CHAP, xxx.] BERNARD'S RESEARCHES. 429 



of the nervous centres are accompanied with a diminution of 

 temperature, and of the power of forming heat. Again, the tem- 

 perature of paralyzed limbs is almost always less than that of sound 

 limbs, and often so to a very marked degree. In some instances, 

 however, twin lesions of the nervous system are followed by an 

 opposite effect. Much light has been thrown upon the influence of 

 the nervous system upon the development of heat, by the recent 

 highly interesting and important researches of M. Bernard. 



Bernard has lately established the very interesting fact, that 

 section of the sympathetic nerve is followed by a considerable 

 elevation of temperature in that side of the head or face corre- 

 sponding to the divided trunk. This increase of temperature 

 occurs immediately; and persists after all increased vascularity 

 and turgescence have disappeared, and after the wound in the neck 

 has quite healed. The same observer found that sections of nerves 

 of motion and sensation produce respectively, besides paralysis, a 

 diminution of temperature, while, if a mixed nerve containing 

 fibres of the sympathetic, as the facial, is divided, an exaltation 

 of temperature takes place, arising, doubtless, from the division of 

 the sympathetic fibres. The increase of temperature seems to be 

 a special result of the division of the sympathetic. 



Now, if the upper extremity of the sympathetic, which has been 

 divided in the neck of an animal, be subjected to an interrupted 

 galvanic current, the exalted temperature which follows its division 

 is no longer manifested, and the parts supplied by it actually fall 

 below the normal standard, and they rise again when the current 

 is stopped. When an animal, in which the sympathetic had been 

 divided, was placed under the influence of chloroform, the tem- 

 perature which had risen several degrees in consequence of the 

 division of the nerve, fell, while it again rose when the animal had 

 recovered from the effects of the chloroform. 



Bernard has shown that the increased temperature following- 

 division of the sympathetic, or removal of the superior cervical 

 ganglion, cannot be attributed solely to the increased quantity of 

 blood which is allowed to enter the vessels in consequence of 

 paralysis of their contractile coats ; for it occurs when the blood is 

 allowed to stagnate in the vessels by tying them. At the same 

 time, it is necessary that the vessels should contain blood. The 

 enlargement of the vessels and the increased flow of blood to the 

 parts are to be looked upon as the result of the altered nutritive 

 changes which take place in consequence of the division of the 

 sympathetic, rather than as the cause of the rise of temperature. 



