2(50 THEORY OF RESPIRATION. 



lungs, like the globules, into more highly oxidized com- 

 pounds ; a certain amount of carbonic acid is formed, 

 of which a part always remains dissolved in the serum 

 of the blood. 



The quantity of carbonic acid dissolved, or of that 

 combined with soda, must be equal in venous and 

 arterial blood, since both have the same temperature ; 

 but arterial blood, when drawn, must, after a short 

 time, contain a larger quantity of carbonic acid than 

 venous blood, because the oxygen of the globules is 

 expended in producing that compound. 



Hence, in the animal organism, two processes of 

 oxidation are going on ; one in the lungs, the other in 

 the capillaries. By means of the former, in spite of 

 the degree of cooling, and of the increased evaporation 

 which takes place there, the constant temperature of 

 the lungs is kept up ; while the heat of the rest of the 

 body is supplied by the latter. 



A man, who expires daily 13-9 oz. of carbon in the 

 form of carbonic acid, consumes, in 24 hours, 37 oz. 

 of oxygen, which occupy a space equal to 807 litres 

 = 51,648 cubic inches (Hessian). 



If we reckon 18 respirations to a minute, we have, 

 in 24 hours, 25,&20 respirations ; and, consequently, 

 in each respiration, there are taken into the blood 

 f'j?|8 1 -99 cubic inch of oxygen. 



In one minute, therefore, there are added to the 

 constituents of the blood 18 X 1*99 = 35'8 cubic 



