POST-MORTEM CHANGES.
The human body after death undergoes certain changes which will be discussed under the following heads:
1. Cooling of the body.
2. Flaccidity of the body.
3. Rigor mortis.
4. Changes in color due to
(a) Cadaveric ecchymoses.
(b) Putrefaction.
Cooling of the Body.
Immediately after death there is a slight rise of temperature, supposed to be due to the fact that the metabolic changes in the tissues still continue, while the blood is no longer cooled by passing through the peripheral capillaries and lungs.
The body gradually cools and reaches the temperature of the surrounding air in from fifteen to twenty hours; this is the ordinary course, but the time may be influenced by a variety of causes, such as the condition of the body at the time of death, manner of death, and circumstances under which the body has been placed.
In certain diseases, as yellow fever, rheumatism, chorea, and tetanus, the temperature of the body has been known to rise as high as 104° F. and remain so for a time. Again, it has been observed that when death has taken place suddenly, as from accident, apoplexy, or acute disease, the body retains its heat for a long time. The bodies of persons dying from hanging, electrocution, suffocation, or poisoning by carbon dioxide, do not generally cool for from twenty-four to forty-eight hours, and cases are recorded where three days have elapsed before the body was completely cold. On the other hand, bodies dead from chronic wasting diseases or severe hemorrhage cool very rapidly, even in four or five hours.
In determining the temperature of a dead body the hand is not a reliable guide: the thermometer should always be used.
Flaccidity.
The first effect of death from any cause is general relaxation of the entire muscular system. The lower jaw drops, the eyelids lose their tension, the limbs are flabby and soft, and the joints become flexible.
In from five to six hours after death, and generally while the body is in the act of cooling, the muscles of the limbs are observed to become hard and contracted, the joints stiff, and the body unyielding. Muscles which are contracted in the death-agony do not necessarily become relaxed at any time.
The muscular tissues in the dead body can be considered as passing through three stages: (1) flaccid but contractile, (2) rigid and incapable of contraction, (3) relaxed and incapable of further contractility.
Rigor Mortis.
This is sometimes called cadaveric rigidity and occurs generally within six hours after death and disappears within sixteen to twenty-four hours. Many theories have been advanced to account for it, but the most probable one is that the rigidity is due to the coagulation of the myosin in the muscles by the weak acids which are no longer removed from the system; the muscles always give an acid reaction and are opaque instead of transparent; after putrefaction has set in ammonia is developed, the myosin dissolved, and so flaccidity results.
Rigor mortis occurs first in the muscles of the eyelid, next the muscles of the lower jaw and neck are affected, then the chest and upper extremities; afterward it gradually progresses from above downward, affecting the muscles of the abdomen and lower limbs. The rigidity disappears in the same sequence. The period after death when rigor mortis manifests itself, together with its duration, is chiefly dependent upon the previous degree of muscular exhaustion. Brown-Séquard has demonstrated that the greater the degree of muscular irritability at the time of death, the later the cadaveric rigidity sets in and the longer it lasts. He has also shown that the later putrefaction sets in, the more slowly it progresses.
The more robust the individual and the shorter the disease, the more marked and persistent is this muscular rigidity. It has been noticed that the bodies of soldiers killed in the beginning of an engagement become rigid slowly, and those killed late quickly. This explains the reason why bodies are sometimes found on the battle-field in a kneeling or sitting posture with weapons in hand.
If the rigidity of rigor mortis after it is once complete is overcome, as in bending an arm, it never returns; but if incomplete it may return. This will serve at times to distinguish real death from catalepsy and its allied conditions. While the average duration of rigor mortis has been given as sixteen to twenty-four hours, it must be remembered that in some cases it has been known to last only a few hours, as in death by lightning or by electrocution. In other cases it has persisted for seven and fourteen days.
This long continuance of rigor mortis has been noted in death from strychnine and other spinal poisons, in suffocation, and in poisoning by veratrum viride.
Atmospheric conditions modify to a large extent the duration of rigor mortis. Dry, cold air causes it to last for a long time, while warm, moist air shortens its duration. Also immersion in cold water brings on rigor mortis quickly and lengthens its duration.
Cadaveric Ecchymosis—Cadaveric Lividity or Hypostasis.
Within a few hours after death the skin of the body, which is of a pale, ashy-gray color, becomes covered by extensive patches of a bluish or purple color, which are most pronounced and are first seen on the back part of the trunk, head extremities, ears, face, and neck, and are due to the blood, before coagulating, settling in the most dependent parts of the body, producing a mottling of the surface with irregular livid patches. There is also a stagnation of blood in the capillary vessels, especially in those in the upper layer of the true skin or in the space between the cuticle and cutis. The discoloration continues to increase until the body is cold, when it is entirely arrested. Later on, just before putrefaction begins, the color deepens, and the change appears to proceed from an infiltration of blood pigment into the dependent parts of the body.
At the same time the discolorations are appearing on the surface of the body, internal hypostasis is also taking place, most marked in the dependent portions of the brain, lungs, intestines, kidneys, and spinal cord.
This condition in the brain may be mistaken for so-called congestive apoplexy; in the lungs, for pulmonary apoplexy or the first stage of lobar pneumonia; in the intestines and spinal meninges, for the beginning of inflammatory changes.
The position of these hypostases will afford the best correction for this possible error. The appearances presented by cadaveric ecchymoses have often been mistaken for the effects of violence applied during life. Innocent persons have been accused and tried for murder or manslaughter on charges afterward proved to be groundless. Therefore it is of the utmost importance that the medical jurist should be able to distinguish between ante-mortem and post-mortem ecchymoses.
The following are the points of difference:
1. Situation. Post-mortem ecchymoses are seen on that portion of the body which has been most dependent, generally the posterior aspect, and they involve principally the superficial layers of the true skin; ante-mortem ecchymoses may occur anywhere, and generally the deeper tissues are discolored.
2. In cadaveric lividity there is no elevation of the skin and the discoloration terminates abruptly.
3. After cutting into the tissues where an ecchymosis has been produced by violence, the blood without the vessels is free in the tissue; this is not so in cadaveric ecchymosis.
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.
Circumstances Favoring Putrefaction.
1. Temperature.—Putrefaction advances most rapidly at a temperature between 70° and 100° F. It may commence at any temperature above 50° F., but it is wholly arrested at 32° F. So one day’s exposure of a body in summer may effect greater changes than one week in winter. After freezing, putrefaction takes place with unusual rapidity upon the thawing out of the body. A temperature of 212° F. stops all putrefactive changes.
2. Moisture.—Putrefaction takes place only in the presence of moisture. An excess of moisture, however, seems to retard the process, possibly by cutting off the excess of air. The viscera according to the amount of water they contain decompose at different times after death—for instance, the brain and eye rapidly, the bones and hair slowly.
3. Air.—Exposure to air favors decomposition by carrying to the body the micro-organisms which bring about putrefaction; absence of air soon arrests the changes: this is seen in bodies hermetically sealed in lead coffins, which remain unchanged for a long period of time. Moist rather than dry air favors putrefaction by lessening evaporation. Air in motion retards while still air favors the change.
It is to be remembered that a body decomposes more rapidly in air than in water or after burial. Given similar temperatures, the amount of putrefaction observed in a body dead one week and exposed to the air will about correspond to one submerged in water for two weeks or buried in a deep grave for eight weeks.
4. Age.—The bodies of children decompose much more rapidly than those of adults; fœtuses still more rapidly. Aged bodies decompose slowly, probably on account of a deficiency of moisture. Fat and flabby bodies decompose quickly for the same reason.
5. Cause of Death.—In cases of sudden death, as from accident or violence, the body decomposes more rapidly than when death results from disease. Putrefaction sets in early in death from the infectious fevers, such as typhus, pyæmia, and typhoid fever, also in death from suffocation by smoke or coal gas, by strangulation or after narcotic poisoning. Those parts of a body which are the seat of bruises, wounds, or fractures, decompose rapidly; this is especially seen in parts after a surgical operation.
6. Manner of Burial.—When a body is buried in low ground in a damp, swampy, clay soil, decomposition advances rapidly, as also when the grave is shallow so the body can be exposed to constant variations of temperature. A porous soil impregnated with animal and vegetable matter favors putrefaction, as also burying a body without clothes or coffin; this is especially seen where infants have been thrown into the ground and loosely covered with earth.
Circumstances Retarding Putrefaction.
1. The Temperature.—Below 32° F. and above 212° F. putrefaction is entirely arrested. The rapidity of the change considerably lessens as the temperature advances above 100° F. A remarkable instance of the preservative power of cold is given by Adolph Erman, who states that the body of Prince Menschikoff, a favorite of Peter the Great, exhumed after ninety-two years’ burial in frozen soil, had undergone hardly any change. Buried in hot sand as is seen in the desert, a body putrefies very slowly and generally becomes mummified.
2. Moisture.—Absence of moisture retards decomposition. In the dry air of the desert bodies have been preserved for a long period of time.
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.
The rapidity of decomposition in water varies, being most rapid when the temperature is from 64° to 68° F. Stagnant as well as shallow water favors putrefaction. If a body becomes coated with mud the change is delayed. Submersion in a cesspool also retards it, and the conditions are such as to favor the formation of adipocere.
After a body has been removed from the water an exposure of a very few hours to the air causes rapid decomposition, so that in twenty-four hours more marked changes may occur than would have resulted from a fortnight’s longer submersion. The face soon becomes bloated and black, so that identification is well-nigh impossible. It is quite important in medico-legal cases to estimate the time which has elapsed since death in bodies found submersed in water. The following are the various changes ordinarily seen at different periods of time, as estimated by Devergie, who has especially investigated the subject:
First Four or Five Days.—Little change: rigor mortis may persist, particularly if the water is cold.
Fourth or Fifth Day.—Skin of the ball of the thumb and little finger, also the lateral surface of the fingers, begins to whiten. This whitening gradually extends to the palms of the hands and soles of the feet. The skin of the face will appear softened and of a more faded white than the rest of the body.
Fifteenth Day.—Face slightly swollen and red; a greenish spot begins to form on the neck and skin of the mid-sternum. The skin of the hands and feet is quite white and wrinkled. The subcutaneous cellular tissue of the thorax is reddish and the upper part of the cortical substance of the brain of a greenish tint.
At One Month.—The face is reddish-brown, the eyelids and lips green and swollen, and the neck slightly green. A greenish discoloration is also seen over the upper and middle part of the sternum. The skin is wrinkled. The hair and nails still remain intact. The scrotum and penis are distended by gas. The lungs become very emphysematous and overlap the heart.
Saponification.
When the bodies were removed from the Cimetière des Innocents in Paris, in 1786, Fourcray observed that many of them had been converted into a substance which he termed ADIPOCERE. He gave it this name because it resembles both fat (adeps) and wax (cera). Under certain circumstances which will be considered later, it is known to be a late product of the putrefactive processes. Adipocere is a substance of a cheese-like consistency, yellow or yellowish-brown in color, and composed chiefly of a mixture of the fatty acids. Chevreul has shown by analysis that it is a true ammoniacal soap, but that when formed in water impregnated with lime a calcareous may be substituted for an ammoniacal base. This may take place either in a body exposed to river-water or buried in a grave wet by water containing calcium carbonate or sulphate. Saponification can only take place when animal fat is in contact with nitrogenous matter. Neither fat nor fibrin when kept separate will saponify. Skin deprived of all its fat will not be transformed into adipocere.
Saponification commences in the fat of the female breast, of the cheeks and other parts of the body where large accumulations of fat are found, such as around the kidneys and in the omentum. As fat is distributed extensively throughout the body, nearly all parts may undergo this transformation. Taylor gives the following conditions as favorable to the change:
1. Bodies of young persons, because the fat is abundant and chiefly external.
2. Bodies of corpulent adults.
3. Exposure of bodies to the soil of water-closets.
4. The immersion of bodies in water, the change taking place more rapidly in running than in stagnant water.
5. Humid soil, especially when bodies are placed in it one upon the other. In this case the lowest of them is first changed.
When a body has been completely saponified it may remain in this state for years. In one instance, after seventeen years’ burial many of the organs could still be recognized.
The time required for saponification to take place is sometimes of medico-legal importance. Three years are usually necessary for bodies buried in the earth. The change occurs more rapidly in water. Cases are recorded where the body of a new-born child was completely saponified in six weeks, and again, the change had commenced in a body which had been in the water about four months; but these are unusual cases.