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The Influence of External Concentration on the Position of the 

 Equilibrium attained in the Intake of Salts by Plant Cells. 

 By Walter Stiles, M.A., Lecturer in Botany in the University of Leeds, 

 and Franklin Kidd, M.A., D.Sc, Fellow of St. John's College, Cam- 

 bridge. 



(Communicated by Prof. Bayliss, F.R.S. Eeceived July 2, 1918.) 

 Introduction. 



The intake and translocation of dissolved substances in the living plant 

 present one of the outstanding problems of the physiology of nutrition, and 

 one which has for a long time attracted the attention of plant physiologists. 



We know the metallic or ash constituents of the plant are taken in by the 

 root in the form of salts, and eventually find their way, in some form or 

 another, to every part of the organism. What is the mechanism of their 

 intake and of their translocation from cell to cell ? Can the movement be 

 explained as a simple dififusion phenomenon, or are adsorption phenomena 

 concerned, or chemical combinations, or is the process still more complex ? 

 The work recorded in this paper forms a first instalment of an attempted 

 analysis of these phenomena of the intake and movement of salts in the 

 living plant. 



The experimental work which has so far been performed bearing directly 

 on our problem falls mainly into two well-defined groups. In one group the 

 imit of experiment has been the whole living plant, and the methods employed 

 have been those of pot-culture and particularly water-culture. Although this 

 method of attack resulted in the discovery of the fundamental principles of 

 plant nutrition, yet the results obtained by the waiter-culture method as 

 usually employed, although furnishing data in regard to the relationship 

 between the constitution of a solution external to the root and the resultant 

 growth, do not afford quantitative data as to the intake of salts. In the 

 absence of these quantitative data general laws for the relations of electro- 

 lytes to living tissue have consequently not been formulated. 



In the second group of experiments isolated cells or organs or pieces of 

 cell-tissue form the unit of experiment. In these cases the experimental 

 difficulties in obtaining quantitative data are considerably less than when the 

 whole plant is dealt with, and such data are consequently accumulating. 

 The work that forms the subject of this paper belongs to this second group, 

 and in the experiments here recorded the parts of the plant with which we 

 have dealt are storage organs. While it is true that the general tendency has 



