MECHANICS OF THE INNER EAR 33 



is theoretically almost beyond our reach. We cannot, in the 

 present state of our knowledge, obtain a very clear idea of 

 differences in the suddenness with which the nerve ends 

 might be shaken in different cases. It will be best, therefore, 

 to omit this factor in the discussion of intensity altogether, 

 or at least for the present, rather than burden our theory 

 with arbitrary hypotheses the usefulness of which is no more 

 probable than their uselessness. At present we shall limit 

 our discussion to the first condition, the number of those nerve 

 ends which are stimulated with equal frequency. 



It is clear that the number of nerve ends stimulated de- 

 pends in some way on the length of that part of the partition 

 which is jerked up and down in a certain 

 . frequency. But here we are confronted by 



... .. *■ , this difficulty. We do not know whether 



the theoretical J 



determination of tne nerve fibres are equally distributed 

 tone intensity. along the partition. It might be the case 



Fifth provisional that on a certain length of the partition 

 assumption near the windows a greater number of 



nerve ends were found than on an equal 

 length farther away from the windows ; or the reverse. In 

 our present state of knowledge this difficulty cannot be over- 

 come. In order to go on with our theory, we have to make 

 an assumption. We shall make, of course, the simplest, the 

 least arbitrary assumption. We assume, provisionally, that 

 equal parts of the partition lengthwise contain equal num- 

 bers of nerve ends. If it should be found that the theory 

 agrees with the facts of auditory observation more closely un- 

 der another assumption, we would have to substitute this for 

 the one now made. Of course a definite answer given to the 

 problem by the anatomists would be more satisfactory. 



