474 
Philippine Journul of Science 
1920 
tion made up of monopotassium phosphate, each of those of 
the front margin of each triangle has one-eighth made up of 
ammonium sulphate, every one of the left margin of each trian- 
gle has one-eighth made up of calcium nitrate, and every one 
of the right margin has one-eighth made up of magnesium sul- 
phate, etc. The solution at the top apex of the solid diagram 
(T5R1S1) has the salt monopotassium phosphate represented 
by five-eighths of its total molecular concentration, while each 
of the remaining three salts is represented by only one-eighth 
of the total. 
The different sets of molecular salt proportions for solution 
types A and B, and the molecular partial concentrations of the 
one salt monopotassium phosphate, are shown in Table 2. From 
these data the molecular partial concentrations of the other 
three salts can be readily computed. 
Four-salt type B . — (Monopotassium phosphate, monocalcium 
phosphate, magnesium sulphate, ammonium sulphate.) This 
type of solution differs from type A only in this particular, 
that it contains no calcium nitrate but has its calcium supplied 
as monocalcium phosphate. While type A contains both am- 
monium and nitrate as the nitrogen-bearing ions, type B contains 
only ammonium. Type B was studied in the same way as type A 
and the solution designations, salt proportions, total molecular 
concentrations, etc., are alike for the two types. 
THE ClILTUEn SOLUTIONS 
Each time a supply of culture solution was required, for start- 
ing a culture or for the renewal of its solution, this supply was 
prepared by merely drawing off some of the corresponding stock 
solution (in a few cases) or else by diluting some of that stock 
solution, the degree of dilution being of course determined by the 
total concentration required for the particular culture in ques- 
tion. Finally, after the solution for any series had been placed 
in the culture bottles, the ferric phosphate suspension was added. 
The culture solutions thus prepared were not stored in quantity 
and each lot was always placed at the disposal of the plants 
within twenty-four hours after it had been made up. 
In renewing the solutions a set of culture bottles were first 
prepared and filled with their respective solutions. Then each 
cork, bearing its plants, was transferred from the bottle used 
during the previous period to the corresponding bottle of the 
newly prepared set. The plants were thus out of solution only 
momentarily. 
