A STUDY IN MORBID AND NORMAL IMIYSIOLOGY. 89 



MfN. Seo. Temp. RE.AIAEKS. 



21:30 101.25 AiiKsthesia has been induced and the opposilu crui-al uervo twposed, which was used 



throughout the rest of the cspcnmeut. 



22 101.5 Curreut ap[ilicd. 



22:30 101.5 Current broken. 



23:30 101.02 Eabbit squealing and struggling. 



25 101.62 Current applied, giving rise to violent struggles and cries. 



26 101.75 Current brokeu. 



27 101.15 

 29 101.5 

 32 101.13 

 35 100.87 

 40 100.25 

 47 99.62 



49 9?.5 Rabbit killed. 



An examination of tliesc records will show (h;it rnvoly did tlio tompovatiivo fall 

 whilst the current was being applied, and that in several cases there was even a per- 

 ceptible rise, amounting to from an eighth to a half of a degree. This rise I believe 

 to have been due to the rise of blood pressure and to the violent muscular exertion 

 which the pain caused. It certainly occurred at tlic period at which the blood pres- 

 sure was increased. In many experiments upon the effects of irritation of a sensitive 

 nerve on the arterial pressure, I have found that if tlie rise occur it is immediate, 

 and that in a very brief time after the cessation of the irritation the arterial pres- 

 sure becomes normal. In all of my experiments, here reported, the fall of tempera- 

 ture did not fairly commence until after the period of disturbance of the circulation 

 had passed by; in most cases it was very persistent and progressively increased for 

 many minutes. In Experiment 67 the fall amounted to three degrees and three- 

 quarters, and did not reach its maximum until twenty-three minutes after the last 

 irritation of the sensitive nerve. It is therefore highly improbable that the fall 

 of temperature is due to disturbances of tlie cu'culation, since, at the time of the 

 fall of temperature, the circulation is not profoundly affected. The time of the 

 fall and its permanence indicate that (lie full of temperature which results from the 

 irritation of a sensitive nerve, is independent of the state of the circidation as vieasured 

 hy the arterial pressure. 



If this proposition be correct, and if, as has already been rendered probable, 

 there is above the medulla a centre which has the power of directly or indirectly 

 inhibiting heat production, it is reasonable to expect that, after section of the 

 medulla at the border of the pons, galvanization of a sensitive nerve will fail to 

 affect the temperature. Further, if such galvanization does fail to affect the tem- 

 perature, it is evident that a heat-controlling centre of some kind, situated above 

 the pons, must exist, since the general circidation and respiration are affected as in 

 the normal animal. Such is the reasoning, and in order to test what the fact may 

 be, the following experiments were performed. 



Experiment 68. 



A stout young dog. Medulla, as demonstrated at autopsy, nearly rut llirongh at its junction with 

 the pons. 



Time. Temp. KEJI.VRKS. 



1 P. M. 101°.75 F. Galvanization of a sensitive nerve with .an intense Faradic current for half a minulc 



had no perceptible effect on the bodily temperature. Dog watched many minutes. 

 12 June, 1830. 



