v iii A NOTE OF APPRECIATION 



Palladin's lectures were always precise and unusually clear. His text-books 

 —on plant anatomy, plant physiology, and systematic botany— show his excel- 

 lent style of presentation. In his teaching positions Palladin always attracted 

 a group of enthusiastic students. He was a calm and polished leader, always 

 pleasant to work with, who would not quarrel over unessential matters but 

 who understood how to lead the advance persistently toward the finer and 

 greater things. The remarkable precision of his scientific thinking, together 

 with his indefatigable application, placed him at the head of a school of plant 

 physiology that extends far beyond the boundaries of Russia. 



Although he was interested in and contributed to many different lines of 

 botanical study, Palladin's main research publications were, from the time of 

 his master's-degree dissertation at Moscow, devoted to the fundamental phe- 

 nomena of respiration. His many papers on this subject — and those that 

 appeared under joint authorship, with one or more of his colleagues or students 

 —were not confined to the Russian language, and Palladin's name became 

 familiar to readers of the leading French and German journals devoted to 

 botany and to physiological chemistry. To the scientific world at large, as 

 well as to plant physiologists of all nations Palladin's thorough elucidation of 

 some of the most fundamental and baffling aspects of the respiration process 

 will stand as his greatest achievement. Step by step, he and his followers 

 gradually built up a new and clear picture of the chemistry of respiration as it 

 apparently occurs in all living cells. 



The main points of the Palladin theory of respiration are somewhat as 

 follows: Under the influence of enzymes, carbohydrates and similar sub- 

 stances are anaerobically decomposed into carbon dioxide and incompletely 

 oxidized organic compounds, these partial oxidations occurring partly at the 

 expense of oxygen derived from the decomposition of water. The hydrogen 

 produced by aqueous decomposition may sometimes be set free, or it may dis- 

 appear in the reduction of some of the incompletely oxidized compounds just 

 mentioned, but it is regularly oxidized in aerobic respiration, with the formation 

 of water. The aerobic oxidation of hydrogen occurs by two stages: (i) This 

 element combines with respiration pigments (acceptors of hydrogen), thus 

 forming respiration chromogens. (2) The chromogens, in turn, are oxidized by 

 free oxygen, under the influence of oxidizing enzymes, forming water and respira- 

 tion pigments. Thus, in normal, or aerobic, respiration, the carbon dioxide 

 produced is a product of anaerobic respiration (fermentation), while the water 

 produced is a product of the oxidation, by free oxygen, of anaerobically pro- 

 duced hydrogen. Anaerobic respiration occurs in all living cells, of animals as 

 well as plants, while aerobic respiration is confined to those forms that are sup- 

 plied with free oxygen and possess adequate oxidizing enzymes. This theory, 

 with all the details that it implies, must be regarded as one of the most bril- 

 liant achievements of physiological science, and it may be said to represent 

 the main contribution Palladin made to the advance of appreciative human 



