THE FORMATION OF THE CONSTITUENTS OF BILE. 455 



is much smaller than the quantity calculated to be set free in the formation 

 out of the haemoglobin of the quantity of biliriibin discharged during the 

 same period. Apparently the iron compounds of the hepatic cell have some 

 other work than the simple discharge of iron into the bile. 



The fact mentioned above, that the presence of free hemoglobin in the 

 blood leads not only to an increase of bilirubin in the bile, but also to its 

 presence in the urine, offers some difficulties ; for if the bilirubin be formed 

 out of hemoglobin by and in the hepatic cell, one would expect to find that 

 the whole of it passed into the bile, and that it could not appear in the 

 blood and so in the urine unless reabsorption from the bile passages, due to 

 obstruction took place ; and there is no evidence of any sufficient obstruc- 

 tion occurring in these cases. Indeed the presence of bilirubin in the urine 

 in these cases has been urged by some as an argument that biiirubin is 

 formed in the blood or at least elsewhere than in the liver, and is simply 

 excreted by the liver. Not only, however, as stated above, is there no ac- 

 cumulation of bile in the blood after extirpation of the liver, but that ope- 

 ration prevents the appearance of bilirubin in the urine as a consequence of 

 the presence of free haemoglobin in the blood. The phenomena in question, 

 therefore, do not disprove that the biliruhin is formed in the liver ; they 

 may be taken, however, to show that that formation, viewed as a secretory 

 act, is peculiar, since the hepatic cell appears under certain circumstances to 

 discharge its product of secretion into the blood or lymph as well as into 

 the bile passages. 



392. We may assume then that the hepatic cell has the power of split- 

 ting up the haemoglobin brought to it, and of discharging part as bilirubin 

 while it retains for a time the iron component in some organic combination; 

 and, if we further assume that it works upon the entire haemoglobin we may 

 presume that makes some subsequent use of the proteid component. But 

 are we justified in assuming that the whole work is done by the hepatic 

 cells? Are we to conclude that bilirubin is manufactured by some act of 

 the hepatic cells which includes not only the conversion of haemoglobin into 

 bilirubin, but also the extraction of the haemoglobin from the red corpus- 

 cles as these are streaming slowly through the lobular hepatic capillaries in 

 close contact with the hepatic cells ? Now, as far as we know at present, 

 haemoglobin can only be set free by means of a disintegration of the corpus- 

 cles ; we have no instances of a corpuscle parting with some of its haemo- 

 globin and proceeding on its way otherwise unchanged ; and we have no 

 histological evidence of any disintegration of red corpuscles in the liver cor- 

 responding to the formation of bile. Nor can we draw any conclusion from 

 the result of a comparative enumeration of red corpuscles in the portal and 

 hepatic blood, for these are too insecure to rest any conclusion upon. On 

 the other hand, as we have just seen, the presence in the plasma of the blood 

 of haemoglobin in a free condition is peculiarly potent in exciting the forma- 

 tion of bilirubin. The evidence, therefore, is very strong for the view that 

 as far as the formation of the greater part at least of the bilirubin is con- 

 cerned, the action of the hepatic cell is limited to converting into bilirubin 

 the free haemoglobin offered to it by the portal blood. 



By what means, under normal conditions, is the presence of that free 

 haemoglobin secured ? We have seen reason to conclude from histological 

 appearances that a certain number of red corpuscles undergo change in the 

 spleen-pulp ; and it seems natural to infer that one duty of the spleen is to 

 set free haemoglobin from the corpuscles and thus, through the splenic veins 

 and so the portal vein, to supply the liver with material for bilirubin. But 

 this cannot be the only source, since the secretion of bile continues after 

 extirpation of the spleen. There must, therefore, be other regions of the 



