On the different Forms of Breathing. 



109 



cal Theory of Heat," that the heat emitted by an animal should be 

 measured by the amount of oxygen consumed, while I look upon this 

 heat as due exclusively to the CO 2 produced. 



The fact contained in my last paper that the mean volume of 

 oxygen absorbed (not transformed into CO 3 ) in exercise, is the same 

 as that absorbed in the state of rest, shows clearly that the oxygen 

 absorbed is not concerned in the production of heat necessary for 

 muscular exercise. 



JBy an inspection of the following table, it will be clearly seen that 



Oxygen absorbed and Carbonic Acid Expired at Rest, Normal and 



Forced. 



The Author under Experiment. 



the oxygen " absorbed " (not transformed into C0 2 ) under forced 

 breathing was very much less than that absorbed in natural respira- 

 tion, instead of being in excess, as might have been expected if the 

 oxygen " absorbed " was concerned in the production of the heat re- 

 quired for the labour of forced breathing. Subsequent investigation 

 showed that the reduction of the oxygen " absorbed " in forced breath- 

 ing was due to the fact that, although the C0 2 had returned to the 

 normal in the above experiments, still the " absorbed " was short 



