New York Agricultural Experiment Station. 235 



largely provided with soda. It is, then, an acknowledged fact 

 that soda cannot take the place of potash." 



Oscar Loew' states that: "The paramount importance of 

 potassium salts for every living cell is firmly established. ♦ ♦ * 

 These salts can never be replaced by lithium or sodium salts, 

 but in certain fungi they may be replaced to a limited extent 

 by rubidium or caesium 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 func- 

 tions to perform in plant life. * ♦ ♦ Nevertheless, sodium 

 salts may sometimes exert a beneficial action, and several observ- 

 ers ascribe to them a promoting action in the ripening process 

 of the Graminese." * ♦ ♦ 



In regard to rubidium chloride be sums up some experiments 

 as follows: "These experiments proved that it is impossible to 

 raise normal seed-bearing buckwheat plants when the potassium 

 chloride in the culture solution is replaced by rubidium 

 chloride, but on the other hand they left hardly any doubt that 

 rubidium chloride can serve for certain physiological functions 

 of which sodium chloride is utterly incapable. With rubidium 

 chloride, buckwheat plants may reach a dry weight of even 

 thirty-seven times that of the seeds, but with sodium chloride 

 they seldom reach over five times. In a normally raised plant, 

 however, the dry matter may be over six hundred times the 

 weight of the seed." 



A. Atterberg^ carried on experiments with sodium. The fact 

 that sodium is a common constituent of the ash of plants, led 

 the author to test the question whether this element might not 

 be capable of replacing in part other similar plant constituents, 

 especially potash. Two series of experiments were made with 

 black Tartarian oats, grown in pots filled with quartz sand and 

 watered with nutritive solutions containing soluble plant food. 

 Different amounts of potassium were replaced by like amounts 



'U. S. Dept. Agr., Div. of Veg. Phys. and Path, Bui. 18. 

 'Sodium as a Plant Nutrient. Deut. landw. Presse., 1881, p. 1035, ab- 

 stracted Exp. Sta. Rec, 3 : 554. 



