Conductivity of External Solution. 
66 Stiles and Jergensen. — Studies in Permeability. IV. 
rises continually to its maximum value. The surface tension of this solution, 
according to Czapek, is o-86, so that even if there were such a thing as 
a critical concentration it would be lower than 0*5 m., and its surface tension 
higher than 086. Specific toxic action might again be invoked to explain 
this deviation from the o*68 rule, but, according to Czapek, acetone obeys 
the law. 
IV. Aniline and pyridine. 
These two aromatic substances are both basic, and have the same surface 
tension in contact with air. The extent to which their solutions increase 
Time in hours. 
Fig. 13. Exosmosis of electrolytes from potato in solutions of aniline of various concentrations. 
Time in hours. 
Fig. 14. Exosmosis of electrolytes from potato in solutions of pyridine of various concentrations. 
