In addition, it may be as well to remember that death sometimes occurs suddenly in exophthalmic goitre, hypertrophy of the thymus, and in Addison's disease. In some cases of sudden death nothing has been found post mortem, even when the autopsy has been made by skilled observers, and the brain and cord have been submitted to microscopical examination. VI.--SIGNS OF DEATH (1) Cadaveric appearance; ashy white colour. (2) Cessation of the circulation and respiration, no sound being heard by the stethoscope. Cessation of the circulation may be determined by (a) placing a ligature round the base of a finger (Magnus' test); (b) injecting a solution of fluorescin (Icard's test); (c) looking through the web of the fingers at a bright light (diaphanous test); (d) the dulling of a steel needle when thrust into the living body; (e) the clear outline of the dead heart when viewed in the fluorescent screen. (3) The state of the eye; the tension is at once lost; iris insensible to light, fundus yellow in colour; cornea dull and sunken. (4) The state of the skin; pale, livid, with loss of elasticity. (5) Extinction of muscular irritability. The above signs afford no means of determining how long life has been extinct. The following, however, do: =Cooling of the Body.=--The average internal temperature of the body is from 98 deg. to 100 deg. F. The time taken in cooling is from fifteen to twenty hours, but it may be modified by the kind of death, the age of the person, the presence or absence of clothing on the body, the surrounding temperature, and the stillness or otherwise of the air about the body. Still, the body, other things being equal, may be said to be _quite cold_ in about _twelve hours_.