178 THE LAWS OF OBGANIC 



as atmopheric air, while that in the latter was 

 one-half. From these results he concluded, that 

 less oxygen is consumed in a heated state of the 

 system than when the medium is cold. 



It is impossible to estimate the changes or con- 

 ditions of the blood by any degrees of alterations 

 which the inspired air undergoes. At one time, 

 when the blood is determined to the internal 

 viscera, by cold or disease, the proportion in the 

 lungs may be calculated at 30, while the natural 

 quantity may be only 10 ; and if this should 

 occur, the air will be vitiated to a greater extent 

 in the former than in the latter case, without the 

 same quantity of heat being produced. It must 

 be obvious to the reflecting mind, that, if the 

 quantity of blood in the lungs be increased three- 

 fold, without the surface which it offers to the 

 air being enlarged to the same degree, that more 

 oxygen may be consumed without the blood 

 having derived the ordinary advantages from the 

 contact. When the proportion of 10 presents its 

 surface of blood to the action of the air, it is proba- 

 ble that this is almost as extensive as that of 30 ; 

 the same capillary vessels are occupied by both ; 

 and if they become congested by the addition of 

 10 or 20, this very state of the vessels may pre- 

 vent the usual complete changes of the blood. 

 In support of this opinion I may observe, that 

 in every instance in which the quantity of san- 

 guineous fluid in the lungs is greater than what 



