HIDDEN PROCESSES 145 



after circulating through the liver, is carried 

 off by a single vein, the hepatic vein, which 

 pours it into the systemic venous circulation. 

 There it mixes with other venous blood, 

 reaches the right side of the heart, passes to 

 the lungs (pulmonary circulation), is sent on to 

 the left side of the heart, and is then propelled 

 by the systemic circulation to all parts of the 

 body. Thus, as already mentioned, the whole 

 of the blood that has circulated through the 

 alimentary canal passes through the liver 

 before it reaches the general venous system. 

 This is the portal circulation. In the cells o! 

 the liver very active metabolic changes take 

 place, new substances are formed, complex 

 bodies are split up, possibly red corpuscles are 

 decomposed, and as the result of all this, we 

 have bile formed, which, as already seen, 

 passes into the first portion of the small bowel, 

 the duodenum. The formation of bile was at 

 one time regarded as the proper function of the 

 liver. But it is now known that this is not 

 the case. The bile is only a by-product led 

 off from this remarkable manufactory. 



77. As already pointed out, the blood with 



