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 Uschinsky (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 Schabad 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 in cats to which phloridzin had heen administered ("Proc. Physiol. Soc," Nov. 14, 
1896, Joum. Physiol., Cambridge and London, vol. xx.), and he therefore denies that 
diminished glyctemia is a feature of this form of diabetes. 
1 v. Mering, loc. tit. ; Minkowski, " Untersuch. ii. d. Diabetes mellitus," Leipzig, 1893 ; 
Zuntz, Arch.f. Physiol., Leipzig, 1895, S. 570. 
'■> Jaurn. Physiol., Cambridge and London, 1894-95, vol. xvii. p. 259. 
3 Loc. cit. 
4 Vrach., St. Petersburg, 1892, No. 49, quoted from Minkowski. 
5 Of. cit., p. 152. 
6 The fact that sugar is formed in the liver was discovered by Bernard in 1848 
{Compt. rend. Acad. d. se., 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 Heusen). For a full list of 
Bernard's writings on this subject, see " L'ceuvre de Claude Bernard," Paris, 1881. 
