MICROBES, OR BACTERIA. 115 
found on the surface, which also absorb this gas and 
do not allow it to penetrate into the lower part of 
the liquid. 
This liquid now becomes the seat of two very 
distinct actions. In its interior, vibriones succeed to 
the free globules and zoogloea, of which they appear 
to be only a higher stage of transformation. These 
microbes multiply and change the albuminoid matter 
into more simple substances; insoluble cellulose, fatty 
bodies, and gaseous putrid matters. Meanwhile, the 
microbes on the surface actively consume the products 
thus developed, transforming them into carbonic acid, 
nitrogen, and the oxides of nitrogen, etc. This ex- 
plains why, when there is an insufficiency of oxygen, 
putrefaction may indeed begin; but it languishes, and 
is finally arrested. 
The cause of the fetid odours which escape from 
putrefying bodies and liquids is not well understood. 
It may be ascribed to the disengaged gases (carburetited, 
phosphoretted and sulphuretted hydrogen, and ammo- 
niacal compounds), and to the circulation of decom- 
posing organic particles. We also find formic, acetic, 
lactic, butyric, valerianic, and caproic acids, generally 
combined with ammonia, and the fatty acids which 
are one result of the successive disintegrations of 
albuminoid maiters. 
When these gases are disengaged, a substance 
remains which may be compared with humus, or 
vegetable earth. It is rich in fats, in earthy and 
