3. Air.—If access of air to a body be prevented in any way by its inclosure in a coffin, by closely fitting clothes, or by complete immersion in water, putrefaction is retarded.
4. Age.—Adults and old people decompose more slowly than children. Males are said to change less rapidly than females, lean people than fleshy ones.
5. Cause of Death.—Putrefaction is delayed after death from chronic diseases unless they are associated with dropsy. Poisoning by alcohol, chloroform, strychnine, and arsenic retard putrefaction. In the latter case the putrefactive changes seem to stop after they have once commenced, and often a result very similar to mummification is seen. Death from the mineral acids, especially sulphuric, appears to delay putrefaction.
6. Manner of Burial.—Putrefaction is retarded by burial a short time after death; by interment on high ground, in dry, sandy, or gravelly soil; by having the grave deep, over six feet in depth if possible by the body being well wrapped and secured in a tight coffin, a lead one being the best in this respect. Lime or charcoal applied freely about a body will retard decomposition, as will also injection of the body through the arteries with such substances as arsenic, chloride of zinc, or antimony. The ultimate effect of putrefaction is to reduce all bodies to inorganic compounds, chiefly water, ammonia, and carbon dioxide. Three conditions are necessary for its establishment, (1) a given temperature, (2) moisture, (3) free access of air.
The order in which the various organs and tissues undergo decomposition, as given by Casper, who has investigated the subject carefully, is as follows: Trachea and larynx, brain of infants, stomach and intestines, spleen, omentum and mesentery, liver, brain of adults, heart and lungs, kidney, bladder and œsophagus, pancreas, large vessels, and last of all the uterus.
As the result of putrefaction, fluids, generally blood-stained, collect in the serous cavities of the body, and should not be confounded with serous effusions occurring during life. So also the softening of the organs and tissue resulting from decomposition should be carefully distinguished from those resulting from inflammation. These cadaveric softenings are most frequently found in the brain, spleen, and gastro-intestinal mucous membrane. Inflammatory softenings are differentiated by being rarely general but almost always limited, by the substance of the inflamed part being infiltrated with serum or pus and showing traces of vascular injection. In doubtful cases the pathologist should have recourse to the microscope.
As the result of putrefaction, various changes take place in the mucous membrane of the stomach and intestines which simulate the effects of poisons. The color of the stomach varies from red, which becomes brighter on exposure to the air, to a brown, slate, or livid purple. We can only presume that these color-changes are the result of irritant poisons when they are found in non-dependent parts and parts not in contact with organs engorged with blood, when they are seen soon after death, and when the membrane is covered with coagulated blood, mucus, or flakes of membrane.
Effects on Putrefaction of Submersion in Water.
There are certain modifications of the putrefactive changes when bodies have been submerged in water. In the first place, the changes are much less rapid; they often do not show themselves until about the twelfth day, and then as discolorations appearing generally first about the ears and temples, then on the face, from which they spread to the neck, shoulders, chest, abdomen, and finally to the legs. This is almost the inverse order of the putrefactive changes in bodies exposed to the air. As a result of the formation of gases, the body in a short time becomes buoyant; after floating on the surface of the water for a time, the gases escape and the body sinks, rising a second time when fresh gas has formed.