HERMANN VON HELMHOLTZ 



complexity in the structure of all the terminal organs 

 of special sense, as if there arose a necessity for 

 differentiation and discrimination in the effects of 

 various kinds of stimuli ; and (3) investigations into 

 the action of all the sense organs, such as those of 

 touch and temperature in the skin, of light and colour 

 in the retina, of taste in the tongue, and of smell in 

 the olfactory region, all indicate specialization of 

 function in the peripheral apparatus. 



Although the conception that vibrators exist in 

 the cochlea flitted before the minds of Thomas 

 Young, John and Charles Bell, and Johannes Miiller, 

 it was first clearly put forward by Helmholtz. It 

 may be shortly stated as follows : (i) In the cochlea 

 there are vibrators, tuned to frequencies within the 

 limits of hearing, say from 30 to 40,000 or 50,000 vibra- 

 tions per second ; (2) each vibrator is capable of exciting 

 its appropriate nerve filament or filaments, so that a 

 nervous impulse, corresponding to the frequency of 

 the vibrator, is transmitted to the brain, not corre- 

 sponding necessarily as regards the number of nervous 

 impulses, but in such a way that when the impulses 

 along a particular nerve fibre reach the brain, a state of 

 consciousness is aroused which does correspond with 

 the number of the physical stimuli, and with the 

 period of the auditory vibrator ; (3) the mass of each 

 vibrator is such that it will be easily set in motion, 

 and after the stimulus has ceased it will readily come 

 to rest ; (4) damping arrangements exist in the ear, 

 152 



