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same part that the hiemoglobiu does in animals, but neither is this 

 vievr justitied, as the oxidizing enzyms are not carriers of molecular 

 oxygen, but sim^^ly instigators of oxidation. 



The writers view on this subject is that as the living protoplasm can 

 oxidize carbohydrates and fat, but does not attack or attacks only with 

 difficulty compounds of the benzene group, and, on the other hand, as 

 just the opposite takes place with the oxidizing enzyms, it may be 

 inferred that there exists between the protoplasm and the oxidizing 

 enzyms a certain division of labor, the former oxidizing the compounds 

 of the methan series and the latter those of the benzene series. The 

 former provides for the kinetic energy of the cells: the latter destroys 

 by partial oxidation noxious by-products. The oxidations in the former 

 case are generally complete, but in the latter only partial. 



The oxidizing action of enzyms might be comi)ared to that of xdati- 

 num black. In both cases chemical energy is conveyed to certain 

 organic compounds, which are thus rendered capable of taking up the 

 oxygen directly from the air. The further inference might also be Jus- 

 tified that just as platinum black brings on not only oxidations, but 

 also reductions under certain circumstances, the same may be possible 

 for the oxidases; for example, if idatinum black is added to a mixture 

 of glucose and potassium nitrate in aqueous solution, a reduction of 

 nitrate to ammonia takes place by aid of hydrogen atoms in the sugar, 

 while the oxygen of the nitrate is thrown upon the glucose and organic 

 acids thereby formed. Wben the analogy of action of the oxidase to 

 platinum black is justified, there will be a simple explanation for the 

 disappearance of a certain portion of the nitrate and also of a certain 

 l)ortion of the glucose during the fermentation i)rocess of tobacco. Pre- 

 liminary qualitative experiments by the writer have indeed proved the 

 formation of ammonia under these conditions. A full account of quan- 

 titative tests will follow in a later bulletin. 



The oxidizing enzyms may occur in various parts of the plant — in 

 young and active as well as in dormant tissue. Grliss has observed that 

 there occurs frequently, but not always, a coijicidence between the trans- 

 formation of starch and increase of oxidase. Whether the amount of 

 oxidase augments with the ripening of fruits has not been thoroughly 

 investigated. Tolomei observed that in olives it does increase during 

 the ripening process. 



The juice of the fresh tobacco leaf soon turns dark upon exposure to 

 air and gradually forms a sediment, but if boiled this dark coloration 

 does not set in, the oxidase having been killed. 



Tlie tobacco oxidase and peroxidase. — There exist, evidently, two kinds 

 of oxidizing enzyms in the Florida tobacco leaf. The first kind oxidizes 

 guaiaconic acid (the characteristic reactive in the guaiac resin) to 

 guaiac blue without the aid of peroxide of hydrogen, but the second 

 kind oxidizes it only when this substance is present. Both kinds of 

 oxidizing enzyms, which may be distinguished as tobacco oxidase and 



