Enzymes are unorganized ferments and are cast off the living body within the living body. =Metabolic Fermentation.=—Metabolic fermentation is that process by which enzymes in the tissues of the living body destroy the dead cells, and reduce them to the following gases: nitrogen (N), carbon-dioxide (CO₂), ammonia (NH₃), uric acid, and other materials. In the living body these gases and other products are eliminated from the tissues, by the sudoriferous glands and ducts through perspiration, by the lungs with the expired air, by the intestines with the feces and by the kidneys with the urine. In the dead body the enzymes become active agents in tissue gas production, unless they are kept in restraint by being brought in contact with germicidal embalming fluids. =Putrefactive Fermentation.=—Putrefactive fermentation is the process by which undigested food substances (principally proteids), under the influence of ferment bacteria, yield gases. This change rarely takes place in the small intestines of the living body as the germs are held in restraint by lactic acid and acetic acid bacteria in those parts. There is little restraint to their activity in the large intestines, however, and the intestinal gases along with putrefactive changes in fecal material are a natural consequence. Intestinal fermentation is hastened in the dead body by the presence of much undigested food and the absence of any restraining organisms. The gases produced in the intestines of either the living or dead body by the action of putrefactive ferment bacteria are: carbon-dioxide (CO₂), hydrogen (H), nitrogen (N) hydrogen sulphide (H₂S), methane (CH₄). The continued fermentation in the stomach and the intestines causes a coffee colored material of a frothy character to purge from the mouth. When the hollow needle or trocar is used to reach the scene of ferment activity, the gases mentioned are released from the effected organs. As these gases are extremely odorous, they should be passed through a pledget of cotton saturated with formaldehyde, before being allowed to pass into the open air. Germicidal fluids when directed against the bacteria in an intelligent manner should destroy them and prevent their becoming active again. Putrefactive fermentation is divided as follows: abdominal fermentation, gastric fermentation, and intestinal fermentation.