390 THE LIVER. 



liver was not essentially changed which speaks against a simple storage 

 of food protein. 



Glycogen and its Formation. 



Glycogen was first discovered by BERNARD. It is a carbohydrate 

 closely related to the starches or dextrins, with the general formula 

 mCCoHioOs). Its molecular weight is unknown, but seems to be very 

 large (GATIN-GRUZEWSKA and v. KNAFFL-LENZ 1 ). The largest quan- 

 tities are found in the liver of adult animals, and smaller quantities 

 in the muscles (BERNARD, NASSE). It is found in very small quantities 

 in nearly all tissues of the animal body. Its occurrence in lymphoid 

 cells, blood, and pus has been mentioned in a previous chapter, and it 

 seems to be a regular constituent of all cells capable of development. 

 Glycogen was first shown to exist in embryonic tissues by BERNARD 

 and KUHNE, and it seems on the whole to be a constituent of tissues 

 in which a rapid cell formation and cell development are taking place. 

 It is also present in rapidly forming pathological tumors (HOPPE-SEYLER) . 

 Some animals, as certain mussels (Bizio), Tsenia and Ascaridse (WEIN- 

 LAND 2 ), are very rich in glycogen. Glycogen also occurs in the vegetable- 

 kingdom, especially in many fungi. 



The quantity of glycogen in the liver, as also in the muscles, depends 

 essentially upon the food. In starvation it disappears almost com- 

 pletely after a short time, but more rapidly in small than in large animals, 

 and it disappears earlier from the liver than from the muscles. As 

 shown by C. VOIT, KULZ and especially by PrLUGER, 3 it never entirely 

 disappears in starvation, as a re-formation of glycogen always takes 

 place. After partaking of food, especially such as is rich in carbo- 

 hydrates, the liver becomes rich again in glycogen, the greatest incre- 

 ment occurring 14 to 16 hours after eating (KULZ). The quantity of 

 liver-glycogen may amount to 120-160 p. m. after partaking of large 

 quantities of carbohydrates, and in dogs which had been especially 

 fed for glycogen SCHONDORFF and GATIN-GRUZEWSKA found still higher 

 results, even more- than 180 p. m. Ordinarily it is considerably less, 

 namely, 12-30 to 40 p. m. The highest amount of glycogen in the liver 

 thus far observed was 201.6 p. m., found by MANGOLD 4 in the frog. The 



1 Gatin-Gruzewska, Pfliiger's Arch., 103; v. Knaffl-Lenz, Zeitschr. f. physiol. Chem., 

 46. 



2 Zeitschr. f. Biologie, 41. The extensive literature on glycogen may be found in 

 E. Pfliiger, Glykogen, 2. Aufl., Bonn, 1905; and in Cremer, " Physiol. des Glykogens," 

 in Ergebnisse der Physiologic, 1, Abt. 1. In the following pages we shall refer to these 

 works. 



3 Pfliiger's Arch., 119, which contains the literature. 



4 Ibid., 121. 



