CHAP. IV.] INFLUENCE OF BLOOD-SUPPLY ON SECRETION OF BILE. 283 



The observations of the Author, with which independent unpublished 

 observations of -Wertheimer concord, have shewn that cholohsematin does not 

 exist preformed in the bile of the ox or sheep at the moment of death, but 

 that the four-banded body is rapidly formed by the oxidation of a chromo- 

 gen existing in the bile when the liquid comes in contact with air. The 

 discovery of this fact does not, however, in the least detract from the 

 scientific value of Wertheimer's observations. 



The Influence of the Blood-supply on the Secretion of Bile. 



Does the liver The blood-supply of the liver will be discussed in 



bi * e detail, in Book III, in connection with the general 

 frommaterials , . , , ',, . , . ,, 



conveyed to it processes which have their seat in that organ, and the 



by the blood of secretion of the bile will again be considered in relation 

 the portal vein to these processes. In this place it seems, however, 

 orof the hepatic expedient to refer to a question which has prompted 

 many researches and given rise to endless discussion, 

 the question, namely, as to whether the liver secretes bile at the 

 expense of the blood conveyed to it by the portal vein or by the 

 hepatic artery. 



If the view which has been expressed at the commencement of 

 this chapter be correct, that the bile is to be looked upon as a 

 comparatively insignificant by-product resulting from the extremely 

 complex and diverse chemical operations which have their seat in the 

 liver, then the hypothesis that bile is normally formed at the expense 

 of the blood of the hepatic artery would appear most improbable. 

 The relations of the liver to the portal vein, and through it to 

 the organs of digestion : the large quantity of blood which reaches 

 the liver through the portal vein, especially during the period of 

 high digestive activity : the exceptional manner in which the portal 

 vein, after the manner of an artery, splits up into capillaries : besides 

 many other anatomical and physiological considerations, afford 

 irresistible arguments in favour of the view that the liver, which 

 takes its origin as a mass of glandular cells in close connection with 

 the mid-gut and which is placed in the path of the blood returning 

 from the organs of digestion, carries on its chief operations mainly at 

 the expense, and with the help, of the materials which the portal 

 blood conveys to it. 



Yet certain well-ascertained observations render it certain that 

 if, through abnormal circumstances, the flow of blood through the 

 portal vein be interrupted, the secretion of bile may continue, before 

 the circulation of portal blood by means of collateral channels can 

 possibly have been established. There can be no doubt that the 

 principal part played by the hepatic artery and its branches is to 

 supply blood to the connective tissue framework of the liver, to 

 supply the gall-bladder and the hepatic ducts, and even to furnish 

 the interlobular branches of the portal vein, with their vasa vasorum. 

 In the liver, however, as in almost every organ, an anastomotic con- 

 nection exists between the various vessels which supply it ; and thus 



