THEIR LIMITS AND THEIR FALLACIES. 313 



called acupuncture consists in thrusting sharp needles deep 

 into the flesh. In conducting this operation, very little pain 

 is felt after the needle has penetrated below the skin. 



Even the special organs of other senses are endowed with 

 common sensibility, i. e. touch ; and for that reason are sup- 

 plied with nerves other than those belonging to their own 

 respective special senses. The late Sir Charles Bell was first 

 to show, that in all nerves which have double roots, one is 

 made-up of nerve-filaments belonging to touch, or common 

 sensation ; the other, of filaments appertaining to motion. 



The spinal nerves are typical of this double-root forma- 

 tion. In every spinal nerve an anterior and a posterior root 

 are recognisable ; of these, the latter appertains to touch, or 

 common sensation. This has been proved by vivisectional 

 experiments. It was found, that if the posterior root of either 

 of the spinal nerves be cut, the common sensation of the part 

 to which it goes is utterly abolished. 



The senses are all allied; they aid and assist one ano- 

 ther ; and when one or more are abolished, then, as common 

 experience teaches, the others become acute to an extraor- 

 dinary degree. Considered as to its alliance, touch stands 

 nearest to the sense of hearing ; so near, that, in the case of 

 certain lower animals, the point is not determined whether 

 motion following a noise be the result of mere tremors, 

 surf ace - conveyed through touch or ordinary sensation or 

 whether of sound-waves, the result also of tremors, but con- 

 veyed to the auditory sensorium. 



Guided by the same evidence, physiologists are not agreed 

 as to whether the sense of hearing needs, in all cases, the 

 presence of a special auditory apparatus. The result may 

 be feeling, or it may be hearing ; the problem is indetermi- 

 nate. 



Considered as to its vicarious function, as to its power of 

 standing in aid of defective or absent sensation of different 

 qualities, the sense of vision is that to which touch is most 



