58 THE STORY OF GERM LIFE. 



indigo is a product of bacterial fermentation, and 

 commonly due to a single definite species of bac- 

 terium. Of the details of the formation, however, 

 we as yet know little, and no practical applica- 

 tion of the facts have yet been made. 



BACTERIA IN TOBACCO CURING. 



A fermentative process of quite a different na- 

 ture, but of immense commercial value, is found 

 in the preparation of tobacco. The process by 

 which tobacco is prepared is a long and some- 

 what complicated one, consisting of a number of 

 different stages. The tobacco, after being first 

 dried in a careful manner, is subsequently allowed 

 to absorb moisture from the atmosphere, and is 

 then placed in large heaps to undergo a further 

 change. This process appears to be a fermenta- 

 tion, for the temperature of the mass rises rapidly, 

 and every indication of a fermentative action is 

 seen. The tobacco in these heaps is changed 

 occasionally, the heap being thrown down and 

 built up again in such a way that the portion 

 which was first at the bottom comes to the top, 

 and in this way all parts of the heap may be- 

 come equally affected by the process. After this 

 process the tobacco is sent to the different manu- 

 facturers, who finish the process of curing. The 

 further treatment it receives varies widely ac- 

 cording to the desired product, whether for smok- 

 ing or for snuff, etc. In all cases, however, 

 fermentations play a prominent part. Some- 

 times the leaves are directly inoculated with fer- 

 menting material. In the preparation of snuff 

 the details of the process are more complicated 

 than in the preparation of smoking tobacco. The 



