April, 1907.] LOEW & ASO.— ON PHYSIOL. BALANCED SOLUTIONS. 79 



stitution of its potassium by magnesium would not lead to a 

 collapse of the tectonic, as is the case of the calcium-protein 

 compound of the nucleus when its calcium is replaced by 

 magnesium. Further, that hypothesis would necessarily imply 

 that calcium salts must also act poisonously, which is not 

 the case. The alga: cells showed even much starch after 2 

 months in a 0.2^ solution of CaCl 2 . 



It is much more probable that the retardation of the toxic 

 action of Mg-salts by K-salts is due to the property of forming 

 double salts with potassium. These double salts may exert 

 less energy in a similar way as also Mg-bicarbonate exerts less 

 toxical energy on Spirogyra than many other Mg-salts do. a) It 

 is stated (of Muspratt's Chemistry) that a very stable double 

 salt is formed by both the sulphates of Mg and K, but not by 

 those of Mg. and Na. 2 ' This would explain, why the algae live 

 longer in the mixture of Mg and K sulphates than in that of 

 the nitrates or chlorids ; in the latter cases so well defined 

 double salts as with the sulphates have not been obtained but 

 the existence in the solutions of the mixture is more probable 

 than for the mixture of magnesium and sodium salts. 



Still another hypothesis may be considered which however 

 does not exclude the former. It is possible that potassium 

 salts can attach themselves to the calciumproteincompounds 

 of nucleus and chloroplast and thus rendering the calcium more 

 negative diminish its faculty to be substituted by magnesium. 

 Further investigations are necessary . 3; So much follows from 

 our various experiments with water and soil cultures that the 



D We have observed that magnesium-potassium sulphate acts on calcium carbonate 

 at 90° much more slowly than magnesium sulphate alone does. 



2) A double salt of Mg and JSa-sulphate can only be obtained in presence of much 

 MgCl 2 , but as soon as the double salt is treated with water, it undergoes a splitting 

 into the two simple sulphates. --In coincidanee therewith is the fact that sodium 

 sulphate cannot essentially (a few days only) retard the toxic action of magnesium 

 sulphate for Spirogyra. 



3 > In comparing the peculiarity observed in the mixture of KCl + MgCI 2 (see 

 table), that the cytoplasm can remain alive long after the death of nucleus (and 

 chloroplast) it seems probable that potassium sahs can also increase the resistance power 

 of the cytoplasm to disturbing influences in the cell. 



