991 
containing sugar, to which serum had been added, produced an 
artificial urine free from sugar, then it was, as we thought, con- 
clusively shown that the serum contains a substance retaining sugar 
in a form which cannot diffuse through the glomerulus epithelium, 
and then further researches might be made as to the nature of 
this substance. 
Before entering upon the description of the experiments we wish 
te make a few observations of a technical nature. 
Some remarks of a technical kind. 
The experiments were exclusively carried out with frogs, viz. 
with large male specimens of the Rhine frog. The spinal marrow 
was destroyed with a needle, and all organs except kidneys, testicles 
and bladder were removed at once. Then a thin injection-needle 
was inserted into the aorta communis and a canula into each ureter. 
The fluid which circulates through the vascular system must be 
amply provided with oxygen. The pressure amounted to 60—80 
centimetres of water. In this way from 300 to 800 cubic e.m. of 
fluid flows through the kidneys per hour. The amount of fluid 
passing through the ureter is 0.5 e.c. or less. This fluid must be 
looked upon as a glomerulus product, for if at the same pressure 
fluid is transmitted through the vena Jacobsonii, then no fluid is 
secreted in the ureters. At a higher pressure some fluid is formed 
but very slowly. 
The glucose-percentage of the urine is not affected by the vena 
Jacobsonii being tied off. This makes it probable that the kidney 
ducts have little to do with the glucose motion. 
The glucose-determination of transcirculating-fluid and kidney-pro- 
duct was carried out by means of tbe excellent method of I. Bane '). 
It enables one to determine the glucose-percentage in 0.1 c.c. of 
fluid to within 0.006 °/,. 
2. The permeability of the frog's kidney to glucose which 
has been dissolved in Rinerr-fluid. 
re Series, of Hx pera ments. 
As we said before the fundamental problem to be solved in the 
first place was whether at a transmission of RINGER-fluid containing 
1) J. Bana. Methoden zur Mikrobestimmung einiger Blutbestandteile. Wiesbaden, 
J. F. BERGMANN. 1916. 
; 63* 
