CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 749 



cells, while arresting the more difficult metabolic labours of the 

 cells, such as the formation of bile-acids, do not put an end to the 

 lighter task of turning haemoglobin into bilirubin, though so 

 affecting that process also that the bilirubin passes into the blood 

 instead of into the bile passages. In other words the formation of 

 bilirubin is an act independent of and different from the more 

 ordinary secretory activity of the cells. 



481. The question may be asked, Is the secretion of bile 

 independent of or in some way or other connected with the 

 glycogenic activity of the cells ? To this we cannot at present 

 give a definite answer. In some of the invertebrata the cells in 

 the organ, called a liver, which manufacture glycogen, are distinct 

 from those which secrete bile or other digestive juices ; and it 

 might be inferred that in the vertebrate the two actions though 

 taking place, as they certainly do, in the same cell, take place 

 apart and distinct. There are facts which seem to indicate 

 that the two are intimately connected; but we have as yet no 

 exact knowledge concerning the matter. It has been urged 

 that the portal blood is chiefly concerned with the formation of 

 glycogen, and the blood of the hepatic artery with the secretion 

 of bile; but there is no adequate support of this view. It 

 must be remembered moreover that, in addition to the formation 

 of glycogen and the secretion of bile, other metabolic events, 

 especially affecting proteid or at least nitrogenous constituents 

 of the body, are also taking place ; and to these we must now turn. 



