2 BOTANICAL GAZETTE [JULY 
but these varied, as above noted, in the ratio in which they were 
present. Wheat plants were grown in these various cultures and 
observations were made in regard to general development, the effect 
on root growth, and appearance. The green weight of the plants 
was taken at the termination of the experiment. The solutions were 
changed every three days and an analysis made, the phosphate, nitrate, 
and potash being determined, thus giving the concentration of these 
constituents and the ratio existing at the end of every three-day 
period for comparison with the original concentration and ratio. This - 
changing of the solutions was kept up for twenty-four days, thus mak- 
ing eight changes. In this work the methods? devised in these labora- 
tories for the determination of small amounts of such constituents 
rendered excellent service and point a way for their further use upon — 
other problems in connection with the biochemical relationships of 
soils and plants, which have hitherto been impossible of attack. In 
the discussion and presentation of the results, the triangular diagram ~ 
as used in physical chemistry was employed, and has proven very 
useful as a guide in the work for the systematic handling of the experi- 
mental details. The results can best be presented and interpreted 
by itsmeans, and the method should prove very useful as a guide in ~ 
other lines of experimental work where similar relationships are 
involved. 
aerate 
The use of the triangular diagram as a guide in the work 7 
The number of solution cultures required in order to have all the 
possible ratios as outlined above is sixty-six. To bear in mind these 
ratios for three different ingredients, together with the ratios of the — 
solutions after the plants had grown, and perhaps also the ratios of © 
the material removed from the solution, a total of 594 numbers, is — 
practically an impossibility, and it is readily seen that in order to 
results can be kept in mind and the proper correlation and compari- 
sons made. The triangular diagram as suggested by SCHREINE- 
2 SCHREINER, O., and Fatryer, G. H., Colorimetric, turbidity, and titration 
methods used in soil investigations. ‘Bratietin 31, Bureau of Soils, U.S. Dept. Agric. 
1906. 
