993 
Evidently a considerable quantity of sugar is retained as long as 
the dilution of the serum is not an 8-fold one (0.17—0.086, 0.21— 
0.11, 0.21—0.105, 0.14--0.03, 0.14—0.028). 
In stronger dilutions the retention of sugar grows less, and in 
an 8-fold dilution it is 0. 
It was now attempted to trace the cause of this rather abrupt 
turning point, but in the midst of this somewhat elaborate investi- 
gation, which we shall not discuss here, the stock of Rinerre-fluid. 
gave out, and a fresh quantity bad to be prepared. It soon became 
evident now that the retention power of the kidney for glucose in 
the serum-RINGER-mixtures was entirely different from what it had 
been in the previous experiments. 
The possibility had to be taken into account that the Rinerr-fluid 
was not identical with the one formerly used. Was the Ca-percentage 
different perhaps? We often read of a CaCl,-solution of a given 
concentration without there being added if it has been made of 
anhydrous CaCl, or of CaCl, 6 aq. It was indeed found that an 
addition of some CaCl, strongly affected the glucose-excretion, for 
now the concentration of the ureter fluid was equal to that of the 
transmission-fluid. This observation, confirmed by parallel-experiments, 
induced us to determine whether the circulation of the new serumless 
RiNGER-solution would cause all glucose to be diffused, as had been 
the case with the original Rincer-fluid. 
To our surprise we discovered that when the new RiNGer-fluid 
was transmitted, glucose was retained by the kidneys. 
Under these circumstances it became necessary to institute a systematic 
investigation of the way in which a change in the composition of 
the Rrnerr-fluid affects the permeability of the kidney. The present 
paper confines itself to this investigation. We shall afterwards revert 
to the effect of serum being added. 
4. Change in the proportion of the quantities of K and Ca 
in the Rincer-fluid. 
349 Series of Experiments. 
It appears from the following table that only the amount of 
CaCl, was modified, the KCl remaining the same. 
Each of the four experiments was repeated 3 times with exactly 
the same results. 
Evidently no glucose is retained if a solution of CaCl, 0,005 °/, 
is used; when however, the solution contains 0,0075 °/,, 0.095—0.065= 
