Jan. 2, 1920 Lime and Sodium-Chlorid Tolerance of Wheat Seedlings 351 



which had passed through the sand and likewise in the solutions which 

 had passed through the soil were similar to those grown in the sand and 

 soil. It is evident, therefore, that in passing through the soil the solution 

 was so altered as to overcome almost completely the toxic efifect of the 

 sodium chlorid. 



SERIES 6 

 On March 1 3 another set was started with the following solutions : 



SOIUTION NO. CONCENTRATION OP SOLUTION. 



1 4,000 parts per million of sodium chlorid. 



2 6,000 parts per million of sodium chlorid filtered through the soil. 



3 8,000 parts per million of sodium chlorid filtered through the soil. 



4 4,000 parts per million of sodium chlorid filtered through the soil. 



5 4,000 parts per million of sodium chlorid added to distilled water that had 



previously been filtered through the soil . 



6 4,000 parts per million of sodium chlorid + 100 parts per million each of 



sodium nitrate, potassium chlorid, and sodium phosphate. 



On March 20 the plants were photographed (PI. 43, A). It will be seen 

 that vigorous plants were obtained in solution 3 in a concentration of 

 8,000 parts per million sodium chlorid, or double the amount necessary 

 to stop the growth in distilled water, by simply filtering the salt solution 

 through the soil. Good plants were also obtained in solution 5 to which 

 the salt had been added after the distilled water had been passed through 

 the soil. In solution 6 the addition of the fertilizer salts produced com- 

 paratively little better growth than was noted in the control. 



Two hundred cc. of water were then passed through a fresh pot of soil 

 and analyzed. The salt content of the solution showed 31 parts per mil- 

 lion of calcium oxid. This suggested the possibility that lime might be 

 the cause of the greater tolerance noticed in all the soil pots. 



SERIES 7 



To test the effect of lime the following set was started : 



SOLUTION NO. CONCENTRATION OP SOLUTION. 



1 4,000 parts per million of sodium chlorid. 



2 4,000 parts per million of sodium chlorid + 30 parts per million of calcium 



sulphate. 



3 4,000 parts per million of sodium chlorid + 30 parts per million of calcium 



oxid. 



4 4,000 parts per million of sodium chlorid + 30 parts per million of mag. 



nesium bicarbonate. 



On March 29 the plants were photographed (PI. 43, B). The magne- 

 sium salt had little effect, but the calcium sulphate and calcium oxid 

 were about equally effective in overcoming the toxic action of sodium 

 chlorid. 



