PRODUCTION OF SUGAR IN THE LIVER. 305 



The only other question that has been raised with regard 

 to the possible presence of sugar or sugar-forming matter in 

 the blood of the portal vein has been that inosite (C 12 H ia O 12 ), 

 a substance discovered by Scherer in the muscular tissue of 

 the heart, 1 might be introduced into the portal blood with 

 the animal food. But even if inosite should be contained 

 in food and be detected in the blood of the portal system, 

 it cannot possibly have any thing to do with the glycogenic 

 process, and it is not known that it has any relations to the 

 sugars. Anhydrous inosite is isomeric with anhydrous glu- 

 cose, but it does not respond to any of the copper-tests, and 

 is unfermentable. a 



In view of all these facts, there can be no doubt that the 

 blood carried to the liver by the portal vein does not contain 

 sugar, in animals fed solely upon nitrogenized matters. The 

 quantity of blood carried to the liver by the hepatic artery 

 is insignificant ; and, although the arterial blood may tem- 

 porarily contain a trace of sugar, as we shall see further on, 

 this need not complicate the question under consideration, as 

 the presence of sugar in the blood of the hepatic artery is ex- 

 ceptional, and its proportion, when it exists, is very minute. 



Examination of the Blood of the Hepatic Veins for 

 Sugar. It is upon this question that the whole doctrine of 

 the sugar-producing function of the liver must rest. If it 

 can be proven that the blood, taken from the hepatic veins 

 during life or immediately after death, normally contains 

 sugar, while the blood distributed to the liver contains neither 

 sugar nor any substance that can be immediately converted 

 into sugar, the inevitable conclusion is that the liver is a 

 sugar-producing organ. We will, consequently, examine 

 this part of the question with the care which its importance 

 demands. 



1 SCHERER, Ueber eine neue, aus dem Muskelfleische, gewonnene Zuckerart. 

 Annalen der Chemie und Pkarmacie, Heidelberg, 1850, Bd. Ixxiii., S. 322, et seq. 

 8 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 264. 

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