922 METABOLISM- 



percentage of sugar in the blood is greatly increased. This seems to point to 

 the fact that phloridzin, besides any action it may have upon the metabolism 

 of carbohydrate in the liver and muscles, increases the permeability of the 

 kidney tubules to sugar, or causes the epithelium of the tubules to be more 

 susceptible to the presence of sugar in the blood, so that the kidney removes 

 sugar from that fluid more rapidly than under normal circumstances, and thus 

 the percentage is even diminished below normal. 1 On the other hand, the 

 diminution in the percentage caused by such removal, even if it were in- 

 appreciable to chemical methods of analysis, might be supposed to excite the 

 sugar-producing tissues to increased activity, thus adding constantly more sugar 

 to the blood, to be again removed by the kidneys, and so on in a vicious circle. 

 On the other hand, Levene 2 has given reasons for believing that the 

 sugar in phloridzin diabetes may be produced in the kidneys, a view which 

 was previously expressed by TJschinsky (quoted by Levene). Thus, after 

 trying the renal blood vessels and then injecting phloridzin, there was no 

 accumulation of sugar in the blood ; indeed, the percentage of sugar in that 

 fluid was, if anything, diminished. Minkowski 3 had previously failed to find 

 an increase above the normal after ablation of the kidneys and injection of 

 phloridzin, and Schabacl 4 obtained analogous results after tying the ureters. 

 Levene also finds that the amount of sugar in the kidneys is increased as the 

 result of giving phloridzin, and that under the same circumstances there is 

 rather more sugar in the blood of the renal vein than in that of the corre- 

 sponding artery. He admits, however, the probability that it is formed in 

 other organs as well as in the kidney. Minkowski 5 has put forward the 

 suggestion that phloridzin becomes split up in the kidney into phloretin and 

 sugar ; the latter becoming eliminated, and the former combining again with 

 sugar in the organism, and then again yielding this to the kidney, and so on. 



Glycogenesis Theory of Bernard. As regards the fate of 

 the carbohydrates of the food, there is no doubt that, whether they 

 inevitably go through the stage of glycogen or not, they ultimately 

 undergo oxidation into carbon dioxide, and removal in the form of this 

 substance and water. The carbohydrate of the food directly increases 

 the amount of carbon dioxide given off, and in proportion to the amount 

 of such food taken. This elimination of carbon dioxide is not immediate, 

 for most of the carbohydrate taken in is in the first instance stored, 

 and only becomes oxidised gradually, as the needs of the organism 

 demand. The view which has been most commonly held with regard to 

 the method of transformation of the stored carbohydrate into the 

 products of its oxidation, originated with Bernard. Having found that 

 the blood of the hepatic vein constantly contains more sugar than 

 the blood of the portal vein, except during the absorption of food, 

 he concluded that the glycogen which he had discovered in the 

 liver, 6 and which is no doubt the chief store of carbohydrate material in 



occur iu cats to which phloridzin had been administered ("Proc. Physiol. Soc.," Nov. 14, 

 1896, Journ. Physiol., Cambridge and London, vol. xx.), and he therefore denies that 

 diiriinished glycsemia is a feature of this form of diabetes. 



1 v. Mering, loc. cit. ; Minkowski, " Untersuch. it. d. Diabetes mellitus," Leipzig, 1893 ; 

 Zuntz, Arch.f. Physiol., Leipzig, 1895, S. 570. 



2 Journ. Physiol., Cambridge and London, 1894-95, vol. xvii. p. 259. 



3 Loc. cit. 



4 Frach., St. Petersburg, 1892, No. 49, quoted from Minkowski. 



5 Op. cit., p. 152. 



6 The fact that sugar is formed in the liver was discovered by Bernard in 1848 

 (Com.pt. rend. Acad. d. sc., Paris, 1848, tome xxvii. pp. 249, 253, 514 ; "Nouvelle fonction 

 du foie, etc.," Paris, 1853), but the substance (glycogen), from which it is produced was 

 not found until 1857 (by Bernard, and also independently by Hensen). For a full list of 

 Bernard's writings on this subject, see " L'ceuvre de Claude Bernard," Paris, 1881. 



