-11- 



inorganic chemicel elements that (together with iron, 

 which was not included), constitute the inorganic elements 

 essential fcr plant grove th in general. 



The tv/enty-one different solutions of each type 

 differed from one another in their molecular salt proportions, 

 as shown above. The solutions were made up thirty (or, in 

 some cases, ten) times as concentrated as they were to be 

 needed, and the stock concentrated solutions thus obtained 

 were properly diluted whenever culture solutions were 



requlr ed. 



Nine single-ealt solutions, each representing 

 one of the nine salts , were first prepared, these 

 having the following volume-molecular concentrations: 

 KH2PO4, 1.0 mol.; KNO3, 1 mol.; KgSO^, 0.4 mol.; Ga(HgP04)2, 

 0.1 mol.; Ca(N03)2. 1»9 mol., CaS04, .014 (satvtrated solution 

 at room temperature); Mg(H2F04)^ 0. 1 mol.; Mg(N05)2, 1.0. mol.; 

 MgS04, 1.0 mol. The 126 concentrated stock nutrient solutions 

 were each prepared by mixing proper volumes of the proper 

 three single- salt solutions with distilled water in requisite 

 volume, care being exercised to prevent precipitation. 



For solution types I, II, III and IV (without 

 GaS04), the concentrated stock nutrient solutions were thirty 

 times as concentrated as those actually used for the culture 

 tests. For solution types V and YI (with CaSO.i ) , the concen- 



