60 THE GENESIS OF SPECIES. [CHAP. 



historical time began. And it is to be further observed, 

 that no improvement will give its possessor a certainty of 

 surviving and leaving offspring, but only an extra chance, 

 the value of which it is quite impossible to estimate." 

 This difficulty is, as Mr. Murphy points out, greatly inten- 

 sified by the undoubted fact that the wonderfully complex 

 structure has been arrived at quite independently in beasts 

 on the one hand and in cuttle-fishes on the other ; while 

 creatures of the insect and crab division present us with a 

 third and quite separately developed complexity. 



As to the ear, it would take up too much space to 

 describe its internal structure ; x it must suffice to say, that 

 in its interior there is a series of minute rod-like bodies, 

 termed fibres of Corti, having the appearance of a key- 

 board, and each fibre being connected with a filament of 

 the auditory nerve : these filaments being like strings to 

 be struck by the keys, i.e. by the fibres of Corti. Moreover, 

 this apparatus has been supposed to be a key-board in 

 function as well as in appearance, the vibration of each 

 one fibre giving rise, as some believe, to the sensation of 

 one particular tone, and combinations of such vibrations 

 producing chords. It is by the action of this complex 

 organ, if not by some yet undiscovered auditory structure, 

 that all the wonderful intricacy and charm of Beethoven 

 and Mozart come to be perceived and appreciated. 



Now it can hardly be contended that the preservation of 

 any race of men in the struggle for life ever depended on 

 such an extreme delicacy and refinement of the internal 

 ear> a perfection only exercised in the enjoyment and 

 appreciation of the most exquisite musical performances. 



1 The reader may consult Huxley's "Lessons in Elementary Physi- 

 ology," p. 204. 



