THEORETICAL CONSIDERATIONS 265 



the fourth step. Possibly, in the Hght of Slator's work, the radium 

 experiments are to be interpreted as showing acceleration, not of fer- 

 mentation itself, but only of the metabolism and growth of the 

 ferment-organism. 



Here, as always, the living matter, or the biogen molecule, the 

 rate of its construction and decomposition, or of its formation of 

 enzymes or other substances, must always be considered as a possi- 

 ble, and I believe as a very probable and essential factor, delicately 

 sensitive on account of its extreme lability, to the changes of energy 

 produced by the rays. Further w^ork may demonstrate that fer- 

 mentation by unorganized ferments may be capable of modification 

 by radium rays, but this would not in the slightest degree argue 

 against the hypothesis that, with living yeast, the effects are due, in 

 part at least, to the direct influence of the rays on the living matter. 

 The most probable truth is that the rays influence both the vital and 

 the non-vital steps in the process. 



Respiration : Respiration is no longer considered a simple 

 oxidation, but as a series of both vital and non-vital processes begin- 

 ning with atomic changes within the protoplast, and terminating with 

 the evolution of carbon dioxide, or, in anaerobic respiration, of carbon 

 dioxide and ethyl alcohol. 



Since the publication, in 1876, of I^asteur's^* classic Aiudes sur 

 la btere, it has been customary to regard respiration and anaerobic 

 respiration as essentially alike. The correctness of this view was 

 more fully established by the researches of Stoklasa and Czerny,^''' ^"^ 

 and Stoklasa ^^'^* also showed that, in last analysis, normal, aerobic, 

 as well as anaerobic respiration, was of the nature of fermentation. 

 According to this author, an enzyme similar to Buchner's zymase of 

 yeast occurs in the cells of higher and lower plants, in the case of 

 both normal and aerobic respiration. It is secreted by living proto- 

 plasm. Plant cells contain, in addition to an enzyme that produces 

 alcoholic fermentation, one which causes the fermentation of lactic 

 acid. Aerobic respiration he considers as a secondary process.* 

 The primary process is the motion of the atoms in the " living mole- 



* Kostytschew ^' takes issue with the results reported by Stoklasa, and says, among 

 other things (p. 215), that it is premature to regard anaerobic respiration as a first step 

 in aerobic respiration. 



Ideas quite similar to those of Stoklasa were presented in 1905 by Barnes,^* who 

 proposed the term e«e;'^e5i5 " to designate the disruptive processes by which energy 

 is released, leaving respiration to designate the more superficial phenomena of 

 aeration. . . ." 



