568 The Philippine Journal of Science 1920 
From the dry-weight data of both series I and series II it ap- 
pears that for a given total concentration these plants were not 
very sensitive to small differences in the salt proportions. A 
relatively large number of salt combinations in both series I and 
series II gave approximately equal growth, with apparently iden- 
tical conditions other than those in the nutrient solution. Thus 
in series I eleven other solutions gave at least nine-tenths as 
high dry yields of tops as did the best solution; and in series II 
twelve other solutions gave at least nine-tenths of the yield of 
tops obtained in the best solution. The individual differences 
between the different plants in a culture is probably the greatest 
factor in determining just which set of a number of very favor- 
able sets of salt proportions will give the very highest yield. 
The relation between the cation-ratio values and the yields of 
wheat tops for series I and II are shown in Table 9. It will be 
seen that for low yields of tops the Mg/Ca-ratio values cover 
practically the whole range of these values for the entire series. 
There is thus no relation between the value of the Mg/Ca-ratio 
and the low yield of tops. The same thing is also true of the 
values of the Mg/K- and Ca/K-ratios, since all tested values of 
these ratios give low yields in some cultures. 
Table 9. — Cation-ratio values for solutions of series I and II; for the 
entire series, and for solutions giving high and low and highest and 
lowest top yields. 
Mg/Ca. 
Mg/K. 
Ca/K. 
■ 
Series 
I. 
Series 
II. 
Series 
I. 
Series 
II. 
Series 
I. 
Series 
II. 
Entire series; 
Minima T 
0.21 
0.21 
0.14 
0. 14 
0.08 
0.08 
Maxima - 
13.43 
13.43 
4.68 
4.68 
2.68 
2.68 
Range - - 
13.22 
13.22 
4. 54 
4. 54 
2. 60 
2.60 
Low yields: 
Minima _ 
0. 54 
0.21 
0. 14 
0. 14 
0.08 
0. 08 
Maxima. _ ____ 
13.43 
13. 43 
4.68 
4. 68 
2.27 
2. 68 
Range - 
12. 89 
13. 22 
4. 54 
4.54 
2. 19 
2.60 
High yields: 
Minima 
0.53 
0.53 
0. 14 
0. 14 
0.08 
0. 08 
Maxima ... _ 
3.52 
1.73 
0. 93 
0. 70 
0. 73 
0.45 
Range ... 
2. 99 
1.20 
0. 79 
0. 66 
0.65 
0. 37 
Highest yields _ . 
1.72 
1.72 
0. 40 
0. 29 
0. 23 
0. 17 
Lowest yields 
13. 43 
13. 43 
4. 68 
4.68 
0. 36 
0. 85 
Do 
11.35 
2.61 
0.23 
For high yields of tops, however, there does appear to be a 
certain relation between cation-ratio values and yield. High 
