264 
K. MIYAKE. 
eight different land plants and found that the presence of calcium sulphate 
tends very greatly to diminish, not only the differences between different 
species as to their tolerance of magnesium and sodium salts, but also the 
differences between the latter in their toxicity to the same species, and 
the neutralizing effect of calcium sulphate is generally much more marked 
with the magnesium than with the sodium salts. 
In 1907, Benecke" also studied the poisonous action of various 
salts upon the growth of spirogyra. The result of his investigation was 
summarized as follows : chloride, nitrate, sulphate and phosphate of sodium 
potassium, magnesium and iron are more or less poisonous, and among 
these cations iron and magnesium are more poisonous than potassium, 
sodium is less poisonous than potassium; among the anions, chlorine is 
least poisonous. The toxicity of these anions and cations can be neutral- 
ized or decreased by the addition of calcium iron. Loew and Aso z) 
also studied the same subject in relation to spirogyra and observed that 
calcium salts can prevent the toxic effects of magnesium salts while 
potassium salts can retard but not entirely prevent the injurious action 
of the same. 
T a k e u c h i :,) pointed out, at the end of his investigation of the 
behavior of algae in relation to salts at certain concentration, that the 
injurious action of magnesium salts can only completely be overcome by 
calcium salts, and not by sodium or potassium salts, which has been 
observed not only with algae, but also with young plants of barley and 
maize which were deprived of their endosperm, 
Hansteen 4 ' has recently investigated the antagonism between cations 
upon the growth of wheat seedlings and shown that the pure solution of 
potassium, sodium and magnesium salts are more or less injurious accord- 
ing to their concentrations. But in combination with calcium salts, their 
injurious effect on the growth of leaves, roots and root-hairs is greatly 
1) . Benecke, — Ber. D. bot. Ges., 25, P- 322 (1907). 
2) . I. o e w and A so, — Bull. Coll.Agric, Tokyo Imp. Univ., 7» pp. 395 _ 4°9 (1906-1908). 
3) . T a k e u c h i,— Bull. Coll. Agric, Tokyo Imp. Univ., 7, P- 628 (1906-1908). 
4) . Hansteen, — Nyt. Mag. Naturvidensk., 47, PP- 181-192 (1909); ref. Exp. Sta. Ree, 
U. S. Dept. of Agriculture, 23, P. 28 (1910). 
