JLfA,' 



Equilibrium in the Intake of Salts by Plant Cells. ^ 0^^^69 



4. Carrot tissue absorbs potassium, sodium, and calcium chlorides in all 

 concentrations examined. In the case of each salt, absorption is at first 

 approximately proportional to the external concentration, but this relation is 

 not continued with time, as the absorption progresses towards an equilibrium 

 condition in which the ratio of internal to external concentration is not 

 constant, but varies with the concentration. Similar results are obtained 

 with potato. 



5. The ratio of final internal to final external concentration has been 

 called the absorption ratio. With low external concentrations it is many- 

 times unity, but with increasing concentration it diminishes, reaching with 

 higher strengths of solutions a value considerably less than unity. 



6. The relation between the final internal concentrations and the final 

 external concentrations is given by the equation y = A;c"\ where y is the final 

 internal concentration and c the final external concentration. This is the 

 adsorption equation, but the data presented are regarded as inadequate in 

 themselves to justify the conclusion that absorption of salts by the cell is an 

 adsorption process, and no proposals are put forward as to the mechanism of 

 salt intake by the cell. 



7. The results obtained ^re correlated with those of other workers on salt 

 intake by plant tissue, especially those of Nathansohn, Meurer, and Euhland 

 in regard to salt intake as measured by direct chemical analysis, and those of 

 Fitting and Troendle dealing with the absorption of salts from hypertonic 

 solutions as studied by the plasmolytic method. 



LITERATURE CITED, 



{!) Bayliss, W, M. ' Principles of General Physiology.' London, 1915. Second 

 edition, 1918. 



(2) Fitting, H. " Untersuchungen iiberdie Aufnahme von Salzen in die lebende Zelle." 



. ' Jahrb. Wiss. Bot.,' vol. 56 (PfefFer-Festchrift), pp. 1-64 (1915), 



(3) Meurer, R. " Uber die regulatorische Aufnahme anorganischen Stoffe durch die 



Wurzeln von Beta vulgaris und Daucus Carota," 'Jahrb. Wiss. Bot.,' vol. 46, 

 pp. 503-567 (1909). 



(4) Moore, B., and Roaf, H. E. " Direct Measurements of the Osmotic Pressure of 



certain Colloids," ' Biochem. Journ.,' vol. 2, pp. 34-73 (1907). 



(5) Moore, B., Roaf, H. E., and Webster^ T. A. " Direct Measurement of the Osmotic 



Pressure of Casein in Alkaline Solution. Experimental Proof that apparent 

 Impermeability of a Membrane to Ions is not due to the Properties of the 

 Membrane but to the Colloid contained within the Membrane," ' Biochem, Journ.,' 

 vol. 6, pp. 110-126 (1912). 



(6) Nathansohn, A. " Ueber Regulationserscheinungen im StofFaustausch," ' Jahrb, 



Wiss. Bot.,' vol. 38, pp. 249-290 (1903). 



(7) . Nathansohn, A. " XJeber die Regulation der Aufnahme anorganischen Salze durch 



die Knollen von Dahlia," ' Jahrb. Wiss. Bot.,' vol. 39, pp, 607-644 (1904). 

 VOL. XC. — B, 2 P 



