33] Stoffaiifnahme. 389 



this series of experiments with the wMte lupine may be summarized as foUows: 

 1. When the nitrates of calcium, magnesium and potassium are offered in 

 pairs in Solutions varying in concentration from 120 N x 10-^ to 480 Nx 10~^ 

 it is usually the case that the roots absorb more electrolytes than from the 

 pure Solutions. It seems also true that for the ränge of concentration here 

 concerned absorption tends to increase in mixtures as well as in pure Solutions 

 as the salt content increases. The case of magnesium offers an exception 

 owing to the narrow ränge of physiologically useful concentrations of the 

 Mg ion. 2. In mixtures of Ca(N03)2 and KNO3 the inimical effect of K ions 

 on root absorption is seen in the high ratio of Ca to K required to give maximum 

 absorption, viz., 3 Ca": 2K* (3 Ca[N03]2 + Va KNO3) in all concentrations 

 tested. The value of a small amount of K ions is however proved by the excess 

 of al)sorption in the mixture over that in Ca(N03)2 alone. The absolute amount 

 of Ca present in mixtures seems to be of great influence since as the proportion 

 of Ca increases in the greater dilutions, absorption is increased. The favorable 

 influence of Ca ions is therefore striking in the mixtures as well as in the 

 piiro Solutions. 3. In mixtures of Ca(N03)2 and Mg(N03)2 the greater absorption 

 of the Mg ion in comparison with the K ion appears in the greater proportion 

 of Mg to Ca Seen in the most favorable ratio. The greatest absorption is found 

 in the ratios 2 Ca": 2 Mg" or 1 Ca**: 3 Mg" in the concentrations here tested. 

 The great significance of even a small proportion of Ca is seen in the relatively 

 high absorption made in a mixture containing 1 Ca to 9 Mg at the highest 

 concentrations here tested. 4. In pure Solutions the Mg ion is much more 

 favorable to absorption than the K ion in the weaker concentrations while 

 the K ion is more favorable in the highest concentration. They are absorbed 

 to about the same extent at a concentration of 360 N x 10"~^. Absorption 

 from mixtures exceeds that from either puie Solution except in the weakest 

 concentrations. Although a most favorable ratio can hardly be designated, 

 the general tendency of the resxüts seems to indicate that a high proportion 

 of Mg is more favorable in weaker concentrations." 



366. True, Rodney H. and Bartlett, Harley Harris. The exchange 

 of ions between the roots of Lupinus albus and culture Solutions 

 containing three nutrient salts. (Amer. Journ. Bot. III, 1916, p. 47 

 bis 57, mit 3 Fig.) — Summary: ,,1. In general. seedlings of Lupinus albus L. 

 absorb more salts from mixtures of the nitrates of potassium, calcium and 

 magnesium than from equally concentrated Solutions containing only one 

 or two of these nitrates. 2. The Solutions of the 3 nitrates which were most 

 favorable to absorption were much inferior to corresponding Solutions in which 

 three anions, H2PO4-, NO3-, S0«=, were present. Under fairly comparable 

 couditions the roots were able to absorb about half of the salts from the best 

 Solutions of the 3 nitrates and 85 percent from corresponding Solutions with 

 mixed anions. 3. In Solutions of KNO3, Ca {N03)2 ^^d Mg(N03)2, as well as 

 in Solutions of KH2PO4. Ca{N03)2 and MgSO^ the best absorption occurs 

 when no simple ion greatly predominates over the rest. Nevertheless, there 

 is a Wide ränge of Variation in the proportion of different ions, witliin which 

 ränge the roots absorb with almost equal ef f eciency. ' ' 



367. Tschirch, A. La membrane siege du travail chimique. 

 (Bnll. Soc. vaudoise Sc. nat. L, 1915, p. 297-309.) 



368. Vageier, H. Ein Beitrag zur Frage der Wirkung von 

 Mangan. Prisen und Kupfer auf den Pflanzenwuchs. (Landw. 



