T. C. Broyer 205 



the Q 10 values for both absorption and respiration are very similar in 

 magnitude for like increases of io° C. These vary from 2 to 3 at lower 

 temperature intervals to about 1.5 at the higher. The respiratory quo- 

 tient does not vary significantly over the temperature range studied; 

 similar 10 values are obtained for both oxygen involved and carbon 

 dioxide evolved. The Q 10 values for absorption of bromide are con- 

 sistently above those for potassium over similar temperature ranges, 

 the difference decreasing with increase of temperature. If any significant 

 inward migration of potassium by exchange over that between anions 

 is possible, this should tend to bring the Q 10 values for potassium, com- 

 pared with bromide, closer together (see later discussion on "anion" 

 respiration). 



330 



Figure ir. Effects of temperature and nature of the culture medium on 

 the rate of outward movement of radioactive potassium from abscised bar- 

 ley roots which had previously accumulated radioactive potassium. Plants 

 4 weeks old. Set A: 0.005/V nonradioactive KC1 at 20.0 ° C; set B: 0.005N 

 nonradioactive KCi at i.o° C; set C: distilled water at i.o° C; set D: dis- 

 tilled water at 20.0 C. 



