which represents the formation of lactic acid.
In addition, formic and butyric acids are produced along with small quantities of other bodies, as will be shown. It is pretty certain that the butyric acid is formed by the further fermentation of the lactic acid and lactic salts in the liquid; at the same time CO2 and hydrogen are evolved as follows:—
2 C3H6O3 = C4H8O2 + 2 CO2 + H2
Fig. 27.—Organisms in Bran Drench × 1000.
Fig. 28.—Chains of Bran Bacteria × 1000.
Fig. 27 is a drawing of the organisms seen in the drench, under a magnification of 1000 diameters. This was taken from a drench which had been set about 3 hours, and was just beginning to ferment; the bacteria form chains of varying length: the short chains have a slow motion in the liquor. As the fermentation proceeds, these form longer chains (Fig. 28), some of which are very beautiful objects, especially when viewed by dark ground illumination. The other organisms present are bacteria and bacilli from the puer, and at a later stage, as the nutrient material for the bran ferment becomes less, they begin to develop, first causing butyric and finally putrefactive fermentation.