CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 749 



or boiled with dilute acid, the solution, like the raw decoction of 

 liver, loses its opalescence and its port-wine reaction with iodine, 

 but now gives abundant evidence of the presence of sugar, dextrose, 

 if boiling with acid has been employed, maltose chiefly, if an 

 amylolytic ferment has been used. If quantitative determinations 

 be employed it will be found that the amount of sugar obtained 

 is proportionate to the amount of the white powder acted upon ; 

 in other words, the substance forming an opalescent solution is 

 converted into sugar, the solution of which is clear. Obviously 

 the substance is a body allied to starch ; and this is confirmed by 

 its elementary composition, which is found to be C 6 H 10 O 5 or some 

 multiple of this. 



Hence this body is called glycogen. And it is obvious from 

 what has been stated above, that the liver of a well-fed animal 

 at the moment of death contains a considerable quantity of 

 glycogen either in a free state or in such a condition that it 

 is set free by subjecting the liver to the action of boiling water. 

 We may add that it occurs in the liver in the hepatic cells, for 

 the reaction of a port-wine colour given under certain conditions 

 by the hepatic cells, 449, is due to the presence of glycogen in 

 them. 



454. If the liver, instead of being treated immediately 

 upon the death of the animal, is allowed to remain in the body 

 of the dead animal for several hours, especially in a warm place, 

 before a decoction is made of it, the decoction will be found 

 to have little or no opalescence, to be quite or nearly quite 

 clear, to give little or no port-wine reaction with iodine, but 

 to contain a very considerable quantity of sugar. As we said 

 above, the decoction even of a liver taken immediately after death 

 generally contains some little sugar, and the quantity of sugar in the 

 liver appears as a rule to increase steadily after death, the amount 

 of glycogen diminishing at the same time. The rapidity of the 

 diminution of glycogen and the rate of increase of sugar vary much 

 under various circumstances. Moreover, the decrease of the one 

 and the increase of the other are not always strictly proportional ; 

 and indeed some observers have insisted that there is no relation 

 between the two processes. Nevertheless, the broad fact remains 

 that if the liver of the same well-fed animal be divided into two 

 halves, as soon as possible after death, and one half thrown into 

 boiling water immediately, while the other half is left, exposed 

 to some little warmth for several, say 24 hours, the decoction of 

 the first half will contain much glycogen and little sugar, while 

 that of the second half will contain little glycogen and much 

 sugar ; and this fact may be taken, until the contrary is proved, 

 to shew that the glycogen present in the liver at the moment 

 of death is gradually after death by some action or other con- 

 verted into sugar. 



The action is that of some agency whose activity is destroyed 



