i7, 6 Trelease : Salt Requirements of Wheat Plants 573 
thirty-six solutions having various proportions of monopotassium 
phosphate, calcium nitrate, and magnesium sulphate, all of 
which have the same total concentration (1.75 atmospheres). 
None of these solutions contains any potassium chloride at all. 
The set of cultures represented by triangle 2 may be considered 
as derived from Shive’s series by first decreasing the total con- 
centration of the latter to 1.28 atmospheres and then adding to 
each solution enough potassium chloride to give a total concen- 
tration of 1.60 atmospheres. Similarly, the sets represented by 
triangles 7, 8, and 9 may be derived from the Shive set by de- 
creasing the total concentration to 0.48 atmosphere, 0.32 atmos- 
phere, and 0.16 atmosphere, respectively, and then adding 
potassium chloride equivalent to 1.12 atmospheres, 1.28 atmos- 
pheres, and 1.44 atmospheres, respectively. It is thus seen 
that series III was planned to study the various physiological 
values (as indicated by the plants) of the different salt propor- 
tions in the Shive series, in the presence of four different partial 
concentrations of potassium chloride, the total concentration of 
the four-salt mixture being always the same (1.60 atmospheres) . 
The actual salt proportions tested in this series were not 
exactly the same as those employed by Shive, but the total range 
of salt proportions was the same. Instead of the thirty-six 
solutions tested by Shive, ten selected solutions were here em- 
ployed. Only three of these ten correspond to sets of propor- 
tions actually used by Shive (those represented by the three 
apices of the diagram). The others fall on the diagram at 
different points from those actually tested by Shive, but they 
may be designated in the same general manner as was followed 
by Shive, by employing fractional numerals somewhat as in the 
case of series II. Culture T2R44C1, for example, considered as 
a three-salt solution having an osmotic value of 1.28 atmospheres 
has 0.4^ due to monopotassium phosphate, 0.1 due to calcium 
nitrate, and 0.4| due to magnesium sulphate, and the amount 
of potassium chloride present is shown by the number of the 
triangle (0.2 of 1.60=0.32 atmosphere) . Besides the forty solu- 
tions belonging to this series, solution T2R4C2 (giving the high- 
est top yield in series I) was also employed, for the sake of 
comparison. 
Table 11 gives the chemical composition of each of the forty 
solutions in series III, in terms of the partial volume-molecular 
concentrations of the four salts ; the values of the three cation 
ratios are also included in this table. The method used in cal- 
