T. C. Broyer 227 



continued accumulation. Such did not seem to be significant in short 

 time studies with excised barley roots, where amino and amide nitrogen 

 in sap were measured (84, S5). A general correlation has been shown 

 for various types of tissues between the accumulation of inorganic 

 solute and their general metabolic level as measured by respiratory 

 activity. This relation is shown in Table VIII (/6). Certainly, high 

 absorption or accumulation rates for inorganic solute must, in some 



TABLE VIII 



Relationship Between Respiration Intensity and Salt Accumulation by 

 Certain Cells from Various Plant Species. — Collander (/6) 



*Calculated from the C0 2 liberated 



way, require the expenditure of energy by cells. A causal relationship 

 has been sought, therefore, between the enhanced respiration in the 

 presence of a salt supply and the accumulation of inorganic solute in 

 cells. 



Organic acids and respiratory quotient 



In certain cases of metabolic accumulation, an approximate equiva- 

 lence in movement of anion and cation into roots is observed. However, 

 this is not generally the rule from single salt media. More frequently 

 there is an excess migration of one ion over the other, apart from 

 certain limited ionic exchanges. When this occurs, there is evidently 

 an adjustment within the plant such that ionic equivalence therein is 

 maintained. Organic acids appear to play a role in this regard. When 

 the rate of cation influx is more rapid than anion, organic acid anions 



