and Nervous Filaments into Motive and Sensitive, 69 



ganism to the enveloped substance of the brain, the after-brain, the 

 spinal chord and nerves. But as the animal faculty is one, and its 

 proximate vehicle, the animal spirits, is homogeneous, so the nervous or 

 cerebral substance which conducts these spirits is in its own nature 

 uniform, and indifferently competent to either function ; it being de- 

 pendent upon tuo accidental circumstances, whether this substance con- 

 duce to motion, to sensation, or to motion and sensation together. 



The first circumstance is the degree of hardness or softness ; a nerve 

 being adapted to motion, or to sensation, in proportion as it possesses 

 the former quality or the latter. Nerves extremely soft are exclusively 

 competent to sensation. Nerves extremely hard are pre-eminently, but 

 not exclusively, adapted to motion ; for no nerve is wholly destitute of 

 the feeling of touch. The soft nerves, short and straight in their course, 

 arise from the anterior portion of the encephalos (the Brain proper ;) 

 the hard, more devious in direction, spring from the posterior portion 

 of the brain where it joins the spinal chord (Medulla oblongata?) the 

 spinal chord being a continuation of the After-brain, from which no 

 nerve immediately arises ; the hardest originate from the spinal chord 

 itself, more especially towards its inferior extremity. A nerve soft in 

 its origin, and therefore fitted only for sense, may, however, harden in 

 its progress, and by this change become suitable for motion. 



The second circumstance is the i>rtr« to which a nerve is sent; the 

 nerve being sensitive or motive as it terminates in an organ of sense, or 

 in an organ of motion — a muscle ; every part being recipient only of 

 the virtue appropriate to its special function. 



This theory of Galen is inadequate to the phsenomena. For, though 

 loss of motion without loss of sense may thus be accounted for, on 

 the supposition that the innervating force is reduced so low as not to 

 radiate the stronger influence required for movement, and yet to radiate 

 the feebler influence required for feeling, still this leaves the counter 

 case (of which, though less frequently occurring, Galen has himself 

 recorded some illustrious examples) not only unexplained, but even ren- 

 ders it inexplicable. In this theory Galen is, likewise, not always con- 

 sistent with himself. The distinction of hard and soft, as corresponding 

 with the distinction of motory and sensitive nerves, though true in 

 general, is, on his own admission, not absolutely through-going. (I 

 must observe, however, that, among other recent anatomists, this is 

 maintained by Albinus, Malacarne, and Reil.) And to say nothing of 

 other vacillations, Galen, who in one sentence, in consistency with his 

 distinction of cerebral and (mediately) cerebellar nerves, is forced to 

 accord exclusively to those of the spine the function of motion ; in 

 another finds himself compelled, in submission to the notorious fact, to 

 extend to these nerves the function of sensation likewise. But if 

 Galen's theory be inadequate to their solution, it never leads him to 

 overlook, to dissemble, or to distort, the phenomena themselves ; and 

 with these no one was ever more familiarly acquainted. So marvellous. 



