COMPARATIVE STUDIES ON RESPIRATION. 



XI. The Effect oe Hydrogen Ion Concentration on the 

 Respiration of Penicillium chrysogenum. 



By F. G. GUSTAFSON. 

 (From the Laboratory of Plant Physiology, Harvard University, Cambridge.) 



(Received for publication, May 28, 1920.) 



The effect of hydrogen ion concentration on respiration has re- 

 ceived very little attention. Warburg^ measured the amount of 

 oxygen consumed by fertilized eggs of Slrongylocentrotus lividus, 

 when they were in a balanced solution of NaCl, KCl, and CaCl2. 

 He found that on raising the hydrogen ion concentration from pH 8 

 (which is that of sea water) to pH 6 the oxygen consumption was 

 lowered to nearly one- third, while on lowering the hydrogen ion 

 concentration to pH 11 the oxygen consumption was more than 

 doubled. Loeb and Wasteneys^ repeated Warburg's experiments, 

 using Arhacia punctulata. They found that if oxygen consumption 

 at an OH ion concentration of 10~^ (pH 7) is taken as 1.00, at a 

 concentration of 10~^ (pH 10) it was 1.17 and at a concentration of 

 8.4 X 10-" (pH 10.92) it was 2.74. Since similar concentrations of 

 NaOH and NH4OH produced similar effects it appeared doubtful 

 whether the result was to be attributed to the concentration of hy- 

 droxy! ions only. 



Thunberg,' studying the effect of H ions on surviving frog muscles, 

 found that with concentrations of 0.005 m HCl (about pH 2.3) the 

 production of CO2 decreased to 82.7 per cent of the normal, 0.02 

 M HCl (about pH 1.7) decreased it to 44.6 per cent while with 0.05 m 

 HCl (about pH 1.2) there was a decrease to 24 per cent of the nor- 

 mal. He found the same concentrations of NaOH less toxic; 0.005 



^ Warburg, 0., Z. physiol. Cheni., 1910, \xv\, 305. 

 "Loeb, J., and Wasteneys, H., Biochem. Z., 1911, xxxvii, 410. 

 ^Thunberg, T., Skand. Arch. Physiol, 1910, xxiii, 154; 1911, xxiv, 23. 



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