AUTHOR'S PREFACE 



A new period in the investigation of plant respiration began 

 with the opening of the twentieth century. The discovery of 

 cell free alcoholic fermentation, a process not accomplished by 

 purely chemical means, suggested that material transformations 

 which underlie normal plant respiration could possibly be 

 detached from the living substance. Soon after in fact, W. 

 Palladin and his coworkers as well as the author of this book 

 succeeded in proving for killed plants an enzymatic metabolism 

 completely analogous to oxygen respiration.^ This condition 

 meant, inasmuch as it was later estabHshed beyond doubt, that 

 the respiratory metabolism is not to be conceived as a resultant 

 of heterogenous reactions which take place in the protoplasm, 

 but as a chemical process which actually consists of inter- 

 mediate steps and which is always uniform. It is only in this 

 light that a chemical investigation of the material transforma- 

 tions which take place in respiration appears possible and 

 practical. For example, how could one raise even the first 

 basic questions of the respiratory material if respiration were 

 not an independent process? 



Even before the discovery of "cell free respiration" the 

 author of this book developed a new theory of the genetic 

 connection of oxygen respiration with alcoholic fermentation, a 

 theory which is in accord with modern conceptions and which 

 could serve as a working hypothesis in investigations of the 

 chemical nature of plant respiration. 



The above mentioned favorable instances have ushered in 

 a comprehensive biochemical study of plant respiration. 

 Previously the chief consideration had been only the biological 

 side of respiration and the influence of external factors, this 

 came about only because, as was previously noted, no proof 



'The first publication on the cell free oxygen respiration of aerobic plants was: 

 Kostytschew, S. Uber Atmungsenzyme der Schimmelpilze. Ber. d. bot. Ges. 22: 207. 

 1904; also Maximow, N. Ibid., p. 323- 



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