322 SECRETION. 



blood in living animals, and others, by estimating the pro- 

 portion of sugar in the liver. The latter method must be 

 considered, with an appreciation of the fact that the liver 

 does not normally contain sugar during life ; but it repre- 

 sents, to a certain extent, the activity of the glycogenic 

 function. Still, the facts arrived at in this way must be 

 taken with a certain degree of caution. 



Glycogenesis in the Foetus. In. the early months of foetal 

 existence, many of the tissues and fluids of the body were 

 found by Bernard to be strongly saccharine ; but at this 

 time no sugar is to be found in the liver. Taking the ob- 

 servations upon foetal calves as the criterion, sugar does not 

 appear in the liver until toward the fourth or fifth month of 

 intra-uterine life. 1 Before this period, however, epithelial 

 cells filled with glycogenic matter are found in the placenta, 

 and these produce sugar until the liver takes on its functions. 

 As the result of numerous observations by Bernard upon 

 foetal calves, this function of the placenta appears very early 

 in foetal life, and, at the third or fourth month, has attained 

 its maximum. At about this time, when glycogenic matter 

 begins to appear in the liver, the glycogenic organs of the 

 placenta become atrophied, and are lost some time before 

 birth. 8 



Influence of Digestion, and of Different Kinds of Food. 

 Activity of the digestive organs has a marked influence 

 upon the production of sugar in the liver. In a fasting ani- 

 mal, sugar is always found in the blood of the hepatic veins 

 and in the vessels between the liver and the heart, but it 



1 BERNARD, Lemons de physiologic experimental^ Paris, 1855, p. 82. 



2 BERNARD, Sur une nouvelle fonction du placenta. Journal de la physiologie, 

 Paris, 1859, tome ii., p. 33. Bernard found glycogenic matter in the placenta 

 of animals in which the organ was single, as in the human subject ; but in ani- 

 mals with multiple placenta he did not at first discover the glycogenic organs, 

 which he subsequently found, not in the vascular portion, but attached to the 

 amnion. 



