THE METHOD OF MAKING POST-MORTEM EXAMINATIONS. 7 



may pass off very rapidly, ill rare cases in from one to three hours ; or 

 it may persist for two or three weeks or longer. It may be said in gen- 

 eral that the average time of its disappearance is within twenty-four or 

 forty-eight hours after its occurrence, depending on temperature, its 

 intensity, the mode of death, the period of its advent, etc. Caspar 

 states that in foetuses before term he has never observed rigidity, and 

 that in young children it is feeble and of short duration. Its occurrence 

 and phenomena may be in some cases of the highest medico-legal impor- 

 tance ; but its careful observation does not, with our present knowledge 

 of its significance, appear essentially to further the aims of the practical 

 pathologist. ' 



Contusions. It is often important to determine whether violence has 

 been inflicted upon a body before death. In regard to this point, we 

 must remember, first, that blows and falls of sufficient violence to frac- 

 ture bones and rupture the viscera may leave no marks on the skin, even 

 though the person has survived for several days ; and, second, that there 

 are post-mortem appearances which simulate ante -mortem bruises. A 

 severe contusion during life may present, at first, no mark or only a 

 general redness. After a short time the injured part becomes swollen 

 and of a red color ; this color may be succeeded by a dark blue, and this 

 in turn fade into a greenish yellow or yellow ; these later appearances 

 are due to an escape of blood from the vessels and to a subsequent de- 

 composition of haemoglobin. If therefore we cut into such an ecchy- 

 mosis after death, we find extravasated blood or the coloring matter of 

 the blood, in the form of pigment granules, free in the tissues. Post- 

 mortem, discolorations, on the other hand, although their external ap- 

 pearance may resemble that of ante-mortem ecchyniosis, are not formed 

 by an extravasation of blood, but by a circumscribed congestion of the 

 vessels or by an escape of blood-stained serum. If we cut into such dis- 

 colorations, therefore, we find no blood outside the vessels. Care should 

 be taken not to mistake the lesions of ha?morrhagic infection for trau- 

 matic ecchymoses. 



Blows on the skin of a body which has been dead for not more than 

 about two hours may produce true ecchymoses with extravasation of 

 blood, such as can be distinguished with great difficulty or not at all 

 from those formed during life. If putrefactive changes be present, the 

 difficulty of distinguishing between aute-morteni and post-mortem bruises 

 is greatly enhanced. 



Hanging and strangulation are attended with the formation of marks 

 on the neck which are described in works on forensic medicine. These 

 marks must not be confounded with the natural creases of the skin of 

 the neck. Many adults during life have creases of the skin of the neck ; 

 one or more in number, running downward from the ear under the chin 

 or encircling the neck. After death these creases may be much more 



1 For further details concerning rigor mortis, putrefactive changes, particularly the 

 later stages, and the phenomena of cooling of the body, see Tidy, "Legal Medicine," 

 vol. i., or other works on medical jurisprudence. 



