K. MIYAKE, 
6) Among the divalent cations, calcium shows a more marked an- 
tagonism than magnesium. The presence of calcium in a culture medium 
is an essential factor for the growth of plants especially for root growth 
and only in such case, toxic effect of other ions is completely disappeared. 
7) The anions are almost equally antagonized by each other. The 
curve of antagonism between the anions shows, therefore, two maxima as 
in the case of sodium and potassium. 
8) The neutralizing power of S 0 4 " toward the toxic effect of Cl' 
seems to be greater than that of Cl' to S 0 4 ". Again, NO s ' seems to have 
superior efficacy over S 0 4 " in neutralizing the toxic effect of the other. 
9) The combined antagonistic actions of cations and anions have a 
more favorable effect than that of one of them, though the antagonism 
between anions in such case seems to be overcome to a large extent by 
that between cations. 
III. Can Barium or Strontium replace Calcium 
in its antagonistic Action? 
In the previous chapter, it was pointed out that the injurious action 
of the metallic ions upon the growth of rice seedlings is perfectly neutral- 
ized by the presence of calcium ion. Whether or not barium and 
strontium which are so similar in chemical properties with calcium, can 
exert the same beneficial action as calcium in counteracting the toxic effect 
of other metallic ions forms an important subject of study. For the solu- 
tion of this problem the following experiments were made. 
A. Experiment with MgCl^. 
Twenty beakers of about 5.5 cm. diameter and 7 cm. deep, served 
for the experiment. While 1 beaker which contained 30 cc. of distilled 
water, served as check, the other 19 beakers received 1/10 N. MgCl a 30 
cc,, 1/10 N. MgCI a 25 cc. + 1/10 N. CaCl a 5 cc., 1/10 N. MgCl a 20 cc. 
