FORMATION OF SUGAR IN THE LIVER. 207 



lactates of soda and potassa. Bat whatever be the exact mode of 

 its transformation, it is certain that the sugar disappears rapidly ; 

 and while it exists in considerable quantity in the liver and in the 

 blood of the hepatic veins and the right side of the heart, it is not 

 usually to be found in the pulmonary veins nor in the blood of the 

 general circulation. 



About two and a half or three hours, however, after the ingestion 

 of food, according to the investigations of Bernard, the circulation 

 of blood through the portal system and the liver becomes consider- 

 ably accelerated. A larger quantity of sugar is then produced in 

 the liver and carried away from the organ by the hepatic veins ; 

 so that a portion of it then escapes decomposition while passing 

 through the lungs, and begins to appear in the blood of the arterial 

 system. Soon afterward it appears also in the blood of the capil- 

 laries; and from four to six hours after the commencement of 

 digestion it is produced in the liver so much more rapidly than it 

 is destroyed in the blood, that the surplus quantity circulates 

 throughout the body, and the blood everywhere has a slightly sac- 

 charine character. It does not, however, in the healthy condition, 

 make its appearance in any of the secretions. 



After the sixth hour, this unusual activity of the sugar-producing 

 function begins again to diminish ; and, the transformation of the 

 sugar in the circulation going on as before, it gradually disappears 

 as an ingredient of the blood. Finally, the ordinary equilibrium 

 between its production and its decomposition is re-established, and 

 it can no longer be found except in the liver and in that part of 

 the circulatory system which is between the liver and the lungs. 

 There is, therefore, a periodical increase in the amount of unde- 

 composed sugar in the blood, as we have already shown to be the 

 case with the fatty matter absorbed during digestion; but this 

 increase is soon followed by a corresponding diminution, and during 

 the greater portion of the time its decomposition keeps pace with 

 its production, and it is consequently prevented from appearing in 

 the blood of the general circulation. 



There are produced, accordingly, in the liver, two different secre- 

 tions, viz., bile and sugar. Both of them originate by transforma- 

 tion of the ingredients of the hepatic tissue, from which they are 

 absorbed by two different sets of vessels. The bile is taken up by 

 the biliary ducts, and by them discharged into the intestine ; while 

 the sugar is carried off by the hepatic veins, to be decomposed in the 

 circulation, and become subservient to the nutrition of the blood. 



