16,6 Espino: Salt Requirements of Young Rice Plants 5 I 7 
best cultures of solution type B, it is concluded that this type 
is not at all well suited to the growth of these young rice plants, 
at least under the non-solution conditions here dealt with. A 
direct and simultaneous comparison between some of the best 
sets of salt proportions for type B with some of the best ones 
for type A will be considered in the following section of this 
paper. 
It should be remembered that 4-salt solution type B represents 
only one of many possible ways by which the ions potassium, 
calcium, magnesium, ammonium, phosphate, and sulphate might 
be brought together in solutions, without any nitrate, and the 
failure of any of these sets of salt proportions to give satisfactory 
growth in the plants here used is not to be regarded as definite 
proof that young rice plants actually require the nitrate ion. 
All that may be said is that these plantlets grew excellently well 
with certain sets of salt proportions of the 4-salt solution type 
with both ammonium and nitrate, while no set of proportions 
tried with ammonium but without nitrate gave passable devel- 
opment, on account of the generally present leaf injury. 
FINAL COMPARISON BETWEEN THE THREE DIFFERENT SOLUTION TYPES 
After the experiments whose results have thus far been con- 
sidered had been completed and after the data given by them 
had been studied to some extent, but before the method of basing 
conclusions on agreement in group designations had been hit 
upon, the apparently best three sets of salt proportions were 
selected from each of the three solution types, for each of the 
lowest two total concentrations, and these were employed in a 
set for simultaneous test. In this lot there were thus six solu- 
tions of 4-salt type A, six of 4-salt type B, and three of 3-salt 
type I (increments of one-seventh). To these were added two 
different total concentrations of Shive’s best solution for young 
wheat plants (3-salt type I, osmotic proportions, increments of 
one-tenth). Four like cultures, of 6 plants each, were employed 
in each case. The methods and treatment were the same as for 
the preceding larger series, and the culture period was from 
March 13 to April 3, 1919. The solution characteristics and the 
dry-yield data for tops, roots, and entire plants (each represent- 
ing 6 plants but each derived as an average from four like cul- 
tures of 6 plants each) are presented in Table 15. The nu- 
merical data are all expressed in terms of the corresponding yield 
value for solution AT1R2S1 (0.0016 gram-molecule per liter, 
or 0.08 atmosphere), taken as unity, the actual value for this 
solution being given in parentheses beneath the value 1.00. 
