Gases of the Blood 649 



everything relating to oxygen. It was obtained by assuming that 

 the initial proportion of oxygen at normal pressure was always 20 

 volumes per 100 volumes of blood, and by determining the value of 

 the other numbers by proportions like the following, which applies 

 to Experiment CXCIII: 19 (normal pressure) : 20 = 17.2 (pressure 

 of 56 cm.) : x = 18.1. 



A simple glance will show that, from normal pressure to that of 

 10 to 15 centimeters of mercury, the blood absorbs quantities of 

 oxygen that are almost the same; one or two volumes less, and that 

 is all. It is even very possible that this difference affects only the 

 oxygen dissolved in the plasma, which rises, according to M. Fernet, 

 to 2.88 per 100 volumes of liquid. So our analyses, which go to pres- 

 sures considerably lower than those used by M. Fernet, give results 

 which tend in the direction of the conclusions of this physicist. 



But from 15 centimeters of mercury on, the oxygen escapes from 

 the blood in a far greater proportion than the Law of Dalton would 

 require. There occurs a dissociation of the combination of the 

 oxygen with the hemoglobin, a dissociation whose intensity in- 

 creases rapidly. 



I have made a sort of control experiment using a method nearer 

 that of M. Fernet, since instead of extracting the oxygen progres- 

 sively by agitation at lower and lower pressures, I measured the 

 quantity absorbed by blood that had previously been entirely de- 

 prived of gas. 



Here are the results of three experiments carried out in this 

 way. It will be seen that they agree, in their general trend, with 

 those obtained by the first method. 



Experiment CCII. December 30; pressure 762 mm. 



We prepare two mercury pumps and two apparatuses for extract- 

 ing the gases of the blood, in which absolute vacuum is made. 



From the jugular vein of a dog by means of a syringe 138 cc. of 

 blood is drawn, and this blood is injected into a flask full of air; the 

 blood is defibrinated and oxygenated by long shaking in the flask. 

 89.5 cc. of blood measured in a graduated test tube is passed into one 

 of the pumps; this blood has been filtered through linen and freed of 

 fibrin and air bubbles; the gases are extracted from the blood heated 

 to a temperature of 35° to 39°, until a dull click is heard; the blood 

 is completely reduced. When the extraction has been made, the blood 

 is cooled in cold water to about 10°. 



The analysis of the gases extracted shows that 100 cc. of blood 

 shaken in the air at a pressure of one atmosphere has absorbed 19.8 

 cc. of oxygen. 



Air at a pressure of a half atmosphere is admitted to the empty 

 apparatus; to do this, a long vertical tube, T (Fig. 44) is used, into 



