4io 



TEXT-BOOK OF PHYSIOLOGY. 



Thus, 100 grams each of muscle, spleen, and broken bone from a recently 

 living animal exposed to the air for twenty-four hours absorbed respectively 

 50.8 c.c., 27.3 c.c., and 17.2 c.c. of oxygen, while each discharged during the 

 same period 56.8 c.c., 15.4 c.c., and 8.1 c.c. of carbon dioxid respectively. 

 In another series of experiments by a different observer 100 grams of muscle 

 * absorbed in three hours 23 c.c. of oxygen, and 100 grams of bone 5 c.c. of 

 oxygen. Both tissues discharged carbon dioxid in amounts proportional to 

 the oxygen absorbed. The same respiratory changes may be more satis- 

 factorily demonstrated by passing blood through the tissues of isolated 



Atmospheric Air. 



Ox-iss mm,.ng , vr 2O.85 per cent , 

 COz'0.3 Hy, or 0. 04 jeer cent, 

 of a/i atmosphere. 



//S\Z,k/r\\ 



Ox-Tension 



38 mm ff&, 



3 per cent. 



5.5 per cent. 



tfpercent. 

 \CfcTcnswn > 



Alveolus 



Arterial 

 Blood. 



Venous 

 'load. 



OxTension 

 Qjgension 



6 && percent. 



/ft?, 



J4 percent 



38 



Jper eent. 



Tissues. 



FIG. 198. DIAGRAM SHOWING THE RELATIVE TENSION OF OXYGEN AND CARBON DIOXID IN 

 THE LUNGS, IN THE BLOOD, AND IN THE TISSUES. 



organs and the tissues of recently living animals. The analysis of the blood 

 before and after perfusion shows a loss of oxygen and a gain in carbon 

 dioxid. 



Tension of the Gases in the Tissues. As the presence of free oxygen 

 cannot be demonstrated, its tension there must be regarded as nil. The 

 tension of the carbon dioxid is quite high, though difficult of exact deter- 

 mination. It has been estimated at from 45 to 68 mm. Hg., or from 6 to 9 

 per cent, of an atmosphere. 



The variations of tension or pressure of these two gases in the lungs, in 

 different parts of the vascular apparatus, and in the tissues, and their rela- 



