432 NERVOUS SYSTEM. 



and attributed the elevation of temperature directly to an 

 increase in the supply of blood to the parts affected. He 

 made a most important advance in the history of the sympa- 

 thetic, by demonstrating that its section paralyzed the mus- 

 cular walls of the arteries, and, farther, that galvanization 

 of the nerve in the neck caused the vessels to contract. This 

 was the discovery of the vaso-motor nerves, concerning which 

 so much has been written within the past few years, and 

 it belongs without question to Brown-Sequard, who published 

 his observations in August, 1852. 1 A few months later, in 

 the same year, Bernard made analogous experiments, and 

 presented the same explanation of the phenomena observed. 3 



The above embraces all that is important with regard to 

 the history of experimental observations upon the sympa- 

 thetic. It is evident that we could know nothing of the 

 functions of this system before the time of Pourfour du 

 Petit, when the prevailing opinion was that the nerve origi- 

 nated from the encephalon, and that its influence was propa- 

 gated downward; and the writings of Bichat, Brachet, Tie- 

 demann, and others, published anterior to the experiments 

 of Bernard and of Brown-Sequard, present interesting sug- 

 gestions and theories, but contain little that bears upon our 

 positive knowledge. 



The important points developed by the first experiments 

 of Bernard and of Brown-Sequard were, that the sympathetic 

 influences the general process of nutrition, and that many 

 of its filaments are distributed to the muscular coat of the 

 blood-vessels. Before these experiments, it had been shown 

 that filaments from this system influenced the contractions 



1 BROWN-SEQUARD, Experimental Researches applied to Physiology and Pathol- 

 ogy. The Medical Examiner, Philadelphia, August, 1852, New Series, vol. viii., 

 p. 489. In 1839, Valentin referred to filaments of the sympathetic distributed 

 to the blood-vessels and influencing their calibre {VALENTIN, De Functionibus 

 Nervorum Cerebralium et Nervi Sympathetici, Bernae, 1839, p. 153, et seq.). 



2 BERNARD, Sur les cffets de la section de la portion cephalique du grand sinn- 

 pathique. Compte rendu des seances de la societe de biologic pendant le mois de 

 novembre, Paris, 1852, tome iv., p. 169. 



