PRODUCTS OF VITAL ACTIVITY. 143 



bic microorganisms are constantl} 7 present in the intestine, and after 

 death they quickly invade the body and multiply at its expense 

 under favorable conditions as to temperature. The surface decom- 

 position due to aerobic bacteria occurs later and is not attended 

 with the same putrefactive odors, the products evolved being of a 

 simpler chemical composition CO 2 , HN 3 . No doubt these aerobic 

 bacteria, by consuming the oxygen and forming an atmosphere of 

 carbon dioxide, help to make the conditions favorable for the con- 

 tinued development of the anaerobics in the interior of the organic 

 mass ; at the same time they find a suitable pabulum in some of the 

 more complex products of decomposition occurring in the absence 

 of oxygen. The gases produced in the interior of a putrefying mass 

 are mainly CH 4 , H 2 S, and H. 



Many of the bacteria of putrefaction are facultative anaerobics 

 that is to say, they are able to multiply either in the presence of oxy- 

 gen or in its absence. The products evolved by these differ, no 

 doubt, according 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 

 fcetidus, Bacillus saprogenes I., II., and III., Bacillus coprogenes 

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

 Proteus mirabilis, Bacillus pyogenes fcetidus, Bacillus fluorescens 

 liquefaciens, Bacillus pyocyaneus, Bacillus coli communis, Bacillus 

 janthinus. 



Soluble Ferments. 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 from the human intestine a species which dis- 

 solves starch. Marcano, by filtering cultures of species capable of 

 this ferment action through porcelain, was 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 and 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 albumin a peptoiiizing ferment was formed ; in its ab- 

 sence, 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- 

 sirable. 



