72 Journal of Agricultural Research Voi. xvni. No. 2 



(4) The losses observed occurred when the constituents of the water 

 extracts of the soil were at or approaching their minima and when these 

 same constituents were moving from the leaves to the heads. 



(5) The suggestion is offered that for many plants high concentra- 

 tions of the soil solution at certain stages of growth are probably not 

 necessary and may be undesirable. 



(6) A plea is made for further studies of other types of plant by the 

 methods used herein, to obtain data for the more rational formulation 

 of experiments with sand and water cultures. 



LITERATURE CITED 

 (i) BuRD, John S. 



19 18. WATER EXTRACTIONS OP SOILS AS CRITERIA OP THEIR CROP-PRODUCING 



POWER. In Jour. Agr. Research, v. 12, no. 6, p. 297-309, i fig. 



(2) HOAGLAND, D. R. 



I918. THE FREEZING-POINT METHOD AS AN INDEX OF VARIATIONS IN THE SOIL 



SOLUTION DUE TO SEASON AND CROP GROWTH. In Jour. Agr. Research, 

 V. 12, no. 6, p. 369-395, 9 fig. Literature cited, p. 394-395. 



(3) 



I919. THE RELATION OF THE CONCENTRATION AND REACTION OP THE NUTRIENT 

 MEDIUM TO THE GROWTH AND ABSORPTION OP THE PLANT. In Jour. 



Agr. Research, v. 18, no. 2, p. 73-117. 



(4) HORNBERGER, R. 



18S2. CHEMISCHE UNTERSUCHUNGEN iJBER DAS WACHSTHUM DER MAISPFLANZE. 



In Landw. Jahrb., Bd. 11, p. 359-523, pi. 2-15. 



(5) Jones, W. J., Jr., and Huston, H. A. 



I914. COMPOSITION OP MAIZE AT VARIOUS STAGES OP ITS GROWTH. Ind. Agr. 



Exp. Sta. Bui. 175, p. 599-630, 10 fig. 



(6) LeClERC, J. A., and BrEazEalE, J. F. 



1909. PLANT FOOD REMOVED FROM GROWING PLANTS BY RAIN OR DEW. In U. S. 



Dept. Agr. Yearbook, 1908, p. 389-402. 



(7) LlEBSCHER, G. 



1887. DER VERLAUF DER NAHRSTOFFAUFNAHME UND SEINE BEDEUTUNG FUR DIE 



DiJNGERLEHRE. In Jour. Landw. Jahrb. 35, p. 335-518. 



(8) Stewart, Guy R. 



I918. EFFECT OF SEASON AND CROP GROWTH IN MODIFYING THE SOIL EXTRACT. 



In Jour. Agr. Research, v. 12, no. 6, p. 311-368, 24 fig., pi. 14. Liter- 

 ature cited, p. 364-368. 



(9) WiLFARTH, H., RoMER, H., and Wimmer, G. 



1905. iJBER DIE NAHRSTOFFAUFNAHME DER PFLANZEN IN VERSCHIEDENEN 



ZEITEN IHRES WACHSTUMS. In Landw. Vers. Stat., Bd. 63, Heft 1/2, 

 p. 1-70, pi. 1-3. 



