iwl 



BRIEFER ARTICLES 



149 



toxicity of the anions is negligible) by supposing that the sole poisonous 

 constituent is magnesium, whose toxic action is completely inhibited 

 by the calcium present. But on this view it is clear that the potassium 

 and iron are completely superfluous from the standpoint of a balanced 

 solution. Knop added them for nutrient, not for balancing, purposes, 

 nor is there reason to suppose that he was aware of antagonistic salt effects. 

 At the concentrations at which he worked these effects are not at all evi- 

 dent with such flowering plants as were used in his experiments. Under 

 these circumstances the discovery of antagonistic salt effects is very improb- 

 able. For most of the plants for which Knop's solution is employed at 

 its ordinary concentration, it is not a balanced solution, because its indi- 

 vidual components are not sufficiently toxic to require balancing. 



That to Professor Loew is due the very great credit of investigating 

 the antagonistic action of magnesium and calcium, and of making clear 



importance 



These and other inves- 



tigations made by him in the difficult and obscure field of the function of 

 the mineral salts are of the highest value. Together with the experiments 

 of other investigators they have thrown much light on antagonistic action. 



nasmuch, however, as Professor Loew apparently does not believe in 

 generalizing the principle of antagonistic action, as Professor Loeb has 



one m his theory of balanced solutions, but prefers to restrict it to the 

 ^gle case of Mg vs. Ca, I find myself quite unable to agree with him. 



n t e course of a series of experiments on wheat I have found antagonism 

 between each of the following pairs of salts: 



N H 4 vs. Ca 

 K vs. Ca 



Na vs. Ca 

 % vs. Ca 



NH 4 vs. Na 

 NH 4 vs. K 



Na vs. K 



Mg vs. K 

 Na vs. Ba 

 K vs. Ba 



Na vs. Sr 

 K vs. Sr 



Mg vs. Sr 



to 



rest 



xpected 



- — * w u Cai wun sucn a series ot tacts can narcny ue cApc^vx 



I ° pt a Vlew whicl * accounts for only one of these cases and ignores the 



' jJJ ex P lain s them as due to the formation of double salts, particularly 



an explanation is wholly untenable in view of the facts of dissocia- 



^such 

 tion. 



J- V. Osterhout, University of California, Berkeley. 



