995 
glucose 0.09°/,. To our surprise little or no glucose was retained 
now. Then the possibility was debated whether perhaps the amount 
of Na might tell upon the results. The answer is supplied by the 
following table. 
0, NaCl | %g NaHCO; 9/9 KCI | % CaCl, |- rs bet nin 
| Circul. fl, Urine 
0.7 0.02 0.01 0.0075 0.09 0.09 
Dr 0.02 0.01 0.010 0.102 | 0.085 
O27 0.02 0.01 0.012 0.105 0.085 
0.7 0.02 0.01 0.0075 0.085 0.085 
0.6 0.02 0.01 0.0075 0.085 0.060 
0.6 0.02 0.01 0.0075 0.010 0.070 
0.6 0.02 0.01 0.005 0.09 0.070 
0.6 0.02 0.01 0.0025 0.085 0.075 
0.6 0.02 0.01 0.010 0.12 0.115 
Obviously these results differ from those in the preceding table 
in which KCl : CaCl, = 4: 3 and where 0.03 °/, of glucose was 
retained. Something indeed is retained when we use the new frogs, 
but not 0.03 °/,. 0.02 °/, is retained when we use KCl: CaCl, = 
ORT. 
Why did the new consignment of frogs behave in a way different 
from the first? The temperature at which they were kept might be 
the cause. Jt was + 8° C.; formerly it had been higher. That the 
difference is indeed due to the temperature is made manifest by the 
fact that, in order to obtain the same results some CaCl, must be 
added to the circulating fluid when the kidney is cooled down by 
ice. If we wish to maintain the proportion KCl: CaCl, = 4:3, then 
the NaCl must be reduced from 0.7 to 0.6 °/,. 
It follows that with every condition of the glomerulus epithelium 
must correspond, if it is to keep back a maximum amount of glucose, 
a certain proportion between Na, K and Ca. 
It is not improbable that the anions too play a part in the equi- 
librium, but at any rate one gets an impression that the proportion 
of cations preponderates. 
The fact that a disturbance in the equilibrium of the cations 
