FERMENTATION BY BACTERIA. 601 



quantities of sulphuretted hydrogen, aldehyde, isobutyric 

 acid, acetic acid. The second fermentation occurs when Second kind. 

 an alkaline extract of meat solution is employed; in that 

 case only carbonic acid and hydrogen are formed, along 

 with the same bye-products as in the former fermenta- 

 tion. Tappeiner* has ventured to conclude from his 

 researches that the solution and decomposition of cellu- 

 lose in the intestine of ruminants only occurs as the 

 result of this fermentation, and that therefore the cellu- 

 lose is of no nutrient value for the organism. According 

 to the experiments and calculations of Wilsingt and 

 Henneberg and Stohmann, J however, this view does not 

 seem to be accurate, and only a part of the cellulose 

 which disappears in the intestine is lost by fermenta- 

 tion. 



Other Fermentations. 



In the case of various carbo-hydrates, Fitz observed a fer- Various other 

 mentation in which sethylic alcohol was formed as the chief fermentations, 

 product. From 500 grammes of starch he obtained 10 grammes 

 of aethylic alcohol; from the same quantity of dextrine 22 

 grammes ; milk-sugar also furnished chiefly the same alcohol. 



Bontroux found a transformation of milk sugar into gluconic 

 acid by a species of bacterium similar to themycoderma aceti. 



To Brieger we owe the knowledge of a number of fermenta- Fermenta- 

 tions of carbo-hvdrates caused bv pathogenic bacteria. Ac- tin s by . 



, . J , . 1 ., ,., ..pathogenic 



cording to this author bacillus cavicida splits up solutions or organisms. 



grape-sugar in such a way that propionic acid is the chief 

 product. Bacillus pneumonias causes a marked development 

 of gas in five per cent, sugar solutions to which a little 

 nutrient gelatine has been added, and in the fluid there is 

 acetic acid as the chief product of the fermentation, and, in 

 addition, small quantities of formic acid and aethylic alcohol. 

 Typhoid bacilli formed from grape sugar or starch aethylic 

 alcohol, acetic acid, and lactic acid. A non -pathogenic 

 coccus, obtained from faeces, which forms on gelatine flat 

 pyramids of a glistening white colour, decomposes three per 

 cent, grape-sugar or cane-sugar solution in such a way that 

 asthylic alcohol along with traces of acetic acid is formed. 



* Tappeiner, Chem. Ber.. vol. IQ.Zeilschr.f. BioL, vol. 20. 



f Wilsing, ibid. Henneberg nnd Stohmann, ibid., vol. 21. 



