350 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



points in the organ of Corti corresponding to those tones, 

 and not for the tones themselves : the question of inter- 

 ference between them does not therefore arise. 



To which of these results the disagreeable and "restless " 

 effect of a discord is due cannot be said with certainty, 

 but it is probable the following all contribute to the 

 restlessness : 



(1) The rhythmic variation of intensity of primary 

 stimuli beyond ordinary limits : 



(2) The rapid succession of faint but unequal stimuli in 

 very widely separated regions of the organ, each stimulus 

 being due, in most cases, to two waves only and, hence, 

 giving rise to a comparatively ill-defined sensation : 



(3) The probable stimulation of the whole area between 

 c' and d'. 



With intervals less simple than this 8 : 9 discord the 

 beat-period becomes longer and the beats more distinct. 

 The " beat " itself is the rhythmically recurring augmen- 

 tation of the primary stimuli : and their disagreeable effect 

 is avoided in rapid music where the successive chords are 

 not sustained long enough to produce this effect. 



It would seem to be inadvisable now to enter into 

 questions of more complex combinations of tones either 

 harmonious or discordant — apart even from limits of space. 

 The examples already given are sufficient to exemplify 

 the principles I have laid down. 



An objection has been raised, first by myself and then 

 by almost everybody who has been led to discuss the 

 theory with me. 



According to the theory now set forth, the region of the 

 cochlea where the stimulation by high tones occurs is 

 near the apex ; low ones producing a stimulation near 

 the base. 



Older theories based on assumptions of " resonance " of 



