590 Experiments 



Their work, which develops, confirms, or rectifies my former at- 

 tempts, has shown that the absolute and relative proportion of the 

 gases of the blood is subject to numerous variations. 



But I limit myself for the moment to the study of those varia- 

 tions that may be important in the subject with which I am con- 

 cerned at present. 



Now we are considering here experiments made in the lapse of 

 two or three hours at most. The only influences which can act in 

 this case are: (1) the former bleedings; (2) the animal's respiratory 

 rate; (3) its state of repose or agitation. 



MM. Mathieu and Urbain (loc. cit., page 14 et seq.) attach 

 much importance to the former bleedings. According to them, if 

 20 cc. of arterial blood are extracted from a dog, in a second bleed- 

 ing of 20 cc. there will be considerably less oxygen and carbonic 

 acid; successive bleedings would increase these differences. On the 

 average, for bleedings of 20 cc. made at intervals of an hour and 

 a half, we should have total diminutions of 1.25 cc; 2.25 cc; 3.00 cc; 

 3.50 cc; 3.75 cc After a bleeding of 60 cc, the difference would be 

 on the average 2.50 cc, and after a bleeding of 150 cc, 3.91 cc 



According to them, these modifications would be due principally 

 to the diminution in vascular tension; in fact, they would not be 

 noted if after the first bleeding a quantity of water equal to the 

 quantity of blood removed were injected into the vessels. 



The carbonic acid would vary under the influence of successive 

 bleedings in the same direction and following a higher proportion 

 than the oxygen. 



As for me, I have never noticed such considerable differences 

 in the gaseous content of blood drawn repeatedly from the vessels. 

 Often the numbers obtained remained absolutely identical, when 

 the animal was at rest. This happened, for example, in the follow- 

 ing experiment. 



Experiment CLVI. July 18. Large shepherd dog. 

 At 2 o'clock, drew 44 cc. of blood from the femoral; animal per- 

 fectly quiet .... A 



Drew next 43 cc. of blood from the same artery . . . . B 

 At 3:30, drew 42.5 cc. from the same artery . . . . C 

 Blood A contains per 100 volumes: O2 21.4; CO 39.5. 

 Blood B contains per 100 volumes: O 21.2; CO 40.1. 

 Blood C contains per 100 volumes: O2 21.5; CO 38.6. 



The numerous experiments which will be reported in the present 

 chapter show frequently that successive bleedings do not give such 

 unlike results as one might think from the conclusions of MM. 

 Urbain and Mathieu. 



