follov/ing the general out lines v;orl<ed out by Schreiner and 



(4) 

 Skinner* and other v/riters, for the experimental study of 



different proportions of the same salts as such differences 



influence plant grov»'th. The Livingston-Tottingham scheme 



embraces what they call six types of solutions, each being 



characterized by the three main salts employed. All 



solutions were to lirve a trace of iron as ferric phosphate, 



the amount of tiiis salt used for unit voliame of solution 



being alviays the same. ITae three main salts for each 



(4) 



'Schreiner, 0., and Skinner, J.J. , Ratio of phos- 

 phate, nitrate anr" potassiiom on absorption and gro'.^th* 

 3ot. Gaz. 50:1-30. 1910. 



Idem. Some effects of a harmful organic constituent. 

 U.S. Dept. Agric. Bur. Soils. Bui. 70. 1910. 



Tottinghara, "' .E. A quantitative chemical and physiolog- 

 ical study of nutrient solutions for p^ant cxiltiire . Physiol. 

 Res. 1:133-245. 1914. 



Shive, J.. 7. A study of the physiological balance in 

 nutrient media. Physiol. Kes. 1:327-397. 1915. 



licCall, A.G. The physiological bal- nc e of nutrient 

 solutions for plants in sarti cultures. Soil Sci. 

 2:207-253. 1916. 



Idem. The physiological requirements of v;heat and soy 

 beans growing in sand media. Proc. Soc. Prom. Agric. Sci. 

 1916:46-59. 1915. 



Hibbard, R.P. Physiological balance in the soil solu- 

 tion. T'ich. Agric. b;xp. Sta . Tech. Bui. 40. 1917. 



Shive, J.'V. A study of physiological balance for buck- 

 wheat grown in tliree salt solutions. N.J. i^gric . rixp. Sta. 

 Bui. 319. 



KcCall, A.G. and Richards, P.E. Mineral food requirements 

 of \lheBit plant at different sta.es of its development. 

 Jour. Amer. Soc. Agron. 10:127-134. 1918. 



Shive, J. 17. and Martin, ".H. A Comparison of salt require- 

 ments for young and for mature bixclnvheat plants in water cultures 

 and sand cultures. Amer, Jour. Hot. 5: 186-191 .1918. 



Idem. A Comparative sttody of salt requirements for young 

 and matiire buck^r/heat plants in solution cultures. Jour, -t^gric . 

 Res. 14:115-175. 1918. 



■ Schreiner, 0., and Skinner, J.J. 'i'he triangle system for 

 fertilizer exp'^iments. Jour. Amer. Soc. Agron. 10:225-246.1918. 



