304 NEWTON BALDWIN GREEN ♦ 



of water on the outside of the tissue could only account for a 

 very small fraction of the conductivity. In other words re- 

 sistance is inversely proportional to permeability. 



His next step was to transfer the cylinder to a sodium chloride 

 solution having the same specific conductivity as sea water. 

 After washing the discs thoroughly in this he removed them, 

 drained off the excess and took a series of resistance readings. 

 He found that there was an immediate fall, which up to a certain 

 point was reversible. A solution of calcium chloride of the same 

 specific conductivity as sea water gave an increase in resistance 

 up to a certain point which was reversible. From this he con- 

 cluded that NaCl increases permeability and CaCL decreases it. 

 Later he showed that all monovalent salts act similarly to NaCl 

 and all polyvalent salts similarly to CaCl2. Moreover anaes- 

 thetics added to sea water decreased the permeability. Another 

 significant fact was the effect of a balanced solution of NaCl 

 and CaClo. A solution of this character gave no change in 

 penneability whatsoever, i.e., gave a result smiilar to that m 

 pure sea water. Antagonism would seem to give the only 

 plausible explanation of this phenomenon. In any case it is of 

 prune unportance to detennine the roles played by the different 

 parts of the cells involved in the process, and to determine if 

 possible whether the facts are explainable on a purely physical 

 or chemical basis. 



The results just mentioned were brought to the writer's 

 attention in a course given by Professor Benedict of the Uni- 

 versity of Cincinnati and at his suggestion and under his super- 

 vision, the experiments described below were carried out. The 

 purpose of these experiments was to show if possible the rate of 

 penetration of ions of NaCl and CaClo into cyhnders of certain 

 non-living colloids; and to demonstrate the presence or absence 

 of these phenomena which attended the experunents with 

 living material carried out by Osterhout. In brief the questions 

 which the writer attempted to answer were these : Will a cylinder 

 of colloidal material permit ions of one salt to penetrate faster 

 than those of another? In a mixture of two salts, commonly 

 considered to be antagonistic to one another as regards their 



