tgi0o]) SCHREINER & SKINNER—ORGANIC SOIL CONSTITUENT 165 
Solution cultures containing the three fertilizer ingredients, 
namely P,O,, NH,, and K,O, as calcium acid phosphate, sodium 
nitrate, and potassium sulfate, respectively, in all possible ratios 
of one, two, and three constituents, varying them in stages of 10 
per cent, were prepared, the concentration being 80 parts per 
million in these constituents. In a similar set of cultures there 
Fic. 2.—Wheat seedlings grown in solutions of dihydroxystearic acid from soils: 
1, solution of dihydroxystearic acid, 200 parts per million; 2, too parts; 3, 50 parts; 
4, 20 parts; 5, control in distilled water 
was added so parts per million of dihydroxystearic acid to each 
culture. The selection of the salts as carriers of the phosphate, 
nitrate, and potash, and the terms P,O,, NH,, and K,O are in har- 
mony with the practice in fertilizer work. The salts selected, it will 
be seen, are also carriers of calcium, of sodium, and of sulfate, and 
the three salts, therefore, were practically the best that could be 
selected for giving at the same time other needed constituents. 
The details of this method of experimentation have been given in 
