PRODUCTS OF VITAL ACTIVITY. 143 
bic microdrganisms are constantly 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 aérobic bacteria occurs later and is not attended 
with the same putrefactive odors, the products evolved being of a 
simpler chemical composition—CO,, HN, No doubt these aérobic 
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 anaérobics 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,, H,S, and H. 
Many of the bacteria of putrefaction are facultative anaérobics— 
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 anaérobic bacteria concerned in putrefaction have as yet 
received comparatively little attention. Among the aérobics and 
facultative anaérobics 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 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 microérganisms. 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 peptonizing 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. 
