562 GLYCOGEN. [Book ii. 



amylolytic ferment 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 compo- 

 sition, 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 

 these when glycogen is present in the liver give, when properly 

 tested with iodine, the characteristic port-wine reaction. 



§ 358. 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 con- 

 tain 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 after death, the amount of glycogen 

 diminishing at the same time. We may infer from this that the 

 glycogen present in the liver at the moment of death is gradually 

 after death by some action or other converted into sugar. 



The action is that of some agency whose activity is destroyed 

 by the temperature of boiling water; hence the directions re- 

 peatedly given above to throw the liver into boiling water. 

 This naturally suggests the presence in the liver of an amylo- 

 lytic ferment. But, not only have attempts to isolate from the 

 liver an amylolytic ferment failed, in the hands of most observers 

 at least, but the exact nature of the sugar which appears shews 

 that the change is not effected by an ordinary amylolytic fer- 

 ment. In the case of the amylolytic ferment of saliva, pan- 

 creatic juice, intestinal juice, and indeed of all other amylolytic 

 animal fluids, the sugar into which starch or glycogen is con- 

 verted is maltose. Now the sugar which appears in the liver 

 after death is dextrose, identical, so far at least as can at present 

 be made out, with ordinary dextrose. We are led therefore to 

 infer that the change of glycogen into suger which appears to 



