44 SOIL CONDITIONS AND PLANT GROWTH 



TABLE XX. EFFECT ON VARIOUS SALTS IN REDUCING THE TOXICITY OF MgSO 4 . 

 KEARNEY AND CAMERON (147). 



Hansteen (see 214) found that the toxic effect of potassium salts 

 used singly was overcome even when so little lime was added that 



the ratio -? = L Osterhout found (223) that Vancheria sessilis 

 K 2 U 840. 



lived for three weeks in distilled water, but was killed in a few minutes 

 by _ L N NaCl, and in a few days by -oooi N NaCl ; yet the toxic effect 



even of the stronger solution disappeared on adding one gram-molecule 

 of CaCl 2 for every 100 gram-molecules of NaCl. Magnesium chloride 

 and sulphate, potassium chloride and calcium chloride were also toxic 

 when used singly, but in admixture they formed a nutrient medium in 



which the plant grew normally and developed fruit even when i, 



32 

 N NaCl was also present. 



It is also found that calcium and magnesium ions diffuse out from 

 the plant cell more rapidly into solutions of single sodium or potassium 

 salts than into pure water and very much more rapidly than into solu- 

 tions of calcium salts. Niklewski (214) found the amounts of CaO and 

 of MgO diffusing out of cut pieces of beet to be : 



These facts can be explained on Loeb's theory (179) that life 

 phenomena depend upon a balanced adjustment between a number of 

 "metal proteids " in the tissues, i.e., compounds of proteins with cal- 

 cium, magnesium, sodium, etc. If the circumambient solution contains 

 only one of these metallic ions it must soon displace others in the tissues 

 and upset the balance with fatal consequences. 



Other facts are less easy to explain, such as Grafe and Portheim's 



