When a body is in this condition it can hardly be determined whether a month or five months have elapsed since death occurred. After this all the soft parts change into a formless, pustulent mass. The cavities are open, the viscera are indistinguishable, and the bones are left bare. The rapidity with which these changes take place, varies under the influence of a great number of conditions. The bodies of infants usually decompose more rapidly than those of adults; fat bodies putrefy quicker than lean ones; the bodies of persons who die suddenly from violence, decompose less rapidly than the average, unless the body be considerably mangled. Exhausting diseases, fevers, and the puerperal condition, are followed by rapid decomposition, as is also death from suffocating gases. Poisoning by alcohol, by arsenic, and by sulphuric acid, may preserve the bodies for an unusual length of time. Atmospheric air, moisture, and warmth, quicken decomposition. At the same temperature, a body which has been for one week in the air, one which has been two weeks in the water, and one which has been eight weeks buried in the usual way, will all exhibit the same degree of decomposition. THE RIGOR MORTIS. It is proper to notice whether or not the body is in the condition of post mortem rigidity. More attention has, perhaps, been given to this post mortem condition than it well deserved. According to Kühne, the rigor mortis is produced by a change in the muscular fibres; the fibres first lose their contractibility, then there is coagulation of the myosine and loss of elasticity. When this acidity has reached its height, muscle becomes softer, and the rigor mortis gradually disappears; finally, the acid condition is succeeded by an alkaline fermentation, and decomposition ensues. The rigor mortis generally begins in the muscles of the lower jaw and back of the neck; it then extends to those of the face, neck, thorax, arms, and finally, the legs; it usually disappears in the same order; it generally begins in from eight to twenty hours after death, but often much sooner. The bodies of persons killed on the field of battle, and of those who have been drowned, sometimes seem to be overtaken by the rigor mortis at the very instant of death; the bodies retain the same position, and the face the same expression, which they had in the last moments of life. The rigor mortis may continue for from one to ten days, generally, but not always; death from narcotic poisons is followed by a short and feeble rigidity. While death by lightning is followed by rapid and intense rigidity, in young children, it is feeble and of short duration. The degree and duration of rigor mortis after death from violence, from different diseases, etc., is stated so variedly and contradictorily by different observers, that no definite rules can be given concerning it.