A STUDY OF FEVER. 15 



Having investigated the mode of origin of fever from tlie 

 clinical standpoint, as far as we are able, it is evident that we 

 must supplement this study by an experimental investigation. 

 As it has been shown that the elevation of temperature is at 

 least sometimes brought about through the agency of the ner- 

 vous system, the experimental inquiry will first be directed to 

 discovering to what extent, and in what way, the nervous 

 sj^stem does influence animal temperature. 



In 1810 P. Heidenhain announced (PJiuger^s Archiv, p. 504) 

 that when a sensitive nerve is stimulated, a fall of temi)erature 

 occurs simultaneously with the rise of the blood pressure. I 

 shall not attempt to follow this memoir closely, but shall simply 

 state the results of the experiments, the conclusions drawn, and 

 the evident reasons there are for not allowing the justice of the 

 deductions made. 



The experimental facts which were reached are as follows: — 



1st. Irritation of a sensitive nerve causes a rise in blood 

 pressure but a fall in temperature. 



2d. This fall occurs in the posterior part of the body even 

 after the circulation has been cut off by forcible compression 

 of the aorta. 



3d. When, in animals which have been thrown into a high 

 fever by the injection of putrid matters, a sensitive nerve is 

 stimulated, a rise of blood pi-essure occurs as in the normal 

 condition, but no change of temperature. 



Dr. Heidenhain believes that when the blood pressure rises the 

 blood current moves more rapidly, and that the fall of tempera- 

 ture is due to the surface blood being returned more quickly to 

 the internal organs and thereby cooling them more rapidly than 

 normal. It seems scarcely necessary to point out that if the 

 blood is returned more rapidl}' to the interior, it of necessity 

 remains upon the exterior for a shorter period, and is cooled 

 less than normal. It makes no difference whether a quart of 

 fluid cooled one-tenth of a degree, or a pint cooled two-tenths 



