468 Mr. W. Stiles and Dr. F. Kidd. Position of the 



take place between the salts used and some constituent or constituents of 

 the living cells, so that either definite chemical compounds are produced, or 

 adsorption compounds are foniied. 



The results obtained in regard to the influence of concentration on the 

 absorption ratio conform to the adsorption equation. Obviously our results 

 could be interpreted on the view that the intake of salts by the cell is simply 

 an adsorption process, as advocated by Moore and his collaborators (4, 6), 

 but it would also be possible to explain them on the basis of the formation 

 of non-diffusible substances inside the cell in conjunction with changes 

 in permeability of the cell which might result owing to the presence of the 

 salt. Into a consideration of these questions we do not propose to enter 

 further here. We may, however, point out that the behaviour of the treated 

 tissues when removed from salt solution and put into distilled water suggests 

 that the processes concerned in the intake of salts are to some extent 

 reversible. In so transferring the treated tissues to distilled water, exosmosis 

 occurs varying in amount according to the concentration of the solution 

 previously used, and when the assumption is made that the exosmosis is 

 mainly one of salt previously absorbed, it is found that the ratio of internal 

 concentration to external concentration bears the same sort of relation to 

 final external concentration as the absorption ratios. For any external con- 

 centration the ratio of internal to external concentration is now higher than 

 that observed in the case of absorption ratios. These facts again make us 

 hesitate to draw definite conclusions from the apparent conformity of the 

 absorption results to the adsorption equation. 



The influence of composition of the salt on its absorption will be dealt with 

 in a further paper. 



Summary. 



1. The course of intake of salts by carrot and potato tissue has been 

 followed by measuring the changes in conductivity of the solution of salt 

 presented to the tissue. Concentrations of each salt were employed, varying 

 from N/10 to N/5000. 



2. In the case of copper sulphate, exosmosis exceeds absorption in all 

 concentrations of copper sulphate. This is characteristic of toxic substances. 

 The initial rate of exosmosis increases with increase of concentration of the 

 toxic solution. 



3. The exosmosis from carrot into distilled water is slight, while that from 

 potato is considerable. For this reason carrot is a much more suitable 

 subject for following absorption by the conductivity method than potato, 

 where the absorption of salt is masked by the exosmosis of electrolytes from 

 the tissue. 



