294 AGRICULTURAL BACTERIOLOGY. 



tion. Fermentation due to bacteria may certainly produce a 

 rise in temperature, but a rise as high as 130 F. is entirely 

 beyond anything that could be expected of living microorgan- 

 isms. Not all bacteria can endure such a temperature, and 

 there is no reason for thinking that they can produce the rapid 

 rise that occurs in the fermenting tobacco. Secondly, while 

 it is true that bacteria may be found upon the leaves of the 

 fermenting tobacco, Loew found them only in small quantities, 

 far too few to account for the fermentation which was produc- 

 ing a rise of temperature of 10 degrees per day. Further, 

 the amount of moisture in the tobacco leaves is low, not over 

 25 per cent., and in such a condition bacteria do not readily 

 grow ; indeed Loew believed that they could not grow at all. 

 Lastly, nicotine is generally looked upon as a means of check- 

 ing bacteria, and hence the fermenting tobacco cannot be 

 regarded as a favorable place for bacteria to grow. For all 

 these reasons Loew concluded that bacteria are not the active 

 agents in tobacco fermentation. 



But Loew obtained positive as well as negative results. He 

 found by proper study that the tobacco leaves contain certain 

 chemical substances which are capable of exerting a strong 

 oxidizing action, and hence of giving rise to the chief phenom- 

 ena of tobacco fermentation without the aid of bacteria. These 

 bodies he called oxydasc and pcroxydase, both of which he 

 found in abundance on the leaves. They were regarded by 

 him as enzymes and he believed them capable of producing all 

 of the phenomena of fermentation. Loew's careful studies 

 have subsequently been confirmed by some of the students 

 who had been working upon the bacteriological side of the 

 problem, and may therefore be taken as abundantly demon- 

 strated. It may be taken as demonstrated that there arc de- 

 veloped in the tobacco leaves certain chemical substances which 

 carry on an active, oxidizing function, and that it is these bod- 

 ies which arc chiefly concerned in the prominent phenomena 



