ANTAGONISM 



171 



half dead). It is evident that nicotine antagonizes the 

 action of NaCl by inhibiting the fall of resistance which 

 occurs in pure NaCl. The upper curve (2 hours) shows 

 even more pronounced antagonism. 



The results with caffeine (Fig. 74) are similar except 

 that the curve does not fall as rapidly with increasing 



8oi% 



.06 n 



Fig. 74.— Curves showing antagonism between NaCl and caffeine. Ordinates represent net 

 electrical resistance of Laminaria agardhii (expressed as per cent, of the normal) ; absciss&e 

 represent concentrations of caffeine added to 0.52 M NaCI. The resistance of the control 

 at 18K hours was 96%. Average of two experiments; probable error of the mean less than 



5% of the mean. 



concentrations of alkaloid. With cevadine (Fig. 75) the 

 curve falls much more rapidly, the maximum being in the 

 neighborhood of 0.005 M cevadine sulfate. Here death 



