REFERENCES 117 



transforming powers of the soil were better than the checks 

 when two salts, one of which was present in toxic quantities, 

 were present in the soil, or where both were in toxic 

 quantities for the single salts. The nitrogen-fixing or- 

 ganisms showed slight ' antagonism except between sodium 

 sulphate and sodium carbonate which showed no 

 antagonism. 



The exact cause of antagonism between the ions has 

 not been fully explained. Osterhout (17) found the 

 permeability of the protoplasm was rapidly increased until 

 death occurred when in solutions of sodium chloride. 

 With calcium chloride the permeability decreased to a 

 certain point after which it increased as with sodium 

 chloride until death occurred. He thinks that when a 

 substance like sodium chloride is brought in contact with 

 one like calcium chloride where the tendency is to cause 

 permeability in opposite directions, there is an antag- 

 onistic effect. He (17) thinks this interference of the ions 

 of the salts attempting to enter the cell may be the real 

 cause of the antagonism. Hansteen (2) thinks calcium 

 acts as an external protection to the roots of the plants, 

 which is essentially that of the above view. Le Clerc and 

 Breazeale (8) claim that lime overcomes the toxic effect 

 of the sodium salts without preventing the absorption of 

 sodium chloride by the plant. 



REFERENCES 



1. Caldwell, J. S. The Effect of Antagonistic or Balanced Solutions 



containing Sodium Chloride together with One of the Chlorides of 

 Calcium, Magnesium, Potassium, Strontium, Ammonium, or Copper 

 upon the Growth of Corn Plants Rooted in an Artificial Soil. Sci. 

 n. ser. 39 (1914), p. 293. 



2. Hansteen, B. The Relation of Plants to Certain Salts, I and II. 



Jahrb. wiss Bot. (Pringsheim), 47 (1910), No. 3. nn. 287-376. (Abs. 

 E. S. R. 23, p. 328.) 



