Experiment II
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ehavior of Nitrates when Total Concentrations are Reversed In the foregoing experiment the three solutions differed in total con-centration as well as in the concentration of nitrates. It happened thatthe solution with the highest nitrate . content had also the highest totalconcentration. The question is naturally raised, then, as to whether ornot the increased concentration of the solution rather than the increasednitrate content is responsible for the increased ratio of tops to roots. Thisquestion has led to the arranging of a second experiment in order to throwlight on this phase of the problem. It is recalled here that Stiles and MissBrenchley found that the top-root ratios decreased as the concentrationwas decreased. For this experiment, Solution II (medium nitrate) remained as inExperiment I. The low-nitrate solution is modified and designated Solu-tion la. In this, the nitrate content is kept the same, but the other saltcomponents are increased to .5 gram per liter, which makes the modifiedsolution about 5 times the original, Solution I. The high-nitrate solution isdesignated Solution 1 1 la; it likewise retains the same amount of nitrateas before, but the remaining six salts are reduced to .06 gram each, therebyreducing the total concentration of the solution about one seventh. Thecomposition of the solutions used in Experiment II was as follows:
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