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XII. Of the Third Pair of Nerves, being the first of a series qfjwpers in explanation of 

 the difference in the origins of the Nerves of the Encephalon, as compared with those 

 which arise from the Spinal Marrow. By Sir Charles Bell, K. H., F. R. SS. 

 L. Sf Ed., M. D. H. Gott., <§c. 



(Read 2d AptU 1838.) 



It is not a little remarkable, that in an age which assumes to itself the cha- 

 racter of devotion to science, in anatomy, a science which embraces the best inte- 

 rests of humanity, this question should remain unanswered ; What is the mean- 

 ing of the nerves of the spinal marrow being in regular order and perfectly sym- 

 metrical : whilst tlie ten nerves arising from the brain present no similarity ons to 

 another, and agree neither in oi'igin, size, nor distribution ? 



It is plain that we must be in the dark, not only with respect to the know- 

 ledge of the nervous system, but of the animal frame generally, whilst such a 

 question is open and courts inquiry, and yet remains without an effort being 

 made towards its solution. We must, I fear, attribute this neglect in part only to 

 the difficulty of the inquiry, and much to the indifference to all that does not 

 tend directly to profit ; on which account it has the better demand on the atten- 

 tion of a learned and philosophical Society. 



So far back as the year 1811, I ventured to announce this principle, that in 

 the nervous system a filament possessed the same endowment, performed the same 

 ftmction through its whole course, whether that filament be in a nerve, or traced from 

 the nerve into the sjnnal marrow, or from the sjnnal marrow into the brain. 



The truth of this is apparent as soon as expressed, and inquiries directed on 

 this principle have given it countenance and importance. It enabled me to shew 

 that what was called a common nerve, being such as was supposed to possess all 

 the vital properties, consisted of two nerves joined in the same sheath — one pre- 

 siding over motion, and the other the seat or organ of sensation. Following out 

 the principle, I found that the roots of the so-caUed " common" nerves differing 

 in function, arose from distinct columns of the spinal man-ow, and that these co- 

 lumns coiTesponded with the roots of the nerves to which they gave origin. That 

 is to say, that the anterior of these columns presided over motion, and the other 

 over sensation : That they were distinct, but not separated in their course, and 

 preserved their parallelism and resemblance even till lost in the cerebrum. For 

 at the point where the anterior columns join, and decussate in the medulla 



