364 COOLING OP ANIMALS EXPOSED TO GREAT HEAT. 



■witlioat limit, no limit but the death of the animal, which is its necessary 

 consequence. In these experiments I ascertained the tem- 

 perature of the animals by a method, of the accuracy of 

 which (here can be no doubt; that is, by introducing a 

 considerable way into the rectum the bulb of a thermo- 

 meter purposely made very small. I found a similar in- 

 crease of temperature in the human subject, by means of a 

 A man in hot thermometer introduced into the mouth: and I even ob- 

 ^poiir with his ggj.yg^ jj_ ^gj,y. strikingly in a case, where the head could be 

 aftected only by means of the circulation ; that of a person 

 placed in a box filled with hot vapour, but having his head 

 out of it 

 The faculty of It follows from these facts, that the faculty af producing 

 producing cold ^^jj jg Q^u^h more limited than is commonly supposed ; not 

 that it is imaginary. Too many facts attest its existence, 

 for it to be doubted: it is desirable, therefore, to ascer- 

 tain its cause; and this I shall attempt to do. 

 Its cause sup- ^ ^^^^ ^^'^ above, that some suppose this cause to be 

 posed to be the the Same with that of animal heat; and they ground this 

 same with tliat . . ., i. i- ^l • ^ /• t-.i i j 



of producing opinion on the results of the experiments of Blagden and 



fceat. Fordyce, from which it would seem we may infer, that 



animals preserve a uniform temperature, whatever may be 

 the heat of the surrounding medium ; and that consequent- 

 ly their faculty of producing cold is as decided as that af 

 This is a mis- producing heat. Indeed, if it were thus, it would be na- 

 ^'■^^^' tural to conceive this uniformity of temperature as one and 



the same phenomenon, originating from a single cause : but 

 this not being the precise fact, as I have shown, we may 

 presume the conclusion to be erroneous. 

 Proof f a There is one observation, that tends strongly to support 

 similar faculty this opinion. It is, that cold-blooded animals possess the 

 anirnSs^^^^''^*^ faculty of preserving a temperature below that of the sur- 

 rounding medium, when this is elevated, as much or more 

 than warm-blooded animals: though, if this faculty arose 

 from the same cause, as that which produces animal heat, 

 cold-blooded animals should be nearly destitute of it. The 

 truth of this assertion I have shown by several experi- 

 ments in the paper already quoted ; and the following, 

 •which I lately made, appear to me to render it unques- 

 tionable. 



lo 



