Fig. 2. Antagonism curve showing the effect of NaCl o.i M+CaCU 0.07 M and of 
mixtures of these upon the respiration of Elodea canadensis after an exposure of one houf. 
The abscissae represent molecular proportions. Each point represents the average of 3 
or more experiments; probable error of the mean, less than 4 percent of the mean (except 
in one case where it amounts to less than 6 percent). 
