THE SYMPATHETIC SYSTEM. 591 



they recommence and again increase in intensity so soon as the gal- 

 vanization of the nerve is suspended. 



The same author has shown that a similar influence is exerted by the 

 sympathetic nerve upon the circulation in the limbs. 1 If the lumbar 

 nerves of one side be divided, in the dog, within the cavity of the spinal 

 canal, paralysis of motion and sensibility is produced in the correspond- 

 ing limb, but there is no change in its vascularity or temperature ; while 

 if the lumbar portion of the sympathetic be divided or excised, without 

 disturbing the spinal nerves, all the signs of increased temperature and 

 activity of the circulation are manifested in the limb below, without loss 

 of motion or sensibility. Exsection of the first thoracic ganglion of the 

 sympathetic produces similar effects in the anterior extremity ; and 

 these effects are diminished or suspended by electric irritation of the 

 divided nerve. 



Division of the sympathetic nerve, accordingly, produces dilatation 

 of the bloodvessels and consequent increased rapidity of the circula- 

 tion, and causes the blood to retain its red color in the veins ; while gal- 

 vanization of the same nerve produces contraction of the vessels, dimin- 

 ishes the quantity of the circulating fluid, and causes the change in 

 color of the blood, from arterial to venous. 



The same thing takes place in the glandular organs. If the submax- 

 illary or parotid gland be exposed in the living animal, 2 so long as the 

 gland is in its ordinary condition the blood passing through it is seen 

 to undergo the usual changes, and returns dark colored by the veins. 

 But if the sympathetic filament which accompanies the external carotid 

 artery be divided, the quantity of blood flowing through the gland is at 

 once increased, and appears of a red color in the veins. The same 

 changes occur when the gland is excited to secretion by stimulating 

 the organs of taste. 



An apparent antagonism exists, in regard to the circulation, between 

 the sympathetic nerve and those derived from the cerebro-spinal 

 system. If the chorda tympani, which sends filaments to the submax- 

 illary ganglion, be galvanized, it causes an excitement of the secretion 3 

 in the submaxillary gland, increased activity of the circulation, and a 

 red color of the blood in the veins. The division of this nerve is followed 

 by a contrary result. The effects produced, therefore, by galvanization 

 of the chorda tympani are those produced by division of the sympa- 

 thetic ; and the effects produced by galvanizing the sympathetic are 

 those which follow division of the chorda tympani. 



The vascularity of the parts, accordingly, as well as the glandular 

 activity of vascular organs, are under the control of the nervous system. 

 The filaments of the sympathetic nerve accompany everywhere the blood- 

 vessels, enveloping the arterial branches with an abundant plexus, and 



1 Journal de la Physiologic de PHomme et des Animaux. Paris, 1862, p. 397. 



2 Bernard, Legons sur les Liquides de I'Organisme. Paris, 1859, tome i. p. 230. 

 9 LeQons sur les Liquides de 1'Organisme. Paris, 1859, tome i. p. 312. 



