SEEDLINGS IN ALKALINE SOLUTIONS 47 



Seedling Transference into Alkaline Solutions. This 

 practice has been preferred to germinating and growing 

 the plants in the alkaline solutions by some investigators. 

 Certain experiments have indicated that plants may 

 gradually become accustomed to salts as they grow older 

 so that the injurious strength of solution at one period 

 may not be so at another. By dipping the seedlings into 

 the alkali solutions at a definite period after germinating, 

 it has been hoped that a better standard for comparing 

 toxicity would be fixed. Fcr such work many standard 

 conditions have been suggested but few of these standards 

 have been accepted by other workers, so there is a wide 

 difference in the conditions under which the toxicity of 

 the plants have been determined. 



In the experiments of Kearney (13) and his co-workers 

 the roots of the seedlings were placed in the alkali solu- 

 tions for twenty-four hours and the death of the root tip 

 was taken to indicate the toxic limit for the plant. As 

 a result of this work, corn showed the toxic effect of mag- 

 nesium less than other salts, but with lupines, alfalfa, wheat, 

 sorghum, oats, cotton, and beets the magnesium compounds 

 were considerably more toxic than other salts. The sodium 

 chloride and sodium sulphate did not differ greatly in 

 toxicity to the different plants in several cases, and the 

 sodium carbonate was several times more toxic than these 

 two salts in most cases. Corn, which is considered rather 

 sensitive to alkali, endured more sodium carbonate than 

 the other crops, whereas sorghum, cotton, and beets, 

 which are usually resistant in soils, were affected most 

 by this salt in solution. The limits for wheat were 650 

 parts per million of sodium carbonate, 2610 parts per 

 million of sodium chloride, and 2830 parts per million of 

 sodium sulphate. Comparing the two series with lupines 



