638 



Experiments 



5 o'clock; Took 30 cc. of venous blood . . . 



5:07; Took 30 cc. of arterial blood . . . . < 



Air from the bag . . . . c 



5:15; Rectal temperature 34°. 



5:20; Arterial blood, 30 cc; animal dying . 



5:30; Venous blood, animal dead . . . . D' 



C 



Figure 40 makes it still easier to comprehend the results of 

 these three experiments in regard to the variation of the gases of 

 the blood; as usual, the quantities of gas are plotted on the vertical 

 axis, the oxygen content and the barometric pressure which cor- 

 responds to it are plotted on the axis of the x's. The results of 



Experiment CXC are marked by dotted lines ; those of 



Experiment CXCI by dashes ; those of Experiment CXCII 



by dashes and dots — . — . — . — . 



We see at first glance that in both the venous and the arterial 

 blood the oxygen and the carbonic acid diminish when the tension 

 of the oxygen breathed diminishes. 



We see also that the difference in gaseous content between the 

 arterial and the venous blood remains almost constant until the 

 oxygen in the air is about half exhausted, that is, in the neighbor- 

 hood of a half-atmosphere. Beyond that, the graphs draw closer 

 together. 



So, up to a certain degree, the venous blood loses oxygen in the 

 same quantity as the arterial blood; that deserves some attention. 



Let us take, for example, Experiment CXC. At the beginning, 

 the arterial blood contains 21.6 of 2 ; the venous blood, 12.4; differ- 

 ence, 9.2; which means that the tissues needed for their regular 

 maintenance and consumed as it passed 9.2 volumes of oxygen for 

 each 100 volumes of blood. 



We drop to a pressure of 41.8 cm., and on account of the de- 

 creased capacity of the blood for oxygen at this pressure (See below 

 in Subchapter V) there is now only 19.6 of this gas in the arterial 

 blood; we find only 10.2 in the venous blood: difference, 9.4. The 

 consumption of oxygen by the tissues has then remained the same, 



