354 Journal of Agricultural Research voi. xviii, No. 7 



SERIES 12 



In the experiments previously conducted, the calcium salts were added 

 at the rate of 30 parts per million. Smaller amounts were now added to 

 determine the minimum amount of lime that could exert an appreciable 

 effect upon plants growing in a toxic salt. Plate 47, A, shows plants 

 grown in the following solutions: 



SOLUTION NO. CONCENTRATION OF SOLUTION. 



1 4,000 parts per million of sodium chlorid. 



2 Distilled water. 



3 4,000 parts per million of sodium chlorid + 40 parts per million of cal- 



cium oxid. 



4 4,000 parts per million of sodium chlorid + 30 parts per million of cal- 



cium oxid. 



5 4,000 parts per million of sodium chlorid + 20 parts per million of calcium 



oxid. 



Forty, 30, and 20 parts per million of lime entirely overcame the 

 depressing action of the sodium chlorid and produced plants equal to 

 those grown in distilled water. 



SERIES 13 



In Plate 47, B, are shown plants grown in the following solutions; 



SOLUTION NO. CONCENTRATION OF SOLUTION. 



1 4,000 parts per million of sodium chlorid. 



2 4,000 parts per million of sodium chlorid + 15 parts per million of cal- 



cium oxid. 



3 4,000 parts per million of sodium chlorid + 10 parts per million of cal- 



cium oxid. 



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



oxid. 



5 4,000 parts per million of sodium chlorid + i part per million of calcium 



oxid. 



From Plate 47 it will be seen that the size of the plants decreases 

 gradually as the concentration decreases from 40 parts to i part per 

 million of lime. Much better plants were grown in the solutions con- 

 taining 2 parts and i part per million, respectively, than in the solution 

 containing no lime. It is evident that the presence of calcium salts, 

 even in most minute quantities, materially affects the tolerance of young 

 wheat seedlings for sodium chlorid. 



SERIES 14 



No satisfactory explanation has yet been given for the effect of calcium 

 salts on the toxic properties of other salts. W. J. V. Osterhout^ con- 

 cluded, on the basis of a series of experiments, that entrance of ions of 

 sodium chlorid into the protoplasm was greatly hindered or prevented by 



> OSTERHOUT, W. J. V. THE PERMEABILITY OF PROTOPLASM TO IONS AND THE THEORY OF ANTAGONISM. 



/n. Science, n. s. v. 35, no. 890, p. 112-115. 191a. 



