In these conditions, however, all the activities of the body are reduced to the utmost, and respiration and circulation, so feeble as to be imperceptible to ordinary observation, suffice to keep the cells living.
With the cessation of life the body is subject to the unmodified action of its physical environment.

There is no further production of heat and the body takes the temperature of the surroundings.

The only exceptions are rare cases in which such active chemical changes take place in the dead body that heat is generated by chemical action.

At a varying interval after death, usually within twelve hours, there is a general contraction and hardening of the muscles due to chemical changes, probably of the nature of coagulation, in them.

This begins in the muscles of the head, extends to the extremities, and usually disappears in twenty-four hours.