T. C. Br oyer 221 



sarily involving other modes of movement. From data such as those 

 presented in Table VI (32), the marked reduction of the inward migra- 

 tion rate for potassium bromide with lowered temperature is clear. 

 The pronounced effect of deficient aeration in reducing the rate of 

 accumulation of inorganic solute from solutions of low concentration 



TABLE VI 



Effects of Aeration, Temperature, and Cyanide Treatments on Salt Movement 



into Excised Roots of Barley 



Net Respira- 



Experimental Conditions Absorption tion Rate 



K Br 



mg. C0 2 / 



m.e./l. sap g-/hr. 

 Experiment A 



H 2 0, air — 1.6 o 0.29 



H 2 0, N 2 — 5.1 o 0.16 



KBr 5 m.e., air 29.1 22.3 0.32 



KBr 5 m.e., N 2 — 0.1 3.2 0.12 



KBr 5 m.e. + KCN 1 m.e., air ... — 2.5 o o. 19 



KBr 50 m.e. + KCN 1 m.e., air . . 4.2 6.8 — 



Control roots (initial status) 24 o 



Experiment B 



KBr 60 m.e., 0.75 C, air 18.5 16.1 



KBr 60 m.e., 0.75 C, N 2 5.8 9.7 



KBr 60 m.e., 18. 5 C, air 58.4 50.0 



KBr 60 m.e., 18.5 C, N 2 7.2 10.7 



Control roots (initial status) ... 22.0 o 



Note: Experiment A: plants 3-4 weeks old; experimental period 8 hours, temperature about 

 20 C. Experiment B: plants 3 weeks old; experimental period 12 hours, temperature 18.5 C. 



was pointed out under discussion of environmental factors and ex- 

 emplified by the data in Figures <SA and 8B. A similar result is shown 

 with corresponding treatments in Table VI where the data also show 

 the greatly decreased rate of penetration of potassium bromide into 

 roots subjected to lowered temperature where diffusion may account 

 for the movement. Studies of this sort have been extended to include 

 the influences of certain respiratory inhibitors. Cyanide treatment, for 



