4. Post-mortem ecchymoses are very extensive, ante-mortem generally limited in area.
A peculiar appearance of cadaveric lividity is observed in bodies which have been wrapped in a sheet and allowed to cool or that have cooled in their clothing. It occurs in the form of bands or stripes over the whole surface, and often gives an appearance as of a person flogged. The explanation of this appearance is that the congestion of the vessels takes place in the interstices of the folds, while the parts compressed remain whole. The unbroken condition of the cuticle, together with the other characteristics just mentioned, are sufficient to distinguish these ecchymoses from those produced by violence. While cadaveric lividity is seen in all bodies after death, it is especially pronounced in those persons who have died suddenly in full health or by violence, as from apoplexy, hanging, drowning, or suffocation. It is very slight in the bodies of those who have died from hemorrhage or anæmia.
The time at which cadaveric lividity appears varies greatly. Casper, who has investigated the subject thoroughly, sets the time at from twelve to fifteen hours after death.
Putrefaction.
At a period varying from a few hours to three days after death, certain changes are seen in the human body which show that putrefaction has commenced. A change of color appears first upon the middle of the abdomen and gradually spreads over the rest of the body; it is first pale green, which gradually deepens, and finally becomes purplish or brown. This change in color is due to the action on the hæmoglobin of the gases developed by decomposition. Similar discoloration makes its appearance on the chest, between the ribs, on the face, the neck, the legs, and lastly on the arms, where it is more marked along the large venous trunks, and has sometimes been mistaken for marks of violence. The eyeballs become flaccid, and if exposed to the air the conjunctiva and cornea become dry and brown. Gases are formed, not only in the hollow organs of the abdomen but also in the skin. Those developed in the cavities of the head and face force frothy, reddish fluid or mucus from the mouth and nostrils, and may cause swelling of the features and protrusion of the eyes and tongue. It must be remembered that the gases while producing distention of the abdomen may also cause changes in the position of the blood and slight displacement of the organs; they may also force undigested food into the mouth and into the larynx, and so lead to suspicion of death from suffocation.
As putrefaction advances, after a period of five or six days the entire surface of the body becomes green or brown, the cuticle becomes loose and easily detached; the tissues flaccid and often bathed in a reddish serum in such situations as the neck, the groin, and the back part of the scalp. The thorax and abdomen become enormously distended, the features distorted and scarcely recognizable, and the hair and nails loosened. Beyond this, it is impossible to follow the changes leading to disintegration with any degree of certainty. The changes which I have just described as produced by putrefaction are the ordinary ones seen in a body exposed to the air at a moderate temperature, but it must be remembered that the time and rapidity of the development of these changes may be influenced by a large number of factors, and that they are of very little importance in estimating the time of death. I have seen bodies buried two months that have shown fewer of the changes produced by putrefaction than others dead but a week.
The appearance of a body buried in a coffin will be as follows after a period varying from a few months to one or two years. The soft tissues will have become dry and brown and the face and limbs covered with a soft white fungus. Hard white crystalline deposits of calcium phosphate will be found on the surface of the soft organs, and when found on the surface of the stomach care should be taken not to confound them with the effects of poison. In time the viscera become so mixed together that it is difficult to distinguish them. For the most part the changes that take place in a body buried in a coffin are similar, but much slower, to those that occur if the body is exposed to the air or buried in soil. Even under apparently identical circumstances the most varied results have been observed, so it is not possible for a medical jurist to fix a definite period of death or the time of burial from the appearance of an exhumed body. For example, Taylor records a case where after thirty-four years’ interment an entire and perfect skeleton was discovered, surrounded by traces of shroud and coffin, while in an adjoining grave all that remained of a body that had been dead twenty-five years were the long bones and base of the skull, In one case a body was found well preserved after six years’ burial and in another after even thirty years’ interment.
This brings us next to a consideration of those factors that favor or retard decomposition.