104 



HABIT AND INTELLIGENCE. 



[chap. 



fecliiig 

 than 

 visual 

 beauty, 

 because 

 the ear 

 loses 110 

 time in 

 conibiiiii 

 impres- 

 sions. 



of this pi'obal)ly is, that the beauty, or what is called by 

 au expression which is scarcely a metaphor, the harmony, 

 of form and colour is due to the combination of several 

 distinct impressions on the sense of sight, which cannot 

 be properly combined without a motion of the eye ; and 

 this occupies some little time ; while the harmony of sound 

 i.s due to the combination of distinct impressions on the 

 sense of hearino- which combine in the consciousness of 

 themselves, without any time being lost. To this fact, 

 that no time whatever is lost in combining simultaneous 

 impressions of sound, while some little time is lost in 

 combining simultaneous impressions of sight, I attribute 

 the ]:)eculiarly \ivid and intense effect of music on the 

 consciousness. 



XOTE A. 



NERVES OF SPECIAL SENSATION, 



Opinion of 

 distinct 

 nerves for 

 distinct 

 colours. 



Reasons 



aj^ciiust 



this. 



No special 

 nerves of 

 taste. 



The ojjiniou was first advanced by Dr. Youug, and has lately 

 been sanctioned by the high authority of Helmholtz,^ that there 

 must be three distinct sets of nerve-fibres in the retina and the 

 optic nerve, one for each of the three primary coloui'S. On this 

 subject it is difficidt to see how there can ever be any absolutely 

 conclusive evidence ; for, supposing the three sets of nerves to 

 exist, and to be distinctly visible under the microscope, how 

 could the distinct function of each be ascertained 1 But there 

 are what appear to me the strongest analogical reasons for reject- 

 ing such an hypothesis. 



The hypothesis in question rests on the belief that each sen- 

 sory nerve must transmit a single kind of sensation, and cannot 

 trausniit any other. Now this belief appears to be contrary to 

 such evidence as we can obtahi. Dr. Carpenter says of the 

 sense of taste : " There is no special nerve of taste ; for the 

 gustative impressions upon the front of t)ie tongue are conveyed 

 (to the sensory ganglia) by the Lingual branch of the fifth pair, 

 while those made upon the back of the organ are conveyed by 

 the Glosso-pharyngeal, both of which nerves also minister to 

 common sensibility (or the sense of touch) ; and pressure on the 

 1 Physiological Theory of Musie, French fvanslatiou, p. 185. 



