BY DR. LAUDER BRUNTON. 507 



shows that it is an ingredient of colorless blood corpuscles so 

 long as they are active, but that when they lose their power of 

 motion their glycogen disappears, and is replaced by sugar. 1 

 In early foetal life, the muscular fibres and lungs contain much 

 glycogen, which subsequently diminishes. The liver and other 

 glands, and the nervous system of the embryo, contain little 

 or no glycogen ; but it is found in large quantities in the pla- 

 centa. After birth it is confined almost entirely to the liver 

 and muscles. In the latter it seems to have some^relation to 

 the work done by them, for the quantity present in them is 

 diminished by activity. The glycogen of the liver does not 

 remain in it long, but is soon converted into sugar, so that the 

 large quantity which is present after a meal is quickly dimin- 

 ished by fasting, and disappears altogether during starvation, 

 while that present in the muscles does not increase so much 

 after food, nor is it so quickly lessened by starvation (Weiss). 

 Although both the liver itself and the blood contain a fer- 

 ment which transforms glycogen into sugar, its conversion is 

 probably effected in great measure by the blood, for it takes 

 place more rapidly when the circulation through the liver is 

 quickened. It is uncertain what the use of the sugar in the 

 organism is, but possibly it, as well as gtyeogen, has some- 

 thing to do with muscular action, since the quantity of sugar 

 (or a substance reducing copper) in blood becomes much dimin- 

 ished in its passage through the vessels of contracting mus- 

 cles (Genersich). While Bernard considers that the formation 

 of sugar goes on in the liver constantly during life, this has 

 been denied by Pavy, Hitter, Meissner, and Schiff, who hold 

 that it only occurs after death, or under pathological condi- 

 tions, such as disturbance of the respiration or circulation 

 during life. They base their opinions on the observations that 

 the liver contains little or no sugar when examined imme- 

 diately after death, and that the blood of the hepatic vein does 

 not contain more sugar than that of the portal or jugular veins. 

 It is quite true that sugar is found only in very small amount 

 in fresh livers ; but the smallness of the quantity is in all pro- 

 bability due to the constant circulation through the liver 

 during life, washing the sugar out of it as soon as it is formed 

 (Flint). The statement that the blood of the portal contains 

 as much sugar as that of the hepatic vein, rests on experiments 

 vitiated by the omission to place a ligature on the former while 

 removing the liver, so that the hepatic vein having no valves, 

 the blood from it flowed back into the portal system. When 

 this fallacy is avoided, sugar is found in much larger propor- 

 tion in the hepatic than in the portal vein. To meet the objec- 



1 For the details of this experiment see Med. Chem. Untersuch., 1871, 

 p. 486. 



