96 NERVOUS SYSTEM. 



or that it is, in every part, a generator of nervous influence, so that 

 if its connexion with the brain or any other viscus be destroyed, the 

 divided portions may still possess the power of generating nervous 

 agency. But if we admit this as regards the system of the great sym- 

 pathetic, we shall find, that it is difficult to extend it to detached por- 

 tions of the nervous system of animal life. 



It must be confessed, that our knowledge of the uses of this great 

 division of the nervous system is far from being precise; for whilst 

 some physiologists believe it to be concerned in every involuntary and 

 organic action; Dr. Proctor 1 thinks, that the nearest approach to a 

 positive determination of its use that we can arrive at with our present 

 limited knowledge is, that "it is for the purpose of regulating the tonic 

 contraction of the arterial system, and for nothing else." One distin- 

 guished observer, M. Magendie, 2 inquires whether we have sufficient 

 reason for the belief, that it is a nerve at all ! and a writer 3 of distinc- 

 tion, Dr. J. C. B. Williams, admits, that nothing is definitely known 

 as to the properties communicated by ganglionic nerves; and he adds, 

 "Before the influence of the ganglionic system can be employed as an 

 element in pathology, its existence must be proved, and its properties 

 defined in physiology: this has not been done." 



According to the experiments of M. Flourens, 4 the semilunar is the 

 only ganglion that exhibits any great sensibility ; and hence it has been 

 considered as a sort of intervention to connect the viscera with the 

 encephalon. 



M. Lepelletier 5 thinks we are justified in dividing the nerves into five 

 classes: the first, comprising the nerves of special sensibility, the 

 olfactory, optic, lingual branch of the fifth pair, and auditory: the 

 second, the nerves of general sensibility, the fifth pair; and the spinal 

 nerves, through their posterior root: the third, comprising the volun- 

 tary motors; the spinal nerves, by their anterior roots, the motores 

 oculorum or common oculo-muscular, the external oculo-muscular, and 

 the hypoglossal: the fourth, instinctive motors, involuntary, respira- 

 tory nerves of Sir Charles Bell, the pathetic, facial, glosso-pharyngeal, 

 pneumogastric, and spinal accessory; and the fifth, nerves of vital 

 association and nutrition the filaments and plexuses of the ganglionic 

 system. Dr. Fletcher 6 adopts a different arrangement. He divides 

 them into ganglionic and c erebro- spinal ; the latter being subdivided 

 into the respiratory, motiferous, sensiferous, and regular; the last in- 

 cluding those which communicate both the faculty of sensibility and 

 the stimulus of volition. 



1 Medico-Chirurg. Rev., Jan., 1S45, p. 182. 



3 Precis de Physiologic, 2de edit, i. 171. Paris, 1825. 



3 Principles of Medicine, 3d Amer. edit, by Dr. Clymer, p. 200, note, Philad., 1848. 



4 Recherches Experimentales sur les Proprietes et les Fonctions du Systeme Nerveux,&c., 

 2d edit, p. 229, Paris, 1842. 



e Traite de Physiologic Medicale et Philosophique, iii. 250, Paris, 1832. 

 6 Rudiments of Physiology, P. ii. a. p. 71, Edinb., 1836. 



