CHAPTER XII 

 THE PLANT OXIDASES 



IN the last ten years the attention of physiologists has been 

 largely directed to the study of respiration and oxidations 

 which take place in living and dead cells. 



Numerous researches have been directed to the un- 

 ravelling of the complicated interrelations of the mechan- 

 ism whereby the fundamental need of oxygen is supplied, 

 and it has been shown that enzymes termed " oxidases " 

 are concerned in the utilization of this gas. 



It is with some of the more recent results of the study 

 of oxidases that this chapter is intended to deal. The 

 subject as it was known up to 1910 has been exhaustively 

 treated of by Kastle (1910), also by Czapek (1910) and Clark 

 (1910), to whose publications the author is much indebted.* 



SECTION I. THE NATURE OF PLANT OXIDASES. 



ENZYMIC NATURE OF OXIDASES. 



On the whole, the substances which effect oxidations in 

 plants have the properties of enzymes, though their be- 

 haviour is in some ways peculiar. The usual routine 



* I have followed the custom of the American authors, and of Fowler 

 (1911), Moore and Whitley (1909), in writing " oxidase " rather than 

 "oxydase," to denote the enzyme that splits up a (per)oxide. The 

 spelling " oxydase " has been taken directly from the French, in which 

 both " oxygen " and " oxydant " retain the letter " y." It seems an 

 undesirable anomaly to spell " peroxide " with " i " and " peroxydase " 

 with " y," as many do at present. 



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