716 BACTERIA IN AIR, SOIL, WATER, AND MILK 



goes on at temperatures varying from 50° C. to Q0° C, carbohydrates 

 are split up and much nicotin is destroyed.' The end products consist 

 largely of COj and various organic acids, butyric, formic, succinic, etc. 

 During the fermentation, bacteria of many varieties are found in the 

 heaps of tobacco leaves and many attempts have been made to deter- 

 mine flavors artificially by inoculating tobacco leaves of a poorer quality 

 with cultures obtained from the finer Havana grades. Suchsland^ and 

 others, who have attempted this, claim to have obtained marked im- 

 provements in domestic products by this method. The bacteria found 

 in tobacco fermentation belong to many varieties. Some of these are 

 closely related to the proteus and subtilis groups. Others are distinctly 

 thermophilic, an attribute required by the high temperatures attained 

 in the fermenting tobacco leaves. It is probable that the tobacco 

 flavors can not be regulated by bacteriological methods alone, since it 

 has been shown by Loew ^ that an important factor in the tobacco fer- 

 mentation is contributed by the leaf-enzymes, which, of course, depend 

 intimately upon soil and chmatic conditions. 



Opium Productions. — In the preparation of opium for smoking pur- 

 poses, the raw product is subjected to a prolonged period of fermentation 

 by which the carbohydrates in the material are destroyed. According 

 to various observers, the process is carried out in most cases by a species 

 of aspergfllus. 



Indigo Production. — Indigo, which is obtained from the plants 

 " Isatis tinctoria " and " Indigofer tinctoria," is not present, as such, in 

 the plants. In some of these it is found in the form of indican, in others, 

 as indoxyl. It has been shown by Alvarez and others that the oxida- 

 tion of indican and indoxyl into indigo-blue is carried out largely by 

 bacterial oxydases. Sterilized indigo plants do not produce the blue 

 color. Alvarez * has isolated a bacillus closely related to the Bacillus 

 mucosus capsulatus group, to the action of which he attributes this 

 oxidation. 



Bacteria in the Tanning of Hides. — Raw animal hides are subject 

 to decomposition until treated by a process known as tanning. This 

 consists first in the depilation of the dried and salted skins, either by 

 partial putrefaction in an atmosphere saturated with water vapor or 

 by chemical treatment with solutions of milk of lime. After this, the 



1 Behrens, quoted from Fltigge, "Die Mikroorganismen," Bd. 1, Leipzig, 1896. 



2 Suchsland, Ber. der Deut. botan. Ges., ix. 



3 Loew, Rep. U. S. Dep. Agriculture, 59, 1899. 



' Alvare:}, Comptes rend, de I'acad. de.s sci. vol. 105. 



