FUNCTIONS OF THE SYMPATHETIC SYSTEM. 433 



of the muscular coats of the alimentary canal. Leaving, for 

 the present, the action of the vaso-motor nerves, we will 

 briefly recapitulate some of the facts with regard to the in- 

 fluence of the sympathetic upon animal heat and secretion. 



AVhen the sympathetic is divided in the neck, the local 

 increase in temperature is always attended with a very great 

 increase in the supply of blood to the side of the head corre- 

 sponding to the section. The increased temperature is due 

 to a local exaggeration of the nutritive processes, apparently 

 dependent directly upon the hypersemia ; and it is not prob- 

 able that there are any nerves to which the n^me of calorific, 

 as distinguished from yaso-motor, can justly be applied. 

 There are numerous instances in pathology of local increase 

 in temperature attending increased supply of blood to re- 

 stricted parts. 



The experiment of dividing the sympathetic in the neck, 

 especially in rabbits, is so easily performed, that the phenom- 

 ena observed by Bernard and Brown- Sequard have been re- 

 peatedly verified. We have often done this in class-demon- 

 strations. A very striking experiment is the following, sug- 

 gested by Bernard : 1 After dividing the sympathetic arid ex- 

 hibiting the increase in the temperature and the vascularity 

 of the ear on one side in the rabbit, if both ears be cut off 

 just above the head with a sharp knife, the artery on the 

 side on which the sympathetic has been divided will fre- 

 quently send up a jet of blood to the height of several feet, 

 while, on the sound side, the jet is always much less forcible, 

 and may not be observed at all. This experiment succeeds 

 best in large rabbits. 



It is very easy to observe the effects of dividing the 

 sympathetic in the neck, but analogous phenomena have been 

 npted in other parts. Among the most striking of these 

 experiments are those reported by Samuel, who noted an 

 intense hyperaemia of the mucous membrane of the stomach 



1 BERNARD, Rechcrches experimentales sur les nerfs vascidaires et calorifiqucs 

 du grand sympathique. Journal de la physiologic, Paris, 1862, tome v., p. 397. 



