( 706 ) 



.* n,(i(i5 



0,001 



be shifted by adding other compounds to the solution. This is indeed 

 often the case, and so the weighing-method lends itself to a repeti- 

 tion of the experiments of Kahlenberg and True ^) and those of 

 True and Gies ^) in which bj a different method the toxicity of 

 metallic compounds was proved to be diminished by the addition of 

 certain salts. The case which I have examined a little more closely 

 does not concern a metallic poison, however, but an alkaloid. 



The lowest poisonous concentration of chinine hydrochloride for 

 potato is a very low one, namely 0.001 grammol. per litre ^), the 

 action lasting 24 hours. All parts of plants which I examined, proved 

 to be about equally sensitive to this poison. The result of adding 

 NaCl in a certain concentration to the chinine solution, is that after 

 the same time, death occurs at a considerably higher concentration 



of the chinine, this concentration 

 depending again on the amount 

 of NaCl in the solution. The figure 

 represents graphically^ this shifting 

 of the toxic limit. One sees from 

 it that by 0.2 grammol. NaCI per 

 litre the harmful concentration of 

 the chinine hydrochloride is raised 

 from 0.001 to 0.005 grammol., 

 a further addition of salt acting 

 less favourably again. At 0.4 gram- 

 mol., as was pointed out before, 

 pure NaCl is injurious to the potato. 

 As far as I have been able to gather, the toxic action of chinine 

 hydrochloride on plants generally is modified in the same sense by 

 Na CI. At any rate I obtained the same results with pieces of sugar- 

 beetroot, the leaf-stalk of Begonia, fragments of the leaves of Aloe. 

 As the cells of the sugar-beetroot resist much higher concentrations 

 of common salt than those of the potato, it is not surprising that 

 also in the presence of more than 1 grammol. Na CI per liter the 

 antagonistic action towards chinine can be observed with this plant. 

 The diminution of toxicity, observed by the above-mentioned 

 authors when certain salts, harmless in themselves, are added to 

 metallic compounds, has been ascribed in most cases to the concentration 

 of toxic ions being decreased; their results agree with the connection 



0,001 



0,1 



0,2 



0,:5 



0,1 

 NaCl 



1) Botan. Gazette, vol. 22, 1896. 



2) Bulletin Torrey Botan. Club. vol. 30. 1903. 



3) or 0,03965 "/o ; mol. weight of G20 H24 No O2. HGl + 2 HgO = 396,5. 



