24 



The oxidations in tlie treatment of tobacco commence Avitli the curing 

 process and are continued in the fermenting process. In the latter 

 case, but not in the former, the aid of bacteria has been invoked for 

 explanation. But when oxidations can go on in the curing without 

 bacterial aid, even after the death of the cells, then it might be sup- 

 posed that the same cause would also lead to oxidation later on during 

 the fermenting i)rocess. Now, what is the true cause of these phe- 

 nomena"? There remains, in fact, as the only explanation the writer's 

 suggestion that an oxidizing enzijm is the final cause of the energetic 

 oxidizing action after death of the cells as it is capable of instigating 

 certain compounds to take up the molecular oxygen of the air. 



The formation of enzyms is a physiological necessity for every living 

 organism. Various enzyms come into action especially in the develop- 

 ment of shoots, as well as in the inanition state of the plants. Green 

 plants, as well as lower fungi, i)repare enzyms, which may act on 

 protein, polyanhydrids of glucoses, glucosides, or fat, splitting or dis- 

 solving these bodies and thus making them more easily accessible 

 to the i)rotoplasm.' The list of enzyms has been enlarged in recent 

 years by the oxidizing enzyms or the oxidases, which were brought to 

 our knowledge first by French savants, as Gabriel Bertrand, Bourque- 

 lot, Gouirand, Cazeneuve, and others. The most thorough investiga- 

 tions on this subject are those by Professor Bertrand, who has shown 

 their wide distribution through the vegetable kingdom.' 



The best reaction for -oxidizing enzyms consists in the production of 

 a blue color with the tincture of guaiac, which reaction can be obtained 

 with various vegetable objects. This blue coloration is produced in 

 many cases only upon addition of peroxide of hydrogen, in which case 

 it was formerly considered as a reaction upon diastase. While the crude 

 diastase of malt gives this blue reaction in a very marked degree, the 

 diastase of certain fungi {Aspergillus oryzcc) will, as the writer long 

 since ascertained, yield this reaction either only slightly or not at all, 

 although this diastase has very energetic qualities and produces glucose 

 from starch. Eaciborski and other authors also have proved that this 

 blue reaction is not characteristic of j)ure diastase, but only of an 

 admixture of an oxidase. 



The brown, black, or reddish coloration of freshly i^repared juices of 

 potatoes, turnips, etc., setting in when exposed to the air, the brown 

 color of the falling leaves in autumn, and similar phenomena are gen- 

 erally due to the action of the oxidases. The oxidation of tannin by 

 oxidases plays an important part in certain fruits ripening or overripe. 



'Atrophic irritatiou is exerted when rapidly developing cells or cells in a state 

 of iuauitiou require nourishment, and this stimulus leads to the production of 

 enzyms by the nuclei — an interesting case of physiological adaptation. Well- 

 nourished cells killed in the full vigor of life often give only slight indications of 

 amylolytic and i>roteolytic enzyms. 



2 Further contributions have been published by Griiss and by Eaciborski (Ber. d. 

 Dent. Bot. Ges., Vol. XVI, Nos. 3 and 5, 1898;. 



