Rate of Absorption of Various Salts by Plant Tissue. 



501 



The anions are absorbed initially in the order SO4, NO3, CI, but this gives 

 place later to the order ISTOs, CI, SO4, owing to the slowing down of the rate 

 of absorption of sulphate. 



These conclusions agree well with the results of earlier workers. Euhland 

 (9) showed that potassium and sodium nitrates penetrate the protoplasm of 

 Spirogyra more rapidly than calcium nitrate, and potassium and sodium 

 chlorides more rapidly than calcium chloride. Potassium and sodium nitrates 

 penetrate more rapidly than the corresponding chlorides. The (final) order 

 of kation absorption by Spirogyra, according to Euhland, is therefore 

 [K, Na], Ca, and the order of anions : NO3, CI. 



Fitting (1) has recently followed the rate of intake of salts by the 

 epidermal cells of Blioeo discolor by following the rate of deplasmolysis in 

 hypertonic solutions. He records that potassium nitrate and chloride 

 penetrate the protoplasm with ease, but the rate of penetration of potassium 

 sulphate is much smaller. As regards kations, sodium nitrate and sodium 

 chloride both penetrate the protoplasm, but lithium chloride and lithium 

 nitrate are less permeable than potassium nitrate. Magnesium chloride, 

 nitrate and sulphate are only permeable in small degree, while in regard to 

 calcium chloride and calcium nitrate Fitting could observe no permeability. 

 The same applies to barium salts. 



The order found by Fitting is thus as follows : for kations [K, Na], Li, Mg, 

 [Ca, Ba] ; for anions [NO3, CI], SO4. 



Troendle (13) using the same method as Fitting on roots of Zupinus albus 

 and palisade cells of the leaves of Acer platanoides and Scdix labylonica, 

 finds various ions absorbed in the following order : kations, Eb, K, Na, Li, 

 Mg, Ba, Sr, Ca ; anions, ISTOs, CI, SO4. 



Pantanelli's researches, to which reference has been made earlier, extend 

 over a wide range of forms, including flowering plants (e.g., Cicer arietinum, 

 Vicia Faba), green algae (Valonia utricularis, Ulva lactuca), and a yeast 

 (Barbera Wine yeast). His results show that a considerable variation occurs 

 in different forms. "With higher plants, the absorption of calcium is 

 markedly less than that of potassium, while the rapidity of the absorption 

 of nitrate is clearly shown. With lower plants, on the other hand, calcium 

 is readily absorbed. Pantanelli's results bring out clearly the different rates 

 of absorption of the kation and anion of the same salt, but it is also clear 

 from comparison of the absorption of the same ion from different salts, that 

 the absorption of one ion is influenced by the other. For example, Cicer 

 arietinum absorbed 0-35 mgrm. of potassium from a 0-025 jST solution of 

 potassium chloride, while from a solution of potassium nitrate of the same 

 concentration 2-74 mgrm. of potassium were absorbed in the same time. 



VOL. xc. — B. 2 K 



