THE NERVOUS SYSTEM. 467 



section. Varolius endeavoured to unravel it, and 

 was followed by Willis. Vicq d'Azyr, in modern 

 times, has carried the method of section to greater 

 perfection than had before been given it 5 ; as Vieus- 

 sens and Gall have done with respect to the method 

 of Varolius and Willis. Recently, Professor Chaus- 

 sier 6 makes three kinds of nerves : the encephalic, 

 which proceed from the head, and are twelve on 

 each side ; the rachidian, which proceed from the 

 spinal marrow, and are thirty on each side; and 

 compound nerves, among which is the great sympa- 

 thetic nerve. 



One of the most important steps ever made 

 in our knowledge of the nerves is, the distinction 

 which Bichat is supposed to have established, of a 

 ganglionic system, and a cerebral system. And we 

 may add, to the discoveries in nervous anatomy, 

 the remarkable one, made in our own time, that the 

 two offices of conducting the motive impressions 

 from the central seat of the will to the muscles, and 

 of propagating sensations from the surface of the 

 body and the external organs of sense to the sen- 

 tient mind, reside in two distinct portions of the 

 nervous substance: a discovery which has been 

 declared 7 to be "doubtless the most important 

 accession to physiological (anatomical) knowledge 

 since the time of Harvey." This doctrine was first 

 published and taught by Sir Charles Bell : after an 



6 Cuv. p. 40. Diet. Sc. Nat. xxxv. 467- 



7 Dr. Charles Henry's Report of Brit. Assoc. iii. p. 62. 



HH2 



