1918] Waynick: Antagonism and Cell Permeability 153 



the root growth, or vice versa. As will be noted, the percentages 

 of calcium and magnesium found are low. in fact below the control 

 in every case. Whether or not ferric sulphate would be stimulating 

 in still higher concentrations is not known, but it is probable that the 

 limit of stimulation was reached, since the roots show a ma rk.nl de- 

 crease in growth in the highest concentration used. The percentage 

 of iron found js comparatively high. The reason for this increased 

 growth is evidently bound up with the presence of the ferric salt, 

 lmt no idea of the nature of its action can be given. It is very evi- 

 dent from the present data, however, that the amounts of the elements 

 present in the plants were low. 



In table 23 the results with zinc sulphate alone are reported. 

 There is no stimulation or no antagonism between zinc sulphate ami 

 the other constituents of the solution evident in any concentration. 

 As growth decreases magnesium was found present in larger amounts 

 than in the cultures in which growth was more nearly normal. The 

 percentage of calcium remains very much the same in the tops and 

 decreases rapidly in the roots with decreasing growth. Here we have 

 a suggestion of a relationship between zinc and calcium as has already 

 been referred to in the case of iron. It can only be stated, however, 

 that the results as regards calcium penetration are exceptional in the 

 light of the results in other series previously referred to. 



Turning to table 24, in which the results with zinc sulphate and 

 ferric sulphate are given, there is a marked contrast on the one hand 

 with series 20 in which zinc sulphate and copper sulphate were used. 

 and on the other hand with the preceding series in which zinc sulphate 

 alone was used. In this series there is marked antagonism shown be- 

 tween the salts employed. This is true for both tops and roots, but 

 the most marked increase in both does not occur in the same culture. 

 The marked increase in growth of the tops evident in culture 4 is 

 accompanied by a decrease in the percentages of calcium and mag- 

 nesium present in the tops but not in the coots. The percentage of 

 magnesium in the roots increases with decreased growth throughout 

 the series. The calcium in the tops is low and abnormally so in the 

 roots. Growth is good throughout the series and in culture 4 is in- 

 creased about 50 per cent above the control. This result would hardly 

 be expected from the decreases recorded where zinc sulphate was used 

 alone in the preceding series. The percentage of iron varies some- 

 what, but does not increase or decrease with any regularity in any 

 one direction. Attention is again called to the low calcium content, 

 especially of the roots. 



