104 Chapter VI 



With the blood-gas pump : 



Oxygen absorbed per min. 



Besting pancreas Active pancreas 



40 c.c. -53 c.c. 



23 c.c. -31 c.c. 



The Liver. Lastly we come to an organ which is perhaps more 

 obscure than any of which we have yet treated the liver. It is 

 possible to express the mechanical work performed by muscle for it 

 is doing a definite thing ; it is possible in the case of the kidney to 

 lay down lines for calculating at least the minimum work done by 

 that organ ; but who shall express in units what the liver is about. 

 Its functions are so manifold and in many cases so ill understood, and 

 the evidence of those functions is so difficult to estimate even when 

 they are understood, that at present there seems to be but little hope 

 of getting any accurate notions of its work. All that we can do is to 

 attempt to excite it by what we may regard as its normal stimulus, 

 namely the presence of food in the intestine. It seems at least a fair 

 assumption that the liver will increase in activity during digestion. 



But the estimation of the oxygen used by the liver offers a very 

 difficult surgical problem ; fortunately it fell into the hands of a 

 skilful operator in the person of Shore, and it proved possible to 

 attain reliable results in a very considerable percentage of the 

 experiments. 



The blood had to be collected from 



(1) an artery, 



(2) the portal vein, 



(3) the hepatic vein, 



in such a way that one could obtain one's samples and measure the 

 rate of flow in each of the two last vessels, without upsetting the 

 vascular conditions of the liver. 



This is perhaps scarcely the place to describe the operative pro- 

 cedure in detail ; in a few words however the blood which runs into 

 the inferior vena cava from all organs except the liver is conveyed in 

 a hirudinised animal round to the superior vena cava. The vena cava 

 inferior is then tied above the renal veins and a cannula inserted 

 just above the ligature. By pinching the vena cava in the region of 

 the diaphragm, the blood from the liver may be collected by the 

 cannula. For the collection of the portal blood a cannula is intro- 

 duced into the splenic vein. Into this cannula the blood may be 



