440 EXCRETION. 



except that a portion is temporarily retained in a diverticulum from the main duct, the 

 gall-bladder. 



The two distinct functions of the liver now recognized by many physiologists, namely, 

 the secretion of bile and the formation of sugar, have led to the question of the existence 

 in the liver of two anatomically distinct portions or organs, corresponding to its double 

 physiological function. This view, indeed, has been advanced by several eminent anato- 

 mists. Robin recognizes two distinct parts in the liver ; a biliary organ and a glycogenic 

 organ. He regards the lobules, with their liver-cells and blood-vessels, as the parts con- 

 cerned in the glycogenic function of the liver, and the little glands which open into the 

 biliary ducts all along their course (see Fig. 133) and are arranged on the duct " in the 

 form of leaves of fern," as the biliary organ. The same independence of the glycogenic 

 and biliary portions of the liver has been argued by others. 



The fact that bile is found in the lobular canals and the demonstration of the direct 

 communication of these canals with the excretory biliary ducts are powerful arguments 

 in favor of the view that the bile is formed in the lobules, and probably by the liver-cells. 

 What, then, is the function of the little acini connected exclusively with the biliary ducts? 

 The similarity of their structure to that of the ordinary mucous glands, and to the mucous 

 glands of the gall-bladder especially, would lead to the supposition that they secrete a 

 mucous fluid. It is well known that the bile taken from the gall-bladder contains more 

 mucus than that discharged directly from the liver ; but the bile of the hepatic duct in 

 most animals is somewhat viscid and contains a certain amount of mucus. This is the 

 view entertained by Sappey, who states that the bile is viscid in different animals in pro- 

 portion to the development of these little glands ; and, in the rabbit, in which the glands 

 do not exist, the bile is remarkably fluid. 



Inasmuch as there is no direct evidence that the racemose glands attached to the 

 excretory biliary passages have any thing to do with the secretion of the essential con- 

 stituents of the bile, and as they are not even to be found in some animals that produce a 

 considerable quantity of bile, we must regard the question of the isolation of two organs 

 in the liver, one for the secretion of bile and the other for the production of sugar, as still 

 unsettled. There is no evidence, indeed, that the bile is secreted anywhere but in the 

 hepatic lobules. 



Secretion of Bile from Venous or Arterial Blood. Numerous experiments have been 

 made with the view of determining whether the bile be secreted from the blood brought 

 to the liver by the portal vein or from the blood of the hepatic artery. The immense 

 quantity of blood distributed in the liver by the portal vein led first to the opinion that 

 the impurities were separated from this blood to form the bile, and that the hepatic 

 artery had little or nothing to do with the secretion. But, since Bernard discovered the 

 glycogenic function of the liver, this subject has assumed additional importance ; and it 

 becomes a question whether the materials for the secretion of bile may not be furnished 

 by one vessel (the hepatic artery), while the other (the portal vein) is specially con- 

 cerned in the formation of glycogenic matter. This theoretical view, however, is not 

 carried out by well-established anatomical facts or by physiological experiments. It is 

 not yet possible to separate the liver anatomically into two organs, one for the secretion 

 of bile and the other for the production of sugar. It seems certain, also, from numerous 

 experiments, that bile may be secreted from the blood of the portal vein after a ligature 

 has been applied to the hepatic artery ; and it is equally certain, from the recent experi- 

 ments of Ore, that, if the portal vein be obliterated so gradually that the animal does not 

 die from the operation, bile is secreted from the blood of the hepatic artery. In support 

 of this view, several instances of obliteration of the portal vein in the human subject are 

 cited in works upon physiology. In a note to the communication of Ore in the Comptes 

 rendus, Andral reports the case of a patient that died of dropsy, and on post-mortem 

 examination the portal vein was found obliterated. In this instance the gall-bladder 



