Hoagland — 144 — Plant Nutrition 



cumulation, at least reflects a vital activity of living 

 cells indispensable to the accumulation of salt in the 

 sense indicated above. Protein synthesis is evidently 

 not essential to certain types of salt accumulation, since 

 Steward and Preston showed that from solutions 

 containing bicarbonate, at relatively high pH, potas- 

 sium could be accumulated, with the formation of 

 organic acid, although evidence for protein synthesis 

 was lacking. Accumulation of bromide, however, was 

 suppressed. Possibly interrelations of bromide and 

 bicarbonate ions in the absorption process were in 

 part responsible for the latter effect. 



In the studies of Steward and Preston on aerated 

 discs of potato tuber accumulating both cations and 

 anions of the salt presented (KBr), protein synthesis 

 took place at the expense principally of amino-acid 

 nitrogen other than that of asparagine or glutamine, 

 although an unstable glutamine-like compound may be 

 a reactive intermediary between stable reserves of 

 amino acid nitrogen and proteins. An important con- 

 clusion of these experiments is that in the potato 

 tuber tissue low respiration is associated with low 

 protein synthesis and highest protein synthesis with 

 highest respiration. Thus there are linked together 

 protein synthesis, respiration, and salt accumulation. 

 Potassium and calcium salts had opposed effects on 

 the synthesis of protein and on respiration. The for- 

 mer accelerated, and the latter retarded these proc- 

 esses, at .075 molar concentrations. The full explana- 

 tion awaits further investigation, but it may be of 

 interest that some anions are absorbed more rapidly 

 than calcium ions and effects of unequal ion absorp- 

 tion complicate the study of metabolic responses to 

 calcium salts. 



The excised low-salt, high-sugar, young roots of 

 barley plants, which possess for a time an extremely 

 high capacity for accumulation of both cations and 

 anions from solutions of certain potassium salts, do 

 not yield obvious evidence that growth processes and 



