OCTOBER 223 



partridge or the chirp of a cicala. Some persons have 

 naturally what is termed ' an ear for music ' ; in others 

 the response to musical notes is less developed. The 

 degree of perception depends upon the sensitiveness 

 of an apparatus of extraordinary complexity situated 

 within the cochlea of the ear. This apparatus, known 

 as the organs of Corti (being named after Count Corti, 

 who discovered it), consists, roughly speaking, of 

 between three and four thousand tense fibres, ranged 

 in serried rows, and bent so as to form bows or arches. 

 This apparatus is susceptible of training to a very high 

 degree of delicate perception. Weber calculated that 

 a sensitive ear may be educated so as to be capable of 

 distinguishing the difference of ^th of a tone ; giving 

 nearly four thousand distinct sounds, corresponding 

 pretty closely, perhaps precisely, with the number of 

 arched fibres in the organs of Corti. But these fibres, 

 according to Helmholtz, do not respond to any note 

 outside the seven octaves comprised in human music. 

 Nobody who has given any thought to the problem 

 would be so rash as to maintain that the hearing 

 apparatus of every kind of animal is attuned to the 

 same range of vibrations and its sense of hearing 

 subject to the same limitations as that of man. To 

 take examples from low down in the scale of animals, 

 the hearing organs of Medusse or jellyfish and lobsters 

 must be attuned to a vastly different kind of sound 

 from those of terrestrial creatures. We cannot even 

 imagine what class of sound can take place under the 

 sea, though one can understand that ifc is important for 

 such vulnerable creatures to be able to recognise the 



