Equilibrium in the Intake of Salts by Plant Cells. 467 



to Fitting's, but he states them more precisely. His conclusion is that the 

 rate of absorption of the salt remains unaltered for the first few minutes (ten 

 in the case of sodium and potassium chlorides), after which it falls off with 

 time according to a logarithmic relation where the amount absorbed is pro- 

 portional to the logarithm of the time; Troendle, on the basis of these 

 results, puts forward the hypothesis that salt irritates the protoplasm which 

 responds by transporting salt to its interior. This produces changes in the 

 protoplasm which are of the nature of fatigue, and which increase with time 

 according to the Weber-Fechner law. 



That the absorption of salt should take place in proportion to the logarithm 

 of the time seems to us a totally inadequate ground for putting forward such 

 a definite theory of salt intake. Moreover, it is not at all clear to us that 

 Troendle's conclusions as to the course of salt intake are justified. As far as 

 we can follow the plasmolytic method of measuring salt absorption as 

 described by Troendle, it would appear that any possible effect of the external 

 concentration of the salt in influencing the rate of salt absorption is neglected, 

 and each one of his curves appears, as far as we can judge from the data 

 presented, to be constructed from numbers obtained with a whole range of 

 external concentrations. The results we record in this paper show that 

 "under the conditions of our experiment the external concentration has a great 

 influence on the rate of salt intake, and it ought certainly not to be assumed 

 that external concentration is without influence on the rate of salt absorption 

 although, of course, we do not know without experiment whether this is the 

 case or not with hypertonic solutions and plasmolysed cells. 



Considering now the influence of concentration on the absorption of salts, 

 an examination of the figures in Tables I-III, and the curves in fig. 1, 

 show that the initial rate of absorption is approximately proportional to the 

 concentration of the external solution. This relation is, however, not long 

 maintained owing to the proportionately greater accumulation of salt in the 

 tissue in absorption from dilute solutions. From weak external solutions 

 the salts not only freely enter the tissues but are accumulated there, so that 

 the internal concentration is very much higher than the external. As the 

 external concentrations are increased this heaping up of salt in the tissue at 

 equilibrium is proportionately less until at a certain concentration no more 

 than equal distribution inside and outside the tissue results, while in con- 

 centrations higher than this, concentration inside the tissue at equilibrium is 

 less than that outside. Our results with these higher concentrations agree 

 with those of Nathan sohn and Meurer. 



These facts show that the absorption of salts by the tissue used cannot 

 be explained simply by diffusion. The results suggest that combinations 



