1 60 RESPIRATION 



apple has been mentioned on an earlier page ; they found that 

 at a temperature of 22° C, the rate of respiration followed a 

 certain definite course. Parija found that in general a long 

 period in an atmosphere of nitrogen has no permanent effect 

 on metabolism, for when the apple is replaced in air, the rate 

 of respiration returns to that level of intensity it would have 

 attained in aerobic conditions in the same period of time. 

 This recovery of position may take two days and may be as- 

 sociated with a temporary phase of very low production of 

 carbon dioxide. On the other hand, transference from aero- 

 bic to anaerobic conditions is accompanied by a short transi- 

 tion phase. Thus on plotting the experimental results, two 

 types of anaerobic respiration are demonstrated. In the one 

 there is an initial outburst of carbon dioxide when the apple 

 is placed in nitrogen, the curve then drops and coincides with 

 the line of normal respiration in air ; after a time it gradually 

 descends below this line of normal respiration. When the 

 apple is replaced in air, the respiration curve fluctuates and 

 ultimately coincides with the normal aerobic curve. The 

 other type shows the same early burst of carbon dioxide fol- 

 lowed by a fall, but the curve remains above the normal 

 aerobic curve. When the apple is replaced in air, there is 

 a depression to below the normal line, followed by a gradual 

 rise leading to coincidence with the curve of respiration in air. 



The main conclusion drawn from this comparative study 

 is that the metabolic factors which determine the progress of 

 respiration with time are different for the aerobic and anaerobic 

 conditions. A consideration of these facts has led to certain 

 generalizations which will be dealt with later. 



Comparison of anaerobic respiration with the alcoholic 

 fermentation of sugar is an obvious pursuit and the two 

 phenomena show remarkable resemblances. The occurrence 

 of acetic aldehyde in respiring poplar buds was observed by 

 Godlewski and Polzeniusz.* Neuberg and Gottschalk f ger- 

 minated seeds of pea and of bean, previously sterilized by 



* Godlewski and Polzeniusz: " Zeit. physiol. Chem.," 1913, 83, 105. 

 t Neuberg and Gottschalk : " Biochem. Zeit.," 1924, I5'» l6 7 '• I0 - 2 5. 

 160, 256. 



