416 inTTRITION. 



functions of the sympathetic system and its relations to nu- 

 trition. In this connection, we will simply allude to certain 

 phenomena manifested through the nervous system, without 

 attempting to fully explain their mechanism. 



It is well known that when the sympathetic nerves going 

 to a particular part are divided, the arterial coats are para- 

 lyzed and dilated, the supply of blood is increased, nutrition 

 is locally exaggerated and more or less modified, and the 

 temperature of that particular part is increased by from five 

 to ten degrees. An illustration of these facts in the ear of 

 the rabbit, after division of the sympathetic in the neck, is a 

 very common observation, which we have often verified in 

 public demonstrations. All of these unnatural phenomena 

 disappear on galvanizing the divided extremity of the nerve. 

 These local modifications in the temperature have been fre- 

 quently observed pathologically in the human subject. 



A number of curious local variations of temperature can 

 be explained by direct or reflex action through the sympa- 

 thetic nerves. Brown-Sequard and Lombard observed that 

 pinching of the skin was soon followed by an elevation in 

 temperature, and was attended also with a diminution in the 

 temperature in the corresponding member on the opposite 

 side. Sometimes the irritation of the upper extremities pro- 

 duced changes in temperature in the lower limbs. 1 Exam- 

 ples of reflex action through the sympathetic nerves are 

 given by Tholozan and Brown-Sequard, in a very interest- 

 ing series of experiments. These physiologists found that 

 lowering the temperature of one hand produced a considera- 

 ble diminution in the temperature of the other hand, without 

 any great depression in the general heat of the body ; and 

 Brown-Sequard showed that by immersing one foot in water 

 at 41, the temperature of the other foot was diminished 

 about 7 in the course of eight minutes. 2 



1 BROWN-SEQUARD ET LOMBARD, Experiences sur F influence de V irritation des 

 nerfs de la peau sur la temperature des membres. Archives de physiologic, Paris, 

 1868, tome i., p. 691. 



8 THOLOZAN ET BROWN-SEQUARD, Recherche* experimentales sur quelqu'uns des 



