286 
K. MIYAKE. 
IV. A most favorable Ratio of Calcium to 
Magnesium or Sodium for the Neutralization 
of the Toxicity. 
It was shown in previous chapter that the toxicity of various salts 
common in alkali soils is a specific property of the ions. It has also 
been shown that a mixture of two salts, both of which are toxic in pure 
solution, is much less injurious than either one alone, or that there is an 
antagonistic action of the salts. The strength of the antagonism varies 
between .the different cations. 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 cations is almost 
completely neutralized. 
Without further consideration it will be easily seen that the signifi- 
cance of an antagonism between two salts, specially calcium and other 
cations, is very great in the proper management of alkali soils. In view 
of this consideration, it will be of vast interest to find a suitable ratio 
between calcium and other cations, at which the plant can grow most 
favorably, under varying concentrations. To determine this, calcium 
chloride was added to the solution of the chloride of magnesium or of 
sodium in such amount that all the culture solutions in a series would 
contain the same amount of chlorine, with but varying ratios of calcium 
to magnesium or sodium. Fifteen different ratios were tried, namely 
15 : 15, 14 : 16, 13 : 17, 12 : 18, II : 19, 10 : 20, 9 : 21, 8 : 22, 7 : 
23, 6 : 24, 5 : 25, 4 : 26, 3 : 27, 2 : 28, 1 : 29 ; each series being under 
three different concentrations of 1/20, 1/10 and 1/5 normal of the salts 
tested. 
The experiments were conducted in beakers of about 5.5 cm. in 
diameter and 7 cm. deep, each containing 30 cc. of the solutions as noted 
in the following tables. The seeds of almost uniform size and specific 
gravity were germinated in glass dishes containing distilled water. When 
the plumules were about 20 mm. long four seedlings were transferred to 
