16 THE TONER LECTURES. 



of a degree, is returned in a given time so far as the temperature 

 is concerned. More than tliis, in a very quiclv passage the blood 

 probably loses less than a proportionate amount of caloric. Be 

 these things as they may, the second and third experimental 

 facts seem, to my mind, entirely sufficient to prove the incor- 

 rectness of the theory of Heidenhain — a theory whose utter 

 improbability is shown by the circumstance that in some of his 

 experiments, though the animals were wrapped in wool, yet the 

 temperature fell steadily after galvanization of ii nerve. Under 

 such cii'cumstances it seems incorrect to attribute the fall of 

 temperature to increased evolution of heat from the body 

 owing to changes in the circulation. 



The work of Heidenhain has been reviewed and extended by 

 Dr. F. Riegel (Pjiiiger's Archio, Bd. iv. 1871). 



In Dr. Riegel's experiments the fall of temperature did not 

 always occur when the nerve was irritated, although the pressure 

 always rose. Moreover, he noticed that the temperature usually 

 remained at the minimum point for a long time after the with- 

 drawal of the stimulus, although the blood pressure returned 

 at once to the normal point. 



The experiments and results of Heidenhain were, indeed, not 

 entirely novel. The same ground appears to have been covered 

 by Mantigazza. Where his memoir is published I am unable to 

 say, but his results and conclusions, as quoted without refer- 

 ence, by Bedard (Archives Generales, VI. Serie, t. xix., p. 35), 

 are as follows : — 



1. Intense pain transmitted by spinal nerves and the skin 

 causes a rapid fall of temperature, which in the rabbit amounts 

 to from 0.68° C. to 2.48° C. ; the mean being 1.27° C. 



2. The temperature falls perceptil>ly during the first minute, 

 and arrives at its maximum in ten to twelve minutes. 



3. The lowered temperature may last for an hour and a half. 



4. The fall is most marked when the pain does not give origin 

 to muscular spasms. 



