1918] Waynick: Antagonism and Cell Permeability 1">1 



several following, the concentrations of both salts added increase, that 

 is, both increasing but bearing the same ratio between the two. 

 There is an increase of approximately 100 per cent in the dry weight 

 of culture 2 over cultures 1 and 3. The low absorption of culture 2 

 as related to 1 and 3 is evident. There is a marked decrease in the 

 percentages of calcium and magnesium found in the plants grown in 

 culture 5, in which the dry weight of the plants was also low. A1 this 

 second point, however, iron and copper were found in larger amounts 

 than at any other concentration used. As in the previous series the 

 percentage of calcium in the tops does not seem to parallel that in the 

 roots or of magnesium in either roots or tops. A similar relationship 

 was brought out in the previous series in which copper chloride alone 

 was used. No apparent precipitation took place upon the addition of 

 iron in the concentrations given, but a precipitate composed of ferric 

 phosphate was present at the time of harvesting. It is possible that 

 double salts of copper or iron with calcium or magnesium and. for 

 instance, the phosphate ion were formed at the higher concentrations. 

 Their complexes may not be taken up by the plants and hence actual 

 starvation as far as these elements are concerned, may be responsible 

 for the low amounts found in the plants. Such a condition contrasts 

 directly with one in which there is low permeability due to antagonistic 

 effects between the ions in the solution. 



In table 18 mercuric chloride was used with copper chloride, since 

 it was desired to determine the effects produced by the addition of 

 two highly toxic salts to the nutrient solution. The results with mer- 

 curic chloride alone are given in table 26. They are somewhat irregu- 

 lar, but there can be no doubt of the correlation between the quanti- 

 tative presence of calcium and magnesium in the tops, of magnesium 

 in the roots, and growth. There is evidence of a distinct antagonistic 

 action between copper and mercuric chlorides both from the stand- 

 point of growth and that of absorption. The root growth was very 

 limited. The percentage of calcium and magnesium in the roots was 

 very high; high enough to account for the decreased growth by itself 

 if we use the results of other series in interpreting this one. Not 

 enough iron was present in any culture to permit of its determination. 



Considering the most common salt of copper used in solution cul- 

 tures and soil work, the results as given in table l!» are especially 

 noteworthy. The concentrations of the sulphate used are low. Dis- 

 tinct evidence of the toxic effects of the salt, together with only slight 

 decrease in growth in culture 4 of the series is shown. High percent- 



