SUGAR FORMATION FROM GLYCOGEN. 399 



livers were removed from the circulation, MINKOWSKI found no sugar 

 in the blood after a few hours. On removing the liver from the 

 circulation by tying all the vessels to and from the organ, the quan- 

 tity of sugar in the blood is not increased (ScHENCK 1 ). An important 

 proof of the possibility of a vital formation of sugar from the liver gly- 

 cogen lies in the fact that we shall learn below of certain poisons and 

 operative changes which may cause an abundant elimination of sugar, 

 but only when the liver contains glycogen. 



A vital formation of sugar from the liver glycogen is now generally 

 accepted. Most investigators consider this as an enzymotic transforma- 

 tion of the glycogen by means of the liver diastase, while certain inves- 

 tigators such as DASTRE, NOEL-PATON, E. CAVAZZANI, McGuiGAN and 

 BROOKS 2 and others explain it by a special activity of the protoplasm. 

 BANG 3 has studied the formation of sugar in frogs' livers, which had not 

 appreciably changed in weight in a RINGER'S solution which was isotonic 

 with the frog blood and which correspondingly had retained their vital 

 properties. This sugar formation does not depend upon a protoplasmic 

 activity but is of an enzymotic nature. It is caused by a diastase, 

 which in Rana esculent a occur in great part in a latent, inactive form 

 due to the inhibitory action of the liver lipoids. Common salt is espe- 

 cially important as an activator for this enzyme. The surviving frog 

 liver is stimulated to a strong sugar production by adrenalin, and this 

 sugar formation is also of an enzymotic nature. The action of the 

 adrenalin consists in an activation of the liver diastase, brought about 

 in various ways. 



The relation of the sugar eliminated in the urine under certain 

 conditions, such as in diabetes mellitus, certain intoxications, lesions 

 of the nervous system, etc., to the glycogen of the liver is also an important 

 question. 



It does not enter into the plan and scope of this book to discuss in 

 detail the various views in regard to glycosuria and diabetes. The 

 appearance of glucose in the urine is a symptom which may have essen- 

 tially different causes, depending upon different circumstances. Only 

 a few of the most important points will be mentioned. 



The blood always contains about the average of 1 p. m., while the 

 urine has in it at most only traces of glucose. When the quantity of 



1 Seegen, Bock, and Hoffmann, see Seegen, 1. c.; Kaufmann, Arch, de Physiol. (5), 

 8; Tangl and Harley, Pfliiger's Arch., 61; Pavy, Journ. of Physiol., 29, Minkowski, 

 Arch. f. exp. Path. u. Pharm., 21; Schenck, Pfliiger's Arch., 57. 



2 See Dastre, Noel-Paton, Cavazzani and their work cited in Pick, Hofmeister's 

 Beitrage, 3, and McGuigan and Brooks, Amer. Journ. of Physiol., 18; R. G. Pearce, 

 ibid., 25. 



3 Bioch. Zeitschr., 49. 



