72 LECTURE IV. 



however, has shown that this sugar formation will also take place in 

 chloroform water. Since aqueous solutions of chloroform prevent proto- 

 plasmic action including the action of micro-organisms, this experi- 

 ment proves that the formation of sugar from glycogen is not due to the 

 action of bacteria, and further that the liver cells themselves are not the 

 cause, but that the hydrolysis of glycogen is to be traced to the action of 

 a soluble ferment. ' Salkowski clearly established this important fact by 

 means of the following experiment: He removed the liver from a rabbit 

 which had taken into its stomach seventeen hours before death ten grams 

 of cane-sugar dissolved in water. After taking out the gall bladder and 

 the large bile ducts, the liver was cut up into fine pieces and triturated. 

 Two portions of the same weight of liver-pulp were taken, one of which 

 was placed directly in a bottle filled with chloroform water; the other 

 portion was boiled in water first, and then treated with the same amount 

 of chloroform water. After sixty-eight hours' digestion, the glycogen and 

 sugar were determined in each of the extracts. The first extract showed 

 a large amount of sugar and no glycogen, whereas the extract of the 

 boiled liver contained considerable glycogen and only very little sugar. 

 In the first experiment there were found 48.28 grams of sugar; in the second, 

 3.65 grams. 



As we have seen, the glycogen content of the liver stands in a definite 

 relation to that of the muscles. After the muscles have performed hard 

 work, we find that not only does the glycogen in them disappear, but that 

 in the liver as well. This leads us to believe that the liver serves as a 

 central storage place which is capable of feeding all the other stores in the 

 organism. The transfer of the liver-glycogen takes place by means of 

 the blood, and in the form of d-glucose as we have seen. Now the organism 

 strives to a remarkable degree, even during starvation, to maintain a 

 constant amount of sugar in the blood. If the glycogen in the muscles is 

 used up, the muscle cells then strive to form glycogen from the sugar in 

 the blood. This would cause a diminution in the sugar content of the 

 blood, except for the fact that as soon as this sugar is removed, then hepatic 

 glycogen is decomposed into d-glucose and removed by the blood. 1 It 

 has been stated that the higher products of the hydrolysis of glycogen, 

 namely dextrin and maltose, are likewise transported by the blood; but 

 how far such observations are correct, or what the extent to which this takes 

 place, cannot be decided at present. At all events, such statements have 



1 The assumption made by J. Seegen (Die Zuckerbildung im Tierkorper, ihr Umfang 

 und ihre Bedeutung, Berlin, 1890, and Studien iiber Stoffwechsel im Tierkorper, Berlin, 

 1887), that blood-sugar is formed from proteins in the nourishment, and that on the 

 other hand the liver-glycogen originates from the fats, is not supported by the facts. 

 Cf. R. Bohm and F. A. Hoffmann: Pfliiger's Arch. 23, 205 (1880). H. Girard: Pfliiger's 

 Archiv. 41, 294 (1887). E. Cavazzani: Arch. Anat. Physiol. 639 (1898). 



