ANTAGONISM 



169 



upon permeability of eacli substance taken by itself, 

 inasmuch as substances whicb decrease permeability 

 antagonize those which increase it. 



Similar investigations were made upon alkaloids. 

 Antagonism between salts and alkaloids has been reported 



IO0%T 



50% 



O05I 



Fia_. 72. — Curves showing antagonism between NaCl and Na-taurocliolate. The 

 ordinates represent the net electrical resistance of Laminaria agardhii (expressed as per cent. 

 of the control in sea water which is taken as 100%). The abscissae represent the amount 

 of Na-taurocholate added to 1000 o.c. of NaCl 0.52 M. Average of two experiments; 

 probable error of the mean less than 5% of the mean. 



by several authors, the most extensive investigation 

 being that of Eobertson.*" 



The alkaloids studied were nicotine, caffeine and 

 cevadine. They were added in varying amounts to NaCl 

 0.52 M*^, and their effect upon the electrical conductivity 

 of Laminaria was determined. 



The results obtained with nicotine are shown in Fig. 



"For the literature see Robertson, T. B. (1906, 1910, pp. 238, 311). 

 Also SzUcs (1912). 



'^AU the solutions had the same conductivity as sea water. 



