23 



is more potassa in seeds which are richer in protein, but the proportions 

 do not show any very close relation. For the Graminea^ the proportion 

 of potassa to protein would be as 1 to 17, and for the Leguminosa3 as 1 

 to 23. Hornberger's investigations ^ on the growth of maize showed the 

 relation between potassa and protein nitrogen in the different periods 

 of plant development to be for the leaves 1-1.1 to 1-1.8, or calculating 

 from the protein itself, 1-G.8 to 1-12.2. 



Although potassa is indispensable in the formation of carbohydrates, 

 the quantitative proportions in the seeds show a closer relation to the 

 protein than to the starch content of the seeds.^ 



BENEFICIAL ACTION OF SODIUM SALTS. 



The fact that many kinds of plants have been raised to perfection in 

 the absence of sodium salts proves that the latter have no indispensable 

 function to perform in plant life. Stahl-Schroeder ^ recently inferred 

 from his experiments what others also had already observed, that is, 

 that sodium can not perform the special part of the functions of potas- 

 sium which relates to the preparation of organic substances in plants. 

 Nevertheless, sodium salts may sometimes exert a beneficial action, and 

 several observers ascribe to them a promoting action in the ripening 

 process of the Graminese. Wagner and Wolff have each reported favor- 

 ably on the application of sodium salts, pointing out that as regards 

 osmotic and neutralizing functions a replacement of potassium by sodium 

 compounds is quite possible, which is of practical value, since the sodium 

 salts are much cheaper than the potassium salts. In a recent article 

 Dassonville* pointed out the beneficial action of sodium salts upon 

 wheat. However, further control experiments along this line will be 

 necessary. 



CAN POTASSIUM SALTS BE REPLACED BY RUBIDIUM SALTS IN GREEN 

 PLANTS AND IN ANIMALS? 



Various authors have shown that potassium can not be replaced in 

 plants by sodium or by lithium, starvation phenomena occurring with 

 the former and toxical i3henomena developing with the latter (Nobbe). 

 As regards their atomic weight, sodium and lithium stand below while 

 rubidium and csesium stand above potassium, as follows: 

 Li = 7 



Na= 23 ldiff.:16 



K = 39 diff.: 16 



Eb= 85.4 diff.: 16 x 3-1.6 



Ci =133 diff.: 16 x 3 -0.4 



'Landw. Jahrb., Vol. XI, p. 461. 



-Fertilizing with potassium salts does not always increase the yield of grain. 

 Frequently it is only the yield of straw that is increased. The form in which the 

 potassium salts are given exerts much influence. 



Mour. f. Landw., Vol. XLVII, p. 78. 



■* Revue G6n6rale de Botanique, 1898, Vol. X. He states also that "potassium 

 silicate produces a dark green color." 



