600 Experiments 



which he passes through one of the holes in the wall. Next the 

 rubber tubing and the cock are fastened on. 



The cylinders having been closed and the decompression 

 reached, when one wishes to draw blood, he arranges things as 

 shown in Figure 30. The serre-fine is opened, the syringe whose 

 piston is covered by a layer of water is applied, and suction is made. 

 Since all the connections are immersed in water, no accidents can 

 happen. 



But after the extraction, there remains in the cannula a long 

 clot which generally prevents a new extraction. It was to avoid 

 this difficulty that I devised the stylet of the cannula A, which 

 drove blood back into the animal; only, as I said, I could not be sure 

 of complete closing. I must add that when the extractions were 

 not too far apart, I could sometimes suck out by the syringe the 

 clot which was still diffluent. At other times, immediately after 

 drawing blood, I injected into the cannula a little sodium carbonate 

 solution, to prevent coagulation. 



I drew out thus, as I said, each time, from 30 to 40 cc. of blood. 

 I waited until the decompression had been maintained for several 

 minutes before making the extraction. The blood at normal pres- 

 sure was sometimes taken in advance; but the tendency towards 

 coagulation, which resulted from this practice, caused me usually 

 to take it afterwards. I then took care to wait rather a long time. 

 The account of experiments carried on thus will indicate these 

 details. 



2. Experiments. 



Experiment CLXIII. June 22. Pressure 76.4 cm.; temperature 23' . 

 Large dog, which had been operated on several times the day before: 

 does not seem sick. 



Drew from the femoral artery 46 cc. of blood, at normal pressure; 

 blood quite red .... A 



Placed in the large apparatus; brought down 45 cm., in a half hour; 

 real pressure 31.4 cm.; after 10 minutes, drew from the carotid 46.5 cc. 

 of blood; blood considerably less red . . . . B 



Blood A (76.4 cm.) contains per 100 volumes: O 18.8; CO. 39.7. 



Blood B (31.4 cm.) contains per 100 volumes: O 12.0; CO. 31.0. 



Therefore at a pressure of 31.4 cm., there has disappeared 36.2 

 per cent of the oxygen existing at normal pressure, and 21.9 per cent 

 of the carbonic acid. 



Experiment CLXIV. June 24. Pressure 76 cm., temperature 21°. 

 Large dog. 



Normal pressure: drew from the femoral artery 46 cc. of blood, 

 very red .... A 



Pressure lowered 54 cm., in about three quarters of an hour (real 



