INFLUENCE OF THE ALKALI SALTS UPON TAE GROWTH OF RICE PLANTS- 27 1 
between two different cations, since the anions were the same in all the 
combinations. 
In a favorable mixture of sodium and potassium, sodium and mag- 
nesium, potassium and magnesium ions, the length of leaf became almost 
equal to that of control plant, but the growth and the number of roots 
were invariably poor. It is evident, therefore, that the toxic effect of 
sodium, potassium and magnesium ions was mutually counteracted by 
combination of each other, but not completely neutralized. The curve of 
antagonism between sodium and potassium ions shows two maxima and 
the location of these maxima is almost constant, occurring at the point 
of the proportion of 5 : 25. It is also seen that the potassium ion has 
superior efficacy over the sodium ion in neutralizing the toxic effect of 
each other. The neutralizing power of magnesium ion toward the toxic 
effect of sodium or potassium ion was greater than that of sodium or 
potassium to magnesium as in the case of 1/10 N. NaCl 25 cc. + 1/10 N. 
MgCl 2 5 cc, 1/10 N. Na 2 S0 4 25 cc. + 1/10 N. MgS0 4 5 cc. or 1/10N. 
KCl 25 cc. + 1/10 N. MgCl 2 5 cc, when the highest development of the 
seedlings was really observed. 
On the other hand, in a mixture of sodium and calcium, potassium 
and calcium, magnesium and calcium ions in proper proportions, the toxic 
effect of these ions is almost mutually counteracted and a medium is pro- 
duced in which the plant may grow almost perfectly. The toxic effect 
of sodium, potassium and magnesium ions almost completely disappeared 
when a little calcium ion is added ; on the contrary, the poisonous effect 
of calcium ion was excluded only by the addition of a large amount of 
other ions. 
B. The Antagonism between two Salts with different 
Anion but same Cation. 
In the above nine combinations, we examined the antagonisms between 
the metallic ions in regard to their toxic effects upon the growth of rice 
seedlings. We then undertook to investigate the question of the mutual 
