XXIX.] THE PHYSIOLOGY OF MIND. 25 



hemispliere, are connected with each other by other 

 masses of fibres. 



Concerning the functions of these various parts, we have The 

 no direct evidence whatever. We have no guide but ontsTarts 

 analogy. With the help of analogy, however, I believe can be 



tiscGr- 



that a tolerably complete and satisfactory theory can be tained 

 formed. I ought first to mention, that the theory of the so- °^^y '^^ 



" '' analogy. 



called phrenologists is not only unproved, but disproved, 

 by facts.^ According to that theory, the cerebral hemi- Phreno- 

 spheres consist of a congeries of organs, in each of which a ^^^y 

 distinct mental function is localized — comparison, imagina- disproved 

 tion, firmness, love of children, &c. Were this true, in- 

 juries to the brain would injure the mind in definite ways, 

 according to the locality of the injury. But this is not the 

 case ; injuries to the brain, when the patient recovers at 

 all, appear generally to leave the mind unaffected, even 

 when a part of the substance of the brain has been lost ; 

 and they certainly do not affect the mind in any way that 

 can be predicted when the seat of the injury, and its mag- 

 nitude, are known. Experiments on animals yield the 

 same result. 



We have seen that it is in accordance with the analogies One 

 of the nervous system, that a current along one nerve-fibre current 

 should determine a current to be sent along another fibre. ^ producing 

 Thus, for instance, if the impression of a flash of light is 

 telegraphed along the optic nerve to the sensory ganglia, a 

 motor impulse is telegraphed along another nerve, causing 

 the eyelids to close. I think it most probable that the 

 nervous mechanism of consciousness resembles this. It is 

 ■ certain that sensation is produced by the flow of a current 

 of nervous energy along a nerve-fibre of sense to its 

 ganglion ; the sensation of light, for instance, is produced 

 by a current flowing along the optic nerve to the optic 

 ganglia. Let us call this the nerve-current of sensation. 

 Now, if consciousness is a feeling, which it certainly is ; 



1 I think there is verj' probably, however, this much truth in phreno- 

 logy, that there is a tolerably close correlation between the form of the 

 brain (which determines the form of the skull) and the mental character. 



^ See Note at end of chapter, 



