W. J. V. OSTERHOUT 519 



not successful in the case of nicotine, owing to the formation of a 

 visible precipitate, which was apparently due to the presence of cal- 

 cium and magnesium in the sea water. In the case of caffeine (0.01 

 to 0.04 m) and of cevadine sulfate^ (0.0006 to 0.0025 m) a distinct de- 

 crease in permeability was found (as shown by the rise in resistance) ; 

 this was followed by an increase. In this respect they resemble 

 CaCl2 which also produces a decrease in permeability when added to 

 sea water. The same is true of typical anesthetics, such as ether and 

 chloroform.^ 



The idea that substances which have opposite effects on per- 

 meability can antagonize each other seems to apply to alkaloids as 

 well as to salts. 



SUMMARY, 



Certain alkaloids which decrease permeabihty are able to antag- 

 onize NaCl. In this respect they resemble salts which decrease 

 permeability, for it has been shown that such salts antagonize NaCl. 



^ This is regarded as two molecules of cevadine united to one molecule of 

 H2SO4. It was purchased from Merck under the name of veratrine sulfate 



(C32H49N09)o.HoS04. 



SQsterhout, W. J. V., Bot. Gaz., 1916, Ixi, 148. 



