208 FUNCTIONS OF NUTRITION. 



killed the animal by section of the medulla oblongata, immediately 

 placing a portion of the liver in a freezing mixture, and afterward 

 slicing it into boiling acidulated water, has shown that glucose may be 

 demonstrated in the organ within 20 seconds after death. If a portion 

 of the liver, separated while the circulation is going on, be ground to a 

 pulp and plunged into strong alcohol or boiling water, either of which 

 arrests the transformation of glycogen, its decolorized extract will give 

 the reaction of glucose by Fehling's test. We have invariably obtained 

 this result in experiments of this kind,* though the time occupied in 

 taking out the liver tissue and immersing it in alcohol or boiling w^ater 

 was, on the average, but little over six seconds. Bernard, f in a re- 

 examination of the subject after a long interval, found that in dogs and 

 rabbits pieces of the liver, cut out and plunged into boiling water for 

 two or three seconds, constantly contained glucose in nearly the above 

 proportions ; and the same conclusion has been reached by Seegen and 

 Kratschmer J in experiments on dogs, cats, and rabbits, in which the 

 time varied from a few seconds to three minutes. It appears, therefore, 

 that glucose is a normal ingredient of the liver tissue during life. 



Absorption and Disappearance of the Liver-sugar. The glucose 

 produced in the liver from the transformation of glycogen does not 

 remain at the place of its formation. It is absorbed by the blood 

 traversing the capillaries of the organ, and carried away in the current 

 of the circulation. This is shown by the fact that the blood of the 

 hepatic vein, as well as the liver tissue, contains glucose, although 

 there may be none in the portal blood by which the organ is supplied. 

 As the blood, before its entrance into the liver, in these cases, is desti- 

 tute of sugar, and yet contains this substance after its passage, it must 

 acquire its saccharine ingredient in the liver itself. Bernard has shown 

 that if two specimens, one of portal and one of hepatic blood, be taken 

 from the same dog, when fasting or after an exclusive diet of animal 

 food, the former will show no trace of sugar, while the latter will be 

 saccharine. Lehmann || obtained similar results in dogs and horses. 



Glucose, accordingly, although constantly produced in the liver, does 

 not accumulate in the organ during life beyond a very moderate quan- 

 tity. It is only after death, when the circulation has come to an end, 

 and while the transformation of glycogen is still going on, that the 

 proportion of glucose in the liver tissue becomes notably increased. 

 The circulation of blood, so long as it continues, acts like an injection 

 through the hepatic vessels, and extracts from the organ the sugar pro- 

 duced at the expense of its glycogen. 



In this way the blood of the general circulation is supplied with 



* Transactions of the New York Academy of Medicine, 1871. 2d Series, Vol I., 

 p. 28. 



f Comptes Rendus de l'Acade"mie des Sciences. Paris, 1877, tome Ixxxiv., p. 1201 . 



j Archiv fur die gesammte Physiologic. Bonn, 1880, Band xxii., p. 214. 



$ Lefons de Physiologic Experimentale. Paris, 1855, pp. 265, 469. 



|| Comptes Rendus de 1'Academie des Sciences. Paris, 1855, tome xl v p. 585. 



