996 
strongly affects the permeability of the kidney to sugar may explain 
two important observations, which have hitherto not been understood. 
One relates to an experiment by UnpbErHILL and CrossEn’), who 
injected into the ear-vena of a rabbit a solution of CaCl, and 
discovered that the hypoglycaemia is attended with glucosuria. The 
most obvious explanation is that we have to deal with a disturbance 
in the equilibrium between Na, K and Ca. 
Secondly it has been known for many years that uranium may 
also cause glucosuria’). Now ZWAARDEMAKER and FEEnstra discovered *) 
that in the RriNGer-fluid which sustains the beating of the frog’s 
heart, the K may be replaced by the likewise radioactive uranium. 
It will appear from the ensuing communication that in the physio- 
logical circulation-fluid of the kidney the K may likewise be replaced 
by an equiradioactive quantity of uranium. Hence it is not assuming 
too much if we consider the uranium-glucosuria as being caused by 
an equilibrium-disturbance occasioned by a disturbance of the normal 
K-percentage. 
It should be noticed that the glucosuria caused by CaCl,- and 
by uranium-injections are the only two of which it may be stated 
with certainty that they are ofarenal kind. Thus with warmblooded 
animals an equilibrium-disturbance in tbe relative cation-percentage 
of the circulating-fluid (here bloodplasm) might also be the cause of 
a modified permeability of the glomerulus epithelium to sugar. 
SUMMARY. 
1. When a RinGer-fluid in which the atoms of K and Ca are 
as 2 to 1 and which contains glucose is transmitted through the 
frog’s kidney at 7°-—10° C, then a comparison of the glucose con- 
centrations of circulating-fluid and ureter-fluid shows us that 0.03 °/, 
of glucose is retained by the kidneys. 
2. If the proportion between K and Ca is somewhat modified, 
the glucose retention will decrease, further modification reducing it 
to 0; in other words the urine contains then as great a concen- 
tration of glucose as the circulating-fluid. 
3. Evidently we have to deal here with a variable permeability 
of the glomerulus epithelium to glucose, not only depending on 
‘1) Unperuitt and Crosson. Americ. Journal of Physiol. 5, p. 321, 1916. Quoted 
from Bane. Der Blutzucker 1913 p. 103. 
2) Porrack, Arch. für exp. Path. u. Pharmakol. 64 p. 415, 1911. See also 
Bana, Der Blutzucker. 
3) ZWAARDEMAKER and FEENSTRA. These reports 1916, 28 April, 27 May, 30 
September. 
