Gases of the Blood 653 



At 290 mm.: 2 16.4; C0 2 13.0; N 0.6. 

 At 87 mm.: O* 11.3; CO 8.6; N 0.4. 

 At 26 mm.: CK> 7.2; CO* 7.0; N 0.2. 



Experiment CCVIII. February 18. Defibrinated dog blood, interior 

 temperature of the flask 38°. Agitation at normal pressure; blood con- 

 tains O2 20.2. 



At 38 cm.: 2 17.7. 



At 19 cm.: 0» 16.4. 



Experiment CCIX. February 26. Defibrinated dog bleod. Agita- 

 tion at normal pressure; interior temperature of the flask 38°; the 

 blood contains 2 18.2; C0 2 10.1. 



At 38 cm.: 2 14.8; C0 2 6.8. 



At 19 cm.: 2 10.6; C0 2 7.0. 



These four experiments, when we get the averages, setting the 

 origins of the graphs at 20, give us graph B of Figure 43. 



We see that the curve B dips much more rapidly than the 

 preceding A, and more nearly approaches the one which, taken 

 from Column 8 of Table X, expresses the oxygen changes in the 

 living animal, and is represented here in C. In other words, the 

 contradiction noted loses much importance when we supply the 

 temperature conditions given by the bodies of warm-blooded 

 animals. 



However, our analyses show that the arterial blood of a living 

 animal subjected, for example, to a half atmosphere, could absorb 

 a quantity of oxygen much greater than that which it really 

 contains. 



That is because the intra-pulmonary agitation of the blood with 

 the air is no longer carried on in satisfactory conditions. Even at 

 normal pressure, as we have seen, the arterial blood is not saturated 

 with the oxygen which it can hold; it reaches that point of satura- 

 tion — or nearly so— only after exaggerated respiratory efforts, 

 which bring on an exaggeration of circulatory rapidity. At a half 

 atmosphere, to obtain the same result as at ground level, the activity 

 of intra-pulmonary mixing would have to be doubled; the respira- 

 tory movements must be doubled in amplitude and rapidity; the 

 heart movements must be doubled in strength and number. That 

 is evidently impossible. 



Summarizing, the conclusions of M. Fernet's work are legitimate 

 only under the conditions of pressure and temperature (16°) at 

 which he worked. At lower pressures, at body temperature, the 

 part of the oxygen which he considers as chemically combined in 

 the blood because it is independent of the pressure, really follows 

 the pressure changes, although considerably less quickly than a 



