191S] Wayniek: Antagonism and Cell Permeability 147 



with its sharp decline. The low percentage of magnesium is of interest 

 since the concentration of the culture solution was uniformly high 

 with respect to this ion. 



It is striking that there is a marked decrease in the growth (it* roots 

 at the concentration which gave the best growth of tops, and further 

 that the percentage of calcium in the tops and magnesium in the 

 roots parallel this decrease in the growth of the roots. A comparison 

 of the results obtained with magnesium sulphate as againsl those with 

 magnesium chloride is reserved for later discussion. 



In table 7 we have an opportunity to compare indirectly anion 

 effects, or possibly the effects of combinations of the same kation with 

 different anions. From preliminary results it seemed advisable to use 

 .15 M. magnesium sulphate in this series instead of .18 M. as used in 

 the preceding series, so that the concentration of magnesium ion is 

 not equivalent in the two series. A solution containing magnesium 

 sulphate .15 M. plus calcium nitrate .08 M. proved highly toxic, while 

 a solution containing calcium chloride of the same concentration as 

 the nitrate in the above solution supported normal growth. It is 

 possible that the difference is due to the toxic action of the nitrate ion 

 ou the plant directly. Tottingham has shown that the total ionization 

 of a nutrient solution was decreased 10 per cent below the theoretical 

 by the addition of calcium nitrate in low concentrations. It is pos- 

 sible that the ionization of some other salt is repressed so that there 

 is an actual lack of some ion necessary for growth. The percentage 

 of calcium found was not high enough in any case to account for the 

 toxic effects shown. Magnesium was found in extremely large 

 amounts, 9.20 per cent in the case of culture 6, the largest percentage 

 recorded in any culture studied. Unfortunately the series in which 

 the toxic effects of calcium nitrate alone were studied was lost, so it 

 cannot be reported here. 



Potassium chloride was the only monovalent salt studied, and the 

 results are given in tables 8 and 9. The growth shown in the various 

 concentrations of potassium chloride used was approximately the 

 same as that found when magnesium sulphate was used alone. The 

 increase in the percentage of ash, as far as the tops are concerned in 

 table 8 is very striking. The percentage of calcium found in the tops 

 and of magnesium found in the roots remains practically constant 

 throughout. The amount of potassium absorbed increases as the con- 

 centration of potassium chloride in the solution increases and in- 

 versely as the growth of the plants. The toxic effects due to the 



