9 2o METABOLISM. 
been determined. Bicarbonate of soda is stated by Dnfourt 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 invariably 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. "' mM. exptr. etd'anai. path., Paris, 1890, tome ii. p. 424. 
2 Of. Pfliiger, Arch./, d. ges. Physiol., Bonn, 1S8S, Bd. xlii. S. 144. 
3 v. Mering, VerTumdl. f. innere Med., Wiesbaden, 1887, S. 349 ; Ztschr.f. 1:1 in. 
Med., Berlin, 1888, Bd. xiv. S. 405; 1889, Bd. xvi. S. 431. See also on phloridzin 
diabetes, Cremer and Ritter, Ztsehr. f. Biol., Miinchen, 1892, Bd. xviii. S. 459, and Bd. 
xix. S. 256 ; and Praussnitz, ihid. 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./. iwnereMed., 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 (Minkowski, Arch. f. exper. 
Path. n. Pharmahol., 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). 
