THE LIVER. 403 



Jacoby. To the presence of this latter autolytic phenomena, which 

 have been described by Salkowski and his pupils, are possibly due. 

 A urea-forming enzyme also is said to occur in the liver, but its 

 existence has not as yet been satisfactorily demonstrated. 



Glycogen. Amount. The amount of glycogen which occurs in 

 the liver is primarily dependent upon the state of nutrition of the 

 animal and the amount of exercise that is taken. This is apparent 

 from the fact that it is constantly consumed during the activity of the 

 muscle-tissue more especially, but is also utilized in the regeneration 

 of all cellular elements of the body. During starvation it rapidly 

 disappears, but it is also rapidly formed if carbohydrates are then 

 ingested. Maximal amounts, according to Kiilz, are found after 

 from fourteen to sixteen hours following the administration of food. 

 It has been calculated that in the liver of man 150 grammes can be 

 stored at one time. This would correspond to about 10 per cent, 

 for an organ weighing 1500 grammes. In dogs which have been 

 fed on potatoes and bread Pavy claims to have found as much as 17 

 per cent. After death the transformation of glycogen into glucose 

 continues as in the case of muscle-tissue, and in order to ascertain 

 the exact amount which was present during life it is hence necessary 

 to remove the organ at once and to prevent the further inversion of 

 the material, by the living protoplasm or the contained ferments, by 

 placing the tissue in boiling water. 



Properties. The pure substance represents a white, amorphous 

 powder, which is both odorless and tasteless. In water it forms an 

 opalescent solution, from which it can be precipitated by the addi- 

 tion of alcohol, after adding a little sodium chloride, or by means 

 of lead subacetate. The substance is dextrorotatory. The specific 

 degree of rotation, however, seems to be influenced by various 

 factors. In pure solution it is given as + 196.63. It does not 

 reduce Fehling's solution, but can maintain ctipric hydroxide in 

 solution. After the addition of a little sodium chloride its solutions 

 are colored red by treating with iodine. With benzoyl chloride, in 

 the presence of sodium hydrate, it gives a granular precipitate of 

 benzoyl-glycogen. On boiling with dilute mineral acids it is trans- 

 formed into glucose. Ferments invert it to maltose or glucose, 

 according to the nature of the enzymes at work. 



Isolation and Quantitative Estimation. The perfectly fresh liver, 

 immediately after removal from the animal, is placed in boiling 

 water and divided into small pieces. After boiling for a few 

 minutes these are removed, ground to a pulp with sand or pulverized 

 glass, and then boiled in a 1 per cent, solution of sodium hydrate, 

 using 400 c.c. for every 100 grammes of tissue. With liver-tissue 

 two to three hours suffice, while with muscle-tissue it is best to boil 

 for from four to eight hours. Care must be had during this process 

 that the concentration of the alkali does not exceed 2 per cent. ; to 

 this end water is added from time to time. The alkaline extract 

 after filtration is then united with the watery solution first obtained, 



