JlUS] Waynick: Antagonism and Cell Permeability 165 



metabolism. Forbes''- has likewise localized the effects of copper salts, 

 when present in toxic concentrations, and concludes that the toxic 

 effect of copper is due to the combination of metal with protein at 

 the growing tips of the roots. 



From the experimental results given in the present paper, it is 

 evident that the presence of the salts of each element in toxic concen- 

 tration results in an increased permeability of the plant tissues to 

 calcium and magnesium at least. Ruprecht's view that plants starve 

 for lack of nutrient salts when grown in toxic solutions is untenable, 

 in the light of the above discussion. 



The results of both investigators are significant in indicating the 

 localization of the effect of the two metals studied in the extreme 

 outer portion of the roots, in which the plasma membrane is located. 



The results obtained by Loeb with Fundulus eggs, by Osterhoul 

 with Laminaria, using electrical conductivity methods, and by Brooks 

 employing microscopical methods with various plant tissues, all point 

 to the preservation of normal permeability as the result of antago- 

 nistic salt action. The results reported by these investigators using 

 widely different methods have been confirmed in the present work by 

 the use of a more direct and more nearly quantitative method than 

 any hitherto employed. 



It must be recognized, however, that a picture of but one stage in 

 the growth of the plant has been given and that only a portion of the 

 inorganic constituents have been determined. The results reported 

 are essentially those of a static system and must be so considered in 

 comparing them with results obtained by the use of other methods 

 referred to above. 



Summary 



In the present paper results are given showing the effeel of vari- 

 ous salt solutions upon the chemical composition of plants, with spe- 

 cial reference to a correlation between toxic and antagonistic effects 

 and composition. A uniform nutrient solution was used throughout. 

 The cultures were arranged in series in which the concentration of 



one salt was kept constant while the concentration of a s md salt 



varied over a wide range. In several series the concentration of both 

 varied, but the ratio between the two remained constant. The ana- 

 lytical data cover the percentages of calcium and magnesium found 

 in the plants grown in every culture, together with determinations 



-Univ. Cat. Publ. A<jr. Sei., vol. 1 (1917), p. 395. 



