AND ANIMAL LIFE. 35 



4. The results of artificial inflation cannot be considered 



as making even a distant approach towards those che- 

 mical changes which occur during the natural state 

 of the system. 



5. The operation of poisons on the nervous system, ac- 



companied by a diminution of temperature, is no 

 proof that this principle is derived from the action 

 or influence of this system, except in so far as its de- 

 rangement disorders the harmony of chemical laws 

 operating in the lungs. 



6. The consumption of different quantities of oxygen, or 



the evolution of different quantities of carbonic acid, 

 cannot, as is the received opinion, be regarded as a cri- 

 terion of the temperature of an animal, because " ani- 

 mal heat is not in the direct ratio to the quantity of 

 oxygen inhaled, but in the inverse ratio to the quan- 

 tity of blood exposed to this principle" 



XLI. In support of the first proposition, it is 

 obvious that, in every kind of muscular exer- 

 tion, attended by expiratory actions, the tempe- 

 rature of the body is augmented ; and I have 

 shown, in the preceding chapter, that this arises 

 from the quantity of blood in the lungs being 

 less than in the unexcited state of the system, 

 not only at the commencement of the invigorat- 

 ed action, but throughout the continuance of its 

 energy. 



XLII. If we diminish the respiratory action, 

 we lessen the generation of animal heat. 



XLIII. If the circulation of blood in the 

 lungs and internal organs be accelerated by 



