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all physiological experience to suppose that the heart-action and respiration can be suspended entirely when once they are established, for a period as long. So, then, if no motion of the heart occurs during a period of five minutes—a period five times as great as observation warrants—death may be regarded as certain.

The respiratory movements of the chest are sometimes very difficult to observe. They can always be better appreciated if the abdomen and chest are observed together. There are two methods to determine whether respiration is absolutely suspended or not. First, by bolding a mirror in front of the open mouth, observing whether any moisture collects on its surface. Second, by placing on the chest a looking-glass or basin of water, and reflecting from it an image by artificial or sun light. The slightest movement would be registered by a change in position of the image. While the writer considers the absence of heart-beats and of respiratory movement an absolute test of death, still some cases may occur in which the establishment of this test is very difficult, and the following additional tests may be employed :

1. Temperature of the body same as surrounding air.

2. Intermittent shocks of electricity at different tensions passed into various muscles, giving no indication whatever of irritability.

3. Careful movements of the joints of the extremities and of the lower jaw, showing that rigor mortis is found in several parts.

4. A bright needle plunged into the body of the biceps muscle (Cloquet's needle test) and left there, showing on withdrawal no signs of oxidation.

5. The opening of a vein, showing that the blood has under. gone coagulation.

6. The subcutaneous injection of ammonia (Monte Verde's test), causing a dirty-brown stain indicative of dissolution.

7. A fillet applied to the veins of the arm (Richardson's test), causing no filling of the veins on the distal side of the fillet.

8. "Diaphanous test:" after death there is an absence of the translucence seen in living people when the hand is held before a strong light with the fingers extended and in contact.

9. “Eye test:" after death there is a loss of sensibility of the eye to light, loss of corneal transparency, and the pupil is not responsive to mydriatics.

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.
(6) 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 deathagony 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, ii 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 coag. ulating, 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 distin

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