MODIFICATIONS OF SECRETION. 31 



distributed to the muscular coats of the arteries of supply. 

 When these filaments are divided, the circulation is increased 

 here, as in other situations, and secretion is the result ; and, 

 if the extremity of the nerve connected with the gland be 

 galvanized, contraction of the vessels follows, and the secre- 

 tion is arrested. 1 



With regard to many of the glands, Bernard has shown 

 that the influence of the sympathetic is antagonized by nerves 

 derived from the cerebro-spinal system, which he calls the 

 motor nerves of the glands. The motor nerve of the sub- 

 maxillary is the chorda tympani ; and as both this nerve 

 and the sympathetic, together with the excretory duct of the 

 gland, can be easily exposed and operated upon in a living 

 animal, most of the experiments of Bernard have been per- 

 formed upon this gland. When all these parts are exposed 

 and a tube introduced into the salivary duct, division of the 

 sympathetic induces secretion, with an increase in the circu- 

 lation in the gland, the blood in the vein becoming red. On 

 the other hand, division of the chorda tympani, the sympa- 

 thetic being intact, arrests secretion, and the venous blood 

 coming from the gland becomes dark. If the nerves be now 

 galvanized alternately, it will be found that galvanization 

 of the sympathetic produces contraction of the vessels of the 

 gland and arrests secretion, while the stimulus applied to 

 the chorda tympani increases the circulation and excites se- 

 cretion. 3 



These experiments show that the submaxillary gland has 

 distributed to it a special nerve which is capable of exciting 

 its functional activity, the sympathetic ramifying upon 

 the walls of the blood-vessels in this, as in other situa- 

 tions ; and it remains to see whether other glands are like- 

 wise supplied with motor nerves. In his lectures, delivered 

 in 1861, Bernard announced that he had demonstrated the 

 existence of such nerves for the other salivary glands. 



1 BERNARD, Liquides de Vorganisme, Paris, 1859, tome ii., p. 270. 

 8 Op. cit., p. 267, et seq. 



