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1910] SCHREINER & SKINNER—ABSORPTION AND GROWTH 29 
the rate of decrease per unit of green weight are consistent in showing 
that relatively more was absorbed when more was present, although 
the plant does not seem to have been able to utilize this increase 
economically in its growth. This tendency is especially marked in 
the case of phosphate and potash, although it is also shown to an 
appreciable extent in the case of nitrogen. 
As will appear in future publications, this general method of 
experimentation was used for the purpose of studying the effect of 
individual soil contituents and other organic compounds by using 
them in uniform concentration in all the cultures of a triangle. In 
these studies it was necessary to grow a control set without the con- 
stituent to be studied, so that the foregoing experiment was in this 
manner repeated a number of times, and the general results thus 
obtained were in harmony with those here recorded. 
Summary.“ 
In this study the growth relationships and concentration differences 
were observed between solution cultures in which the phosphate, 
nitrate, and potash varied from single constituents to mixtures of 
two and three in all possible ratios in ro per cent stages. 
The better growth occurred when all these nutrient elements were 
present, and was best in those mixtures which contained between 
ro and 30 per cent phosphate, between 30 and 60 per cent nitrate, — 
and between 30 and 60 per cent potash. The growth in the solutions 
containing all three constituents was much greater than in solutions 
containing two constituents, the solutions containing the single con- 
stitutent giving the least growth. 
The concentration differences noticed in the solutions were also 
very striking, the greater reduction in concentration occurring where 
the greatest growth occurred. 
The change in the ratios of the solutions and the ratios of the 
materials that were removed from the solutions showed that where 
the greatest growth occurred, as above outlined, the solutions suffered 
the least change in ratio, although the greatest change in concentra- 
tion occurred. 
The more the ratios in these solutions differed from the ratios in 
which the greatest growth occurred, the more were the solutions altered 
