HEARING 417 



simply in order that we may escape from physiological em- 

 barrassments. 



The organ of Corti has in the highest degree the appearance 

 of a piece of apparatus for the analysis of sound. If the 

 basilar membrane, with the cells which rest upon it, be cut 

 out and laid flat, the suggestion of some kind of instrument is 

 very strong. It is a long narrow ribbon, narrowest at the 

 bottom of the spiral, increasing to about twice the width at 

 the apex. It is crossed by radiating fibres, presumably 

 elastic. The cells which rest upon it carry vibrating hairs, 

 and are supplied with nerves. The rods of Corti hold up the 

 reticulated membrane, which keeps the hair-cells in place. It 

 is not to be wondered at that when its structure was first 

 discovered it was thought that the problem of the analysis 

 of musical tones was solved. If two pianos in perfect tune are 

 in the same room, when one is played the corresponding 

 wires of the other twang. Anyone who sings into a piano, 

 whilst the loud pedal raises the dampers, feels an increased 

 fulness in his voice. This is the familiar phenomenon of 

 resonance. Why should not the fibres of the basilar membrane 

 resonate to the tones conveyed to the ear the shorter ones at 

 the base of the cochlea to high tones, the longer ones at the apex 

 to low tones ? This is the order in which we should expect the 

 pulsations of sound which ascend the scala vestibuli to be 

 taken up the more rapid near its commencement, the less 

 rapid farther up it. But an explanation of the physics of the 

 selection of vibrations of different frequencies by different sets 

 of the elements which make up the organ of Corti, if such selec- 

 tion occurs, is still to seek. In the first place, the fibres of the 

 basilar membrane are so exceedingly short. What could a fibre 

 less than 0-5 millimetre in length make of the vibrations of 

 a 36-foot organ-pipe ? Even if this objection be waived, as 

 certain eminent physicists hold that it may be, there is not a 

 sufficient difference in length between the longest and the 

 shortest fibres to account for the great range of tones which 

 we are able to discriminate ; nor is there any evidence that 

 some fibres are more tightly stretched than others. 



A further consideration which tempts physiologists to look 

 upon the organ of Corti (including the basilar membrane) as 

 a series of resonators is the somewhat rema/rkable agreement 



27 



