669 



brought to light that, apart from other factors, the permeability of 

 the glomerulus membrane is, to a high degree, dependent on the 

 OaCl, percentage of the transmission-fluid and further that this 

 permeability is also affected by the KCl and NaCl concentrations. 



We subjoin a series of experiments which demonstrates the effect 

 of calcium and which was not published in our tirst paper. (See 

 Table I, preceding page). 



This series of experiments was carried out in February — March 

 1917.^) 



Evidently glucose-retention took place only when the CaCl,- 

 concenlration varied between 0.01 27o and 0.01 67o. that is to say 

 the Oa-concentration has its strict limits, and admits of but little 

 variation. Of the ± 0.1 7o of glucose in the transmission fluid at 

 most 0.037o of glucose was retained. 



To determine the effect of Potassium in the transmission-fluid the 

 KCl concentration was modified while the NaCl, NaHCOg and CaCl, 

 remained the same. Increasing quantities of KCl were therefore added 

 to the fluid composed of NaCl 0.67,, NaHCO, 0.027,, OaCl, . 6 aq. 



TABLE II. 

 Effect of the KCl concentration in the Ringer fluid. Experiments of March 1917. 



^) It is desirable to know wheliier summer- or winter frogs are used for the 

 experiments. Of. Verslagen van Jan. 27, 1917 p. 949. 



