THE CHEMISTRY OP BACTERIA. Ill 



The cut plants are placed in water and allowed to ferment, 

 whereby the glucpside is split up into its . constituents, 

 sugar and reduced or white indigo. The latter passes into 

 solution, and, on subsequent agitation with air, becomes 

 oxidized to the insoluble indigo-blue. 



Putrefaction. 



The decomposition of albuminous substances is a fer- 

 mentative change analogous in every respect to the changes 

 which carbohydrates and fats undergo. The cleavage of 

 dead organic matter is always brought about by the activity 

 of micro-organisms. A given organism may be capable of 

 splitting up carbohydrates, and thus, inducing a typical 

 fermentation when planted on a soil rich in these com- 

 pounds. The sam e germ, when grown on albuminous matter, 

 may produce a typical putrefaction. The difference be- 

 tween fermentation and putrefaction is, therefore, princi- 

 pally due to the different chemical composition of the 

 material that is acted upon. 



While the carbohydrates and fats contain merely 

 C, H and O, the protein substances contain, in addition, 

 N, S and at times P. Consequently, cleavage products 

 containing the latter elements will be met with in putrefac- 

 tion, which can not be present in ordinary fermentation. 

 These products may possess a more or less intensely disa- 

 greeable odor, and hence, putrefaction may be spoken of as 

 putrid fermentation. Among the compounds thus formed may- 

 be mentioned ammonia, and the amines, which possess a fish- 

 like odor; also, indol and skatol which are characteristic 

 products, of intestinal putrefaction and the cause of the 

 fecal odor. These substances contain the nitrogen which, 

 was present in the protein molecule. The sulphur of tlfe 

 protein molecule may appear as hydrogen sulphide, mer- 

 captans, etc. 



