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126                                               MEDICAL  JURISPRUDENCE

body if the blood is still fluid, but they will remain permanent, and no more
will form, if the position is changed after the blood has coagulated.

It is Impossible to give the exact time at which the blood begins to
coagulate after death. About four hours after death is the usual period
when coagulation of the blood commences. Coagulation does not occur and
the blood usually remains fluid after death from asphyxia, and in cases where
a large quantity of saline infusion has been injected intravenously in the
treatment of acute haemorrhage. On the contrary, coagulation occurs readily
after death from acute infectious fevers, such as pneumonia,

The colour of post-mortem staining may, in certain cases, indicate the
cause of death. Thus, the colour is intensely bluish-violet and purple in
asphyxia, and is cherry red*or pink in poisoning by carbon monoxide or
hydrocyanic acid, and sometimes in burns or in cold and exposure. On the
contrary, the colour of post-mortem staining is chocolate or coffee-brown in
poisoning by potassium chlorate, potassium bichromate or aniline, and is
usually dark brown hi poisoning by phosphorus.

Rarely, hypostatic congestion resembling post-mortem lividity may be
seen a few hours before death in cases of cholera, plague, uraemia, morphine
poisoning, typhus, and asphyxia.

Post-mortem lividity or staining has sometimes been mistaken for bruises
caused by violence during life, and consequently innocent persons have been
prosecuted for murder, but acquitted afterwards, when the charge could not
be proved. Dead bodies were occasionally forwarded to me for post-mortem
examination with a report from the police that as a result of violence there
were bruises on the back, but, on inspection, the so-called bruises were found
to be nothing else but post-mortem staining.

The following are the points by which they can be differentiated : 

1.   Post-mortem staining occurs on an extensive area of the most depen-
dent parts of the body, and usually involves the superficial layers of the
true skin;  a bruise may occur anywhere on the body, usually takes the
shape of the weapon used, is limited in area, and generally affects the deeper

2.    Post-mortem staining does not appear elevated above the surface, but
has sharply defined edges ; a bruise appears raised above the level of the
surface, and its edges are not sharply defined.    There may sometimes be an
abrasion of the cuticle over a bruise.

3.    The colour, of post-mortem staining is uniform ; it may become green
when the body begins to putrefy ; whereas a bruise exhibits the usual changes
of colour, especially if it is a few days old.

4.   La the case of post-mortem staining there will be no abrasion of the
cuticle, but in the case of a bruise there may be an abrasion of the cuticle.

5.   Post-mortem staining, on being cut, does'not show any effusion of
coagulated or liquid blood into the subcutaneous tissues, but may show
minute drops of blood exuding from the divided ends of the distended capil-
laries and small veins ; a bruise, on the other hand, shows infiltration of the
tissues either with coagulated or liquid blood.

Along with the appearance of external post-mortem staining internal
hypostasis also takes place in the dependent portions of the visceral organs.
Thus, if a body has been lying on the back, post-mortem staining is frequently
found in the veins of the cerebral and spinal piamater, in the lateral and
occipital sinuses, in the posterior cerebral lobes, in the lower posterior sur-
faces of the lungs, in the posterior surfaces of the liver, spleen and kidneys,
and in the posterior parts of the stomach and intestines, especially those lying