1918] Waynick: Antagonism and Cell Permeability L49 



ing concentrations of aluminum chloride arc shown in tabic 11. In 

 general the toxic effects of the two salts seem to be additive, that is. 

 the growth in this series in which two salts arc present together is 

 less than in the preceding series where aluminum chloride was used 

 alone. The decrease is not great from the standpoint of total weight, 

 but proportionately is very considerable, amounting to from 33 per 

 cent to 100 per cent in the various concentrations employed. The 

 percentage of magnesium in the two series is about the same. The 

 amount of calcium absorbed, on the other hand, is increased over 300 

 per cent and remains constant throughout. The total absorption with 

 respect to calcium and magnesium, at least, is uniformly high. This 

 fact is reflected in the increase in the percentage of ash over that of 

 the control. In the next series ad factors are the same except th.it 

 magnesium chloride was used instead of calcium chloride, there bcim: 

 no difference whatever in partial or total concentration. The antag- 

 onism shown between magnesium chloride and aluminum chloride in 

 culture 4 is very marked, and correlated with the increased growth is 

 the marked decrease in the percentage of both magnesium and cal- 

 cium found in tops and roots. The percentage of magnesium found 

 in the plants is not proportional to the concentration in the solution 

 as was true with calcium chloride. An interesting case of the in- 

 creased absorption of one element with a decrease in the other is well 

 illustrated in the case of culture 6 of this series. Such a relationship 

 has been noted previously, but is apparently of no direct importance 

 from the standpoint of growth. 



Ferric chloride, a second trivalent salt, was used in the nutrient 

 solution in the concentration shown in table 18. In the concentration 

 employed, growth is nearly normal and absorption is very nearly the 

 same as with plants in the control cultures, except in the case of cal- 

 cium. The decrease in some instances in the percentage of calcium 

 found, as iron increases in the nutrient solution, is notable, and will 

 be referred to later in connection with the action of ferric and zinc 

 sulphates. 



The effects of adding .20 M. calcium chloride together with vari- 

 ous concentrations of ferric chloride, are given in table 14. The 

 growth of roots and top parallel each other closely. .Marked toxic 

 effects are evident in certain combinations as in cultures :! and 7. 

 The percentage of calcium found in both roots and tops is high in 

 plants grown in the same cultures. The magnesium presenl in 

 the tops shows the same relationships as the calcium, although the 



