232 EXTENT OF THE DAILY INTERCHANGE OF GASES. 



It would certainly be highly interesting to determine whether the temperature 

 of the expired air undergoes change by reason of inflammations, disturbances of 

 the circulation, or degenerations in the lungs. 



Mosso and Rondelli allowed dogs to breathe air at a temperature of from 

 150 to 160 C., and found that the air in the bronchi was of a higher temperature 

 (39.3 or 37.8 C.) than the rectum. 



The diminution in volume of the expired air mentioned already 

 is compensated for by the warming of the inspired air in the air- 

 passages, and by the tension of the contained aqueous vapor, so that 

 the volume of the air expired is even one-ninth greater than that of the 

 air inspired. 



Exceedingly small quantities of ammonia are admixed with the 

 expired air, amounting to about 0.0204 gram in twenty-four hours; they 

 are probably evolved from the blood. 



Small quantities of hydrogen and marsh-gas (CH 4 ), both absorbed 

 from the intestines, are likewise exhaled. Reiset observed that in herbiv- 

 orous animals the marsh-gas exhaled in twenty-four hours amounted to 

 as much as 30 liters. 



The aqueous vapor condensed by low temperature from the expired air of 

 some persons acts as a poison when injected subcutaneously, in consequence of 

 the presence of a volatile base. These are exceptions, however. 



EXTENT OF THE DAILY INTERCHANGE OF GASES. 



As more oxygen is normally taken in than is excreted in the carbon 

 dioxid (equal volumes of oxygen and carbon dioxid containing equal 

 quantities of oxygen), a part of the oxygen taken in must be used for 

 other oxidation-purposes. According to the extent of the latter, there 

 must be considerable variation in the relation of the inspired oxygen to 

 the expired carbon dioxid (the quotient *, which is given as being 

 on an average 0.916 during normal, quiet respiration). Within the 

 limits of the normal vital processes, not only may the excretion of 

 carbon dioxid be less than the stated average, but it may even be con- 

 siderably in excess of the absorption of oxygen. With such varia- 

 tions it is evident that the estimation of the amount of carbon 

 dioxid alone cannot be a reliable measure of the total interchange of 

 gases. A complete insight into the gaseous balance can be obtained 

 only by a simultaneous estimation of the oxygen taken in and of the 

 carbon dioxid given off. 



SUMMARY OF THE GASEOUS INTERCHANGE. 



Absorption in twenty-four hours : Excretion in twenty-four hours : 



Oxygen, 744 gm. =516,500 cu. cm. Carbon dioxid, 900 gm. =455,500 cu. 

 (Carl Vierordt) . cm. (Carl Vierordt) , hourly 31.5- 



5 1 1-658 gm. (Speck). 33 gm. (J. Ranke) ; 32.8-33.4 



(The volumes are determined for o gm. (v. Liebermeister) ; 34 gm. 



and the mean barometer.) (Panum) ; 36 gm. (Scharling). 



Water, 640 gm. (Valentin); 330 gm. 

 (Carl Vierordt). 



FACTORS INFLUENCING THE EXTENT OF THE RESPIRATORY 

 EXCHANGE OF GASES. 



The process of carbon-dioxid formation consists probably of two 

 separate stages. In the first place, through the presence of oxygen 



