiol. Rev. In press. 



9. Davis, H., I. Tasaki and R. Goldstein. The peripheral origin of activity, with reference 

 to the ear. Cold Spring Harbor Symp. Quant. Biol. 18: 143-154, 1952. 



10. Smith, Catherine A. Electron microscopic studies of the organ of Corti. Anat. Rec. 

 121:451, 1955. 



11. Tasaki, I., H. Davis and D. H. Eldredge. Exploration of cochlear potentials in guinea 

 pig with a microelectrode. /. Acoust. Soc. Amer. 26: 765-773, 1954. 



