76 Historical Notices in regard to the Distinction of Nerves. 



nous mollusca, the raedusoe or sea-blubbers, which are not more remark- 

 able for their transparency than for their contractile and dilative powers. 



4. As I have already noticed, the celebrity of the Ley den School, far 

 from commanding acceptance, did not even secure adequate attention to 

 the doctrine of its illustrious masters ; and the Galenic theory, to which 

 Haller latterly adhered, was, under the authority of Cullen and the 

 Monros, that which continued to prevail in this country, until after the 

 commencement of the present century. Here another step in advance 

 was then made b}^ Mr Alexander Walker, an ingenious jihysiologist of 

 Edinburgh ; who, in 1809, first started the prolific notion, that in the spinal 

 nerves the filaments of sensation issue by the one root, the filaments of 

 motion by the other. His attribution of the several functions to the se- 

 veral roots — sensation to the anterior, motion to the posterior — with 

 strong presumption in its favour from general analogy, and its confor- 

 mity with the tenor of all previous, and much subsequent, observation, 

 is, however, opposed to the stream of later and more precise experiment. 

 Anatomists have been long agreed that the anterior column of the spinal 

 marrow is in continuity with the brain-proper, the posterior, with the 

 after-brain. To say nothing of the Galenic doctrine, Willis and the 

 School of Boerhaave had referred the automatic, Hoboken and Pouteau 

 the automatic and voluntary, motions to the cerebellum. Latterly, the 

 experiments of Rolando, Flourens, and other physiologists, would shew 

 that to the after-brain belongs the power of regulated or voluntary mo- 

 tion ; while the parallelism which I have myself detected, between the 

 relative development of that part of the encephalos in young animals and 

 their command over the action of their limbs, goes, likewise, to prove 

 that such motion is one, at least of the cerebellic functions. (See Monro's 

 Anatomy of the Brain, 1831, p. 4-9.) In contending, therefore, that 

 the nervous filaments of sensation ascend in the anterior rachitic column 

 to the brain-proper, and the nervous filaments of motion in the posterior, 

 to the after-brain, Mr Walker originally proposed, and still maintains, 

 the alternative which, independently of precise experiment, had the 

 greatest weight of general probability in its favour. (Archives of Science 

 for 1809 ; The Nervous System, 1834, p. 50, sq.) 



5. In 1811, Sir Charles Bell, holding always the connection of the 

 brain-proper with the anterior, of the after-brain with the posterior, co- 

 lumn of the spinal chord, proceeding, however, not on general proba- 

 bilities, but on experiments expressly instituted on the roots themselves 

 of the spinal nerves, first advanced the counter doctrine, that to the fila- 

 ments ascending by the posterior roots belongs exclusively the function 

 of sensation; and thereafter, but still, as is now clearly proved, previ- 

 ously to any other physiologist, he further established, by a most inge- 

 nious combination of special analogy and experiment, the correlative 

 fact, that the filaments descending by the anterior roots are the sole 

 vehicles of voluntary motion. These results, confirmed as they have 



