INFLUENCE OF THE ALKALI SALTS UPON THE GROWTH OF RICE PLANTS. 281 
As will be seen in the above results, in a suitable mixture of these 
salts, except calcium salt, their toxic effects disappear largely but not 
completely while in a mixture with calcium salt in a favorable propor- 
tion, the toxic effect of each salt completely disappears and a medium is 
produced in which the plant may grow almost perfectly as in the case 
of the antagonism between cations already observed. The presence of 
calcium ion in a culture medium seems to be a most important factor for 
the growth of plants and especially for root growth. 
It is also observed that the combined antagonistic actions of cations 
and anions have a more favorable effect than that of either one of them, 
though the antagonism between anions in such case seems to be overcome 
to a large extent by that between cations. 
D Summary. 
From the above results, we may summarize as follows : 
1) The salts under examination, used separately, are very poisonous 
in 1/10 normal concentration upon the growth of rice plants, but when 
the two salts are mixed with each other in a suitable proportion, the toxic 
effect of each salt more or less completely disappears. The result is of great 
importance in alkali soil investigations and forms an important factor in 
the question of soil fertility. 
2) The antagonistic action of salts is due to that of the ions formed 
by the dissociation of the salt. 
3) The antagonism between anions is weak in comparison with that 
between cations. 
4) Among cations, divalent cations are markedly antagonistic to 
monovalent, but on the contrary, monovalent cations do not strongly 
antagonize divalent cations. 
5) The monovalent cations, sodium and potassium, are antagonized 
by each other. Consequently, the curve of antagonism between these ions 
shows two maxima, but the antagonistic power of potassium to neutralize 
the toxic effect of sodium is greater than that of sodium to potassium. 
