30 PHYSIOLOGICAL EOLE OF MINERAL NUTRIENTS. 



to 17 and for the Legurninosa? as 1 to 23. Hornbergers investiga- 

 tions a on the growth of maize showed the relation between potash 6 

 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, 

 1-6.8 to 1-12.2. 



BENEFICIAL ACTION OF SODIUM SALTS UPON PLANTS. 



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

 in the absence of sodium salts proves that the latter have no indispen- 

 sable function to perform in plant life. Stahl-Schroeder 6 ' 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 potassium which relates to the formation of organic substances in 

 plants. Nevertheless, sodium salts may sometimes exert a beneficial 

 action, and several observers ascribe to them a promoting actionin 

 the ripening process of the Gramineae. It is claimed that sodium 

 nitrate yields up its nitrogen to the plant much more readily than 

 does potassium nitrate. 



Wagner and Wolff have each reported favorably 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 d 

 pointed out the beneficial action of sodium salts upon wheat. How- 

 ever, further control experiments along this line will be necessary/ 



NECESSITY OF SODIUM SALTS FOR ANIMALS. 



The great amount of sodium chlorid in the blood has already been 

 mentioned, but the blood contains still other sodium salts of impor- 

 tance, such as sodium bicarbonate (in the ash of ox blood was found 

 14 to IS per cent sodium carbonate) and the secondary sodium phos- 

 phate. Both these salts have an important bearing on the respiration 

 process, as they carry in solution to the lungs for exhalation the car- 

 bonic acid produced by even the most remote cells of the body. 

 ^According to Bunge, cartilage is especially rich in sodium compounds. 



«Landw. Jahrb., Vol. XI, p. 461. 



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

 quently it is only the yield of straw that is increased. The form in which the potas- 

 sium salts are given exerts much influence. 



c Jour. f. Landw., Vol. XLVII, p. 78. 



d Revue Generale de Botanique, 1898, Vol. X. He states also that "potassium 

 silicate produces a dark-green color." 



e Copeland found that in plants potassium salts produce a greater turgor than do 

 sodium salts. McKenney observed with luminous bacteria that either sodium or 

 magnesium is required for light production. Potassium, ammonium, lithium, rubid- 

 ium, calcium, barium, and strontium can not replace sodium (or magnesium). 



