312 CHEMICAL CONSTITUENTS OF THE LIVER-CELLS. 



and (2) the proteids, including gelatin. If the proteids are a source 

 of glycogen, it must result from a non-nitrogenous derivative of them. 



Pfluger considers the formation of glycogen from albumin a synthetic process. 

 The molecular group CH 2 , found in albumin, as well as in the fatty acids, must 

 be transformed by oxidation into CHOH. The cells taking part in the formative 

 process may, however, also utilize this group CHOH wherever it is found already 

 prepared, as in sugar or in glycerin. 



Also fats (olive-oil), glycerin, taurin and glycin (the latter through decomposi- 

 tion into glycogen and urea) , have been designated as the source of glycogen. 



In rabbits, the production of glycogen is increased by the administration of 

 asparagin, ammonium carbonate or urea. The excessive production of acid in 

 cases of diabetes, demonstrated by Stadelmann, fixes the ammonia and thus 

 materially diminishes the production of glycogen. 



Ligation of the common bile-duct results in diminution of the glycogen in 

 the liver. The liver after this operation appears to have lost the property of form- 

 ing glycogen from suitable material brought to it. Also ligation of the hepatic 

 artery renders the liver free from glycogen. After excluding the portal circulation 

 the amount of sugar contained in the blood decreases. With reference to the occur- 

 rence of glycogen elsewhere reference may be made to p. 466. 



If large amounts of starch, grape-sugar, cane-sugar, levulose and 

 maltose are added to the proteids of the food, the amount of glycogen 

 in the liver is greatly increased, while on a pure albuminous or fatty 

 diet it is considerably decreased ; the state of hunger may cause it to dis- 

 appear entirely. Injection of grape-sugar or of glycerin into a mesen- 

 teric vein of a fasting rabbit causes the appearance of glycogen in a 

 liver previously free from it. 



The living liver-cell is capable of producing glycogen in considerable quantities 

 only from the two kinds of sugar capable of direct fermentation, namely dextrose 

 and levulose. The non-fermentable sugars are not converted into glycogen, and 

 cane-sugar and maltose only in so far as they are transformed in the intestine into 

 dextrose. As the infant consumes milk-sugar, it must form glycogen from albu- 

 min. 



Forced muscular movement rapidly renders the liver of the dog free from 

 glycogen. Reduction of temperature .diminishes the amount of glycogen in the 

 liver. The rigid liver after death contains dextrin and grape-sugar. Glycogen 

 is also present in the liver for a considerable time after death, as well as in the 

 muscles. 



Under normal conditions, the glycogen in the liver is gradually 

 transformed in small amounts into grape-sugar. The amount of sugar 

 normally present in the blood is from 0.5 to i in 1000. The blood in 

 the hepatic veins may contain somewhat more. Increased transforma- 

 tion into sugar occurs only in connection with marked circulatory dis- 

 turbances in the liver, as a result of which the blood of the hepatic veins 

 comes to contain a larger amount of sugar. The glycogen undergoes 

 this transformation, likewise, soon after death, when the liver is always 

 found to contain a larger amount of sugar and a smaller amount of gly- 

 cogen. 



The active ferment necessary for this process can be obtained from 

 an extract of the liver-cells, by the method employed to obtain ptyalin. 

 Nevertheless, it is said not to be formed in the liver-cells, but only 

 reaches the liver to be quickly stored up, through the blood, within 

 which the ferment is always formed with rapidity so soon as the move- 

 ment of the blood undergoes marked disturbance. This transforming 

 ferment develops also as a result of the solution of red blood-corpuscles ; 

 and as a constant slight destruction of red blood-corpuscles must surely 

 be assumed to take place within the liver, a source is thus provided 



