s, : pt. 1913.} x. MlFAKE-f-INFLUEXi K OF THE SALTS ETC. 175 



t 



From the results, they concluded that the different species 

 differ vastly in the absolute degree of their resistance to the 

 toxic action of these pure solutions, also the order of toxicity 

 of the several salts varies considerably according to the species. 

 Furthermore, the salts of magnesium are generally more toxic 

 than those of sodium to all the plants tested with the single 

 exception of maize. 



Burlixgh am x) has studied the influence of magnesium sul- 

 phate upon the growth of seedlings of abutilon, pea and corn, 

 and his results were summarized as follows : " magnesium sul- 

 phate in solutions of greater concentrations than has a 



8192 



toxic action on most seedlings, the degree of toxicity varying 



with the type of seedlings and with the conditions. An - 



solution is toxic to pea seedlings, slightly stimulating to abut- 

 ilon, while it has a marked stimulating effect on corn seedlings. 

 Maximum stimulation in magnesium sulphate results in solution 



fr ° m 39768 t0 131072 ' the point a £ am varying according 

 to the kind of seedling grown. When magnesium sulphate is 

 used in proper dilutions there may be produced a total growth 

 nearly double that in the control ; or in the case of abutilon 

 seedlings, a growth of the primary root increased, but the 

 lateral roots develop sooner, are more numerous, and attain a 

 greater growth. Furthermore, the stimulation is not limited to 

 the root sj'stem, but the magnesium forces a more rapid and a 

 greater growth of the hypocotyl and plumule. In this same 

 concentration, calcium nitrate causes very little stimulation. 



In addition to the marked stimulation which magnesium 

 sulphate causes when it is used in dilutions from goo ^ to 



- )OQO , it increases the vitalitv of the seedlings. The seed- 

 o2-i2oo 



lings grown in the magnesium sulphate outlived those in the 

 control by two or three weeks, and in some cases by a greater 

 period. 



1) Journ. Amer. Chem. Soc, Vol. 29, PP. 1905-1112 (1907). 



