HELMHOLTZ IN BONN 



so as to quickly extinguish movements of the vibrators ; 

 (5) if a simple tone falls on the ear, there is a pendular 

 movement of the base of the stapes, which will affect 

 all the parts, causing them to move ; but any part 

 whose natural period is nearly the same as that of the 

 sound will respond on the principle of sympathetic 

 resonance, a particular nerve filament or nerve fila- 

 ments will be strongly affected, and a sensation of a 

 tone of a definite pitch will be experienced, thus 

 accounting for the discrimination of pitch ; (6) intensity 

 or loudness will depend on the amplitude of movement 

 of the vibrating body, and consequently on the 

 intensity of nerve stimulation ; (7) if a compound 

 wave of pressure be communicated by the base of the 

 stapes, it will be resolved into its constituents by the 

 vibrators corresponding to the tones existing in it, 

 each vibrator picking out its appropriate constituent 

 and thus irritating its corresponding nerve filament, so 

 that nervous impulses are transmitted to the brain, 

 where they are fused in such a way as to give rise 

 to a sensation of a particular quality or character, but 

 still so imperfectly fused that each constituent, by a 

 strong effort of attention, may be specially recognised. 

 This last statement affords an explanation of the 

 analytic powers of the ear. 



Now the structure of the ductus cochlearis, in 



which the nerve-endings exist, meets the demands 



of this theory. It is highly differentiated, and its 



parts appear suitable for executing independent vibra- 



J 53 



