146 University of California Publications in Agricultural Sciences [Vol.3 



is higher than in the cultures of slightly higher or lower concentra- 

 tions. No explanation of the narrow ratio between these two ele- 

 ments at this point can be offered. It is of interest to note the very 

 great increase in the amounts of calcium and magnesium found in 

 the plants grown in concentrations of .20 M. calcium chloride alone. 

 While magnesium chloride is constant throughout the series, the 

 amount of magnesium does not increase proportionately to that of 

 calcium. 



A still higher concentration of magnesium chloride was used in 

 the series reported in table 4. The percentage of magnesium found 

 in the roots is very high and would indicate that it was not entirely 

 removed from the roots by washing. In general the percentages of 

 calcium and magnesium found are high, the calcium content increas- 

 ing as the concentration of calcium chloride present in the culture, 

 but not proportionately. Magnesium is lower at the greater dry 

 weights for the tops, the decrease amounting to 50 per cent in the case 

 of culture 6. 



Magnesium sulphate w r as used alone in the series reported in 

 table 5. The decrease in growth is nearly proportional to the increase 

 in concentration of the added salt. In this series we have a very 

 marked decrease in the percentages of calcium and magnesium present 

 in the roots without any evident effect upon the growth of the plants, 

 especially that of the tops. Here again, however, we have increased 

 absorption of calcium as the percentage of magnesium increases, 

 even though the concentration of the former in the nutrient solution 

 is constant. It is of interest to note that the percentages of both ele- 

 ments in the tops throughout this series are low and vary but little, 

 regardless of the increasing concentration of the nutrient solution. 



Very marked antagonism between calcium chloride and magnesium 

 sulphate is shown in table 6. The dry weight of the plants grown in a 

 solution of magnesium sulphate .18 M. concentration was .29 gram, 

 but when .04 M. concentration of calcium chloride was added the aver- 

 age dry weight was 1.20 grams and in a concentration of .18 M. 

 magnesium sulphate and .24 M. calcium chloride the average dry 

 weight was .98 gram. Between these two concentrations of calcium 

 chloride the dry weights recorded are uniformly high. Correlated 

 with the rapid decrease in growth, in concentrations of .24 M. of cal- 

 cium chloride, is the marked increase in the percentage of both calcium 

 and magnesium found in the plants. The graphs representing the 

 amounts of these elements found crosses the growth graph coincident 



