140 PRODUCTS OF VITAL ACTIVITY. 



doubt, arc, .nling to whether they are or are not supplied with atmos- 

 pheric oxygen. 



The anaerobic bacteria concerned in putrefaction have as yet 

 received comparatively little attention. Among the aerobics and 

 facultative anaerobics the following are best known: Micrococcus 

 foetidus, Bacillus saprogenes I., II., and III., Bacillus coprogenes- 

 foetidus, Bacillus putrificus coli, Proteus vulgaris, Proteus Zenkeri, 

 Proteus mirabilis, Bacillus pyogeues foetidus, Bacillus fluorescens 

 liquefaciens, Bacillus pyocyaneus, Bacillus coli communis, Bacillus 

 janthinus. 



Sithihh' /-V/ -im-iifti. Several species of bacteria produce soluble 

 ferments capable of changing starch into maltose, dextrin, etc. 

 Hueppe has shown that the lactic-acid bacillus produces a diastase, 

 and Miller obtained 1'nnn the human intestine a species which dis- 

 -olves starch. Marcano, by filtering cultures of species capable of 

 this ferment action through porcelain. \vas able to show that the 

 effect is due to a soluble ferment, which must have been produced 

 by the vital activity of the living microorganisms. Wortmann also 

 obtained a diastase from culture liquids which was precipitated by 

 alcohol ;ind again dissolved in water: in slightly acid solutions it 

 promptly converted starch into glucose. This is said to be produced 

 in culture liquids only when these do not contain albumin. In the 

 presence of all mini n a peptonizing ferment was formed; in its ab- 



e. a diastase by which starch was dissolved to serve as pabulum 

 for the bacteria present. These experiments were not made with 

 pure cultures, and more exact researches in this direction are de- 

 niable. 



A peptonizing ferment for gelatin is produced by a considerable 

 number of bacteria, as stated under the heading "Liquefaction of 

 Gelatin." The jellified albumin in cultures in blood serum is also 

 liquefied by a peptoni/in- ferment prod need by certain species of ba.-- 



>' authors also speak of a soluble ferment capable of inverting 



cane sugar or milk >n-ar. According to Hueppe. such a ferment 



iced by the Bacillus acidi lactici. A soluble ferment for cel- 



hlkMH is Mippo^-d by Flttgge to be produced by several species 



mOOg Others by Bacillus butyricus and by Vibrio ruguhi. 



Sev.-ral bacilli produce a soluble ferm.'iit capable of coa-'ulatiiiLC 

 tin- 'MMin of milk. 



l: "" </ \ftrates, <! \i'tnn<;,fi<>n.The researches of 



Gayon. hupettit. and others show that certain bacteria are able to 

 reduce nitrates with liberation qf ammonia and free nitrogen. This 

 is effected in the absence of oxygen by anaerobic bacteria, and. 



