200 FORMATION OF SUGAR IN THE LIVER. 



CHAPTER IX. 



FORMATION OF SUGAR IN THE LITER. 



BESIDE the secretion of bile, the liver performs also another 

 exceedingly important function, viz., the production of sugar by a 

 metamorphosis of some of its organic ingredients. 



Under ordinary circumstances a considerable quantity of sac- 

 charine matter is introduced with the food, or produced from 

 starchy substances, by the digestive process, in the intestinal canal. 

 In man and the herbivorous animals, accordingly, an abundant 

 supply of sugar is derived from these sources; and, as we have 

 already shown, the sugar thus introduced is necessary for the proper 

 support of the vital functions. For though the saccharine matter 

 absorbed from the intestine is destroyed by decomposition soon 

 after entering the circulation, yet the chemical changes by which 

 its decomposition is effected are themselves necessary for the proper 

 constitution of the blood, and the healthy nutrition of the tissues. 

 Experiment shows,' however, that the system does not depend, for 

 its supply of sugar, entirely upon external sources : but that sac- 

 charine matter is also produced independently, in the tissue of the 

 liver, whatever may be the nature of the food upon- which the 

 animal subsists. 



This important function was first discovered by M. Claude Ber- 

 nard 1 in 1848, and described by him under the name of the glyco- 

 genic function of the liver. 



It has long been known that sugar may be abundantly secreted, 

 under some circumstances, when no vegetable matters have been 

 taken with the food. The milk, for example, of all animals, car- 

 nivorous as well as herbivorous, contains a notable proportion of 

 sugar ; and the quantity thus secreted, during lactation, is in some 

 instances very great. In the human subject, also, when suffering 

 from diabetes, the amount of saccharine matter discharged with the 



1 Nouvelle Fonction du Foie. Paris, 1853. 



