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We have dwelt at some length on this subject, because we fancy- 

 that a close investigation of cases at the bed-side, with subsequent 

 pathological scrutiny, can alone set at rest this question. Although we 

 admit that Dr. Brown-Sequard deals with it, as with all the topics 

 treated of in his Lectures, with great subtlety, acuteness, and ability, 

 yet we cannot at present accept as proved, his idea that the nerve 

 fibres employed in the transmissions of sensitive impressions of touch, 

 tickling, pain, fyc. are as distinct, one from the other, as they all are 

 from the nerve fibres employed in the transmission of the orders of 

 the will to the muscles. Just as we must require of phrenologists to 

 determine psychologically what are, or what are not, the fundamental 

 faculties of the mind, before, as physiologists, we can venture to assign 

 to each its local habitation, so, before we can assign different conduc- 

 tors to each variety of sensitive impression, must we determine what 

 are the various sensitive impressions which are fundamentally distinct 

 from one another. "We may incline to admit the general truth of 

 Dr. Brown- Sequard's view with reference, for instance, to the apprecia- 

 tion of weight through muscular action, as distinct from the feeling of 

 heat, while we regard touch, tickling, ordinary pain, as mere phases of 

 one more general sensation, depending perhaps in their varieties upon 

 the texture of the skin, the hair, &c. It is certain, however, that the 

 analysis of cases given by Dr. Brown-Sequard lends considerable 

 weight to his idea : 



Thus, case 24 is reported as having lost the feeling of pinching, 

 pricking and muscular sensibility; sensibility to cold and tickling 

 remaining. 



Case 23, loss of the feeling of tickling or contact ; persistence of 

 the feeling of pain. 



Case 13, loss of tactile sensibility ; increased sensibility to painful 

 impressions. 



Dr. Budd's case, {Medico-Chiriirgical Transactions), in which 

 contact was felt while heat was not perceived. 



Ollivier's case : loss of feeling of pain on pinching ; diminished sen- 

 sibility to cold, heat, and touch. 



It has been ingeniously suggested that the appreciation of harmonic 

 sounds by the auditory nerve, the peculiar and agreeable thrill, for 

 instance, produced by notes which are the octaves of each other, bears 

 the same relation to ordinary hearing, that tickling does to ordinary 

 tactile sensibility : the notion of Dr. Brown- Sequard seems to lead to 

 the supposition that distinct nerve fibres may exist for each variety 

 of auditory sensation ; and analogy might lead to the supposition that 

 the optic nerve contained distinct conductors for every colour of the 

 spectrum, so that colour-blindness and absence of " ear" would find 

 their explanation in deficiency or absence of the conductors of these 

 sensitive impressions ; these speculations, however, touch on subjects 

 of so delicate a nature, that we fear they are likely to remain for ever 

 merely hypothetical. 



Although, therefore, it appears to us that Dr. Brown- Sequard's 



