132

Scientific Memoirs by

which serve to render this soluble and so available for the supply of food and
energy to the cells. Thus sugars are "inverted" and albumen peptonized
by the enzymes, and these soluble products are thus laid open to attack by
the cells. Nitrogenous bodies then are split up by putrefaction into a large
number of simpler compounds, some of which are non-nitrogenous; first
we get albumoses and peptones, due to the action of enzymes just as in the
case of digestion (pepsin), and these later undergo a further splitting up into
certain aromatic compounds and amido-bodies; further, fatty and aromatic
acids (non-nitrogenous) are produced, and finally we get the inorganic end pro-
ducts, such as free nitrogen and hydrogen, ammonia, carbonic acid, methane
and sulphuretted hydrogen. All the former complex bodies are broken down
to these last, the original substratum being radically transformed—

      (1) by assimilation of food material by the living fungi;

      (2) by the secretory products elaborated by these (enzymes);

      (3) by the special protoplasmic activity of the living cells.

   As a result, we recognise that so far there has been no formation of oxidized
products, that there has been no oxidation,—though there has been a constant
wandering of the "fixed" oxygen atom—and we find a parallel to the processes
of digestion, in which both nitrogenous and non-nitrogenous foods are altered and
rendered soluble before the products can enter the blood stream and be oxidized.
So far, then, we have been dealing with the action of bacteria deprived of free
oxygen (an anaërobiosis), to the significance of which we have already drawn
attention.

   Side by side with this resolution of the nitrogenous waste, we find also that
the waste carbohydrates, both of the original refuse and those formed in the
breaking down of nitrogenous matters, e.g ., the organic acids and fats, are similar-
ly broken down into simpler compounds by a series of specific fermentations,
due also to the vital activity of living bacterial cells and to the enzymes they
secrete. Carbon dioxide, free hydrogen, methane, and other gases of reduction
are the characteristic end-products of carbohydrate dissolution, and as in the
former case we arrived at the final terms of the nitrogen series, we here obtain
the final term of the carbon series by processes of reduction, hydrogen being
set free in both cases.

   We have now arrived at the point where we have a series of end-products
of putrefaction and fermentation, notably ammonia, free nitrogen, marsh gas,
carbonic oxide and free hydrogen, together with certain organic acids, and some
intermediate products which vary in kind and quantity according to the activity
and length of this first stage, the whole series of changes being gradual and of a