The regulation of the supply of oxygen to the tissues 135 



this proved to be exactly the reverse of what takes place. The fact 

 is (1) that the blood in the hepatic vein leaving the liver on the average 

 contains about as much oxygen as does that in the portal vein. The 

 comparison is shown in the following table : 



Oxi/yen in 1 c.c. of blood entering the liver by the portal 

 vein and leaving it by the hepatic vein. 



Mean of 

 Total 10 exps. 



Portal vein -041 -049 -114 -038 -033 -033 -017 '032 -039 -094 -490 -049 

 Hepatic vein -042 -052 -088 "017 "074 -029 '000 -004 -056 -088 -450 -045 



It is impossible to discuss the fate of the individual corpuscles on 

 their way through the liver. We only have the data furnished by a 

 knowledge of the initial and final conditions of the blood with regard 

 to the organ. When we speak of the oxygen which it receives from 

 the hepatic artery we mean the amount of oxygen in 1 c.c. of 

 the arterial blood minus the oxygen in 1 c.c. of blood from the 

 hepatic vein multiplied by the amount of blood entering the liver 

 from the artery per minute ; and similarly with regard to the portal 

 blood, the quantity of oxygen which the liver acquires from this 

 channel is regarded as the oxygen in 1 c.c. of portal blood minus that 

 in 1 c.c. of hepatic venous blood, multiplied by the number of c.c. of 

 blood entering the liver by the portal vein per minute. By the 

 addition of these two quantities (the oxygen acquired from the hepatic 

 artery and that acquired from the portal vein) we arrive at the total 

 quantity of oxygen used by the liver. 



The following example which is typical will indicate what we 

 mean : 



Oxygen in 1 c.c. of blood in hepatic artery -128 c.c. 



,, ,, portal vein -033 c.c. 



,, ,, ,, hepatic vein -029 c.c. 



Bate of flow of blood in hepatic artery 16 c.c. per minute 



,, ,, portal vein 20 c.c. per minute 



Oxygen taken from hepatic artery (-128- -029) x 16 = 1-58 



portal vein (-033 - -029) x 20 -08 



Oxygen used by liver per minute =1-60 



In the majority of experiments the whole amount of oxygen 

 brought to the liver by the portal blood would not suffice for its 

 needs, whilst that brought by the hepatic artery would more than 

 suffice as the following figures show. 



