920 METABOLISM. 



been determined. Bicarbonate of soda is stated by Dufourt to have the effect 

 of increasing the amount of glycogen in the liver. Dufourt's experiments 

 were made upon dogs on a flesh diet after a period of fasting. 1 



Glycogen becomes formed in the embryo chick in considerable 

 amount, although there is very little glycogen or carbohydrate at all 

 in the egg. Here also it must in all probability be formed from proteid. 

 Glycogen can only be supposed to be produced from proteids in the 

 animal body by a process of synthesis, preceded by a breaking down of 

 the proteid molecule. 2 It is highly probable that dextrose is a stage in 

 the course of such synthesis ; and since dextrose is constantly found in 

 the blood, even in prolonged inanition, it may well be inquired whether 

 the carbohydrate of the body is inariably converted into glycogen, 

 prior to being employed by the tissues for the production of energy. 

 Under certain circumstances it appears clear that the synthesis of 

 carbohydrate never passes beyond the stage of dextrose. Thus, in the 

 diabetes produced by successive doses of phloridzin there may be no 

 glycogen whatever in the liver and muscles, and yet within the proteid- 

 fed and in the fasting animal large quantities of dextrose are formed 

 and eliminated with the urine. 



Phloridzin is a glucoside obtained from the root-bark of certain 

 trees (apple and cherry), but it does not act by virtue of its glucose 

 group, for the same action is got by the employment of the non-glucoside 

 phloretin which is obtained from phloridzin. If injected under the 

 skin, or taken into the alimentary canal, either phloridzin or phloretin 

 produces within a very short time the appearance of sugar in the urine, 

 and this appearance of sugar in the urine is accompanied by a diminution 

 of the liver glycogen. 3 The glycogen in the liver does not, however, 

 completely disappear as the result of a single dose of phloridzin ; both in 

 that organ and in the muscles a certain amount remains, but if a second 

 dose of phloridzin is given, glycosuria is again produced, and by repeating 

 the administration once or twice the glycogen can be completely removed 

 from the liver. Each successive dose of phloridzin will, however, cause 

 a fresh appearance of sugar in the urine even after complete removal of 

 glycogen from the liver, which shows that, although part of the sugar 

 which has appeared in consequence of the action of phloridzin may have 

 been produced from the glycogen in the liver, a part must be produced 

 in some other way. As by the employment of successive doses of this 

 drug all the appreciable glycogen in the body can be got rid of, 4 it is 

 almost certain that the sugar which then appears is derived from the 

 metabolism of proteid ; and this is rendered the more likely since it is 



1 Arch, de med. exper. ef, d'anat. path., Paris, 1890, tome ii. p. 424. 



2 Cf. Pfiiiger, Arch.f. d. ges. Phyxiol., Bonn, 1888, Bd. xlii. S. 144. 



a v. Mering, Verhandl. d. Cong. f. innere Med. , Wiesbaden, 1887, S. 349 ; Ztschr.f. Uin. 

 Med., Berlin, 1888, Bd. xiv. S. 405 ; 1889, Bd. xvi. S. 431. See also on phloridzin 

 diabetes, Cremer and Ritter, Ztschr. f. BioL, Miinchen, 1892, Bd. xviii. S. 459, and Bd. 

 xix. S. 256 ; and Praussnitz, ibid. S. 168. 



4 Kiilz and Wright (Ztschr. f. BioL, Miinchen, 1891, Bd. xxvii.) have shown that the 

 glycogen is not so readily got rid of as v. Mering supposed, and that as a matter of fact 

 there may still have been some glycogen left in the animals employed by v. Mering. These 

 authors state that phloridzin does not produce glycosuria in frogs. It did, however, 

 produce glycosuria in birds (v. Mering, Verhandl. d. Cong. f. innere Med., Wiesbaden, 1887), 

 in which pancreatic extirpation failed to cause glycosuria ; it also increases the amount of 

 sugar in the urine of animals suffering from pancreatic diabetes (Minkowsld, Arch. f. exper. 

 Path. u. PharmakoL, Leipzig, 1893, Bd. xxxi. S. 148) ; and, further, Cremer has obtained 

 phloridzin diabetes in frogs by taking special measures to ensure the action of the drug 

 (Ztschr. f. BioL, Miinchen, 1892-3, Bd. xxix. S. 175). 



