In the living these injuries are accompanied with swelling, pain, and more or less discoloration of the part affected. Among malingerers it is not an uncommon practice to bruise the body to imitate the spots of purpura and scurvy. In scurvy, the condition of the gums common to that disease, and the state of the general health, will point to the true nature of the spots. The diagnosis of purpura will be assisted by noting the diffusion of the spots over the body. In old people purpuric spots frequently extend round the limbs, chiefly on one of the lower extremities. Many blood diseases are associated with ecchymoses and purpuric eruptions. Some persons are very easily bruised, and a pinch, by no means severe, will cause on their arms a severe bruise. Discoloration--ecchymosis--may take place in the skin, cellular tissue, muscles, or internal organs as a result of external injury, or it may be due to sudden and powerful contraction of a muscle or group of muscles. Not infrequently the discoloration does not appear over the seat of injury, but at some distance from it; and when the effusion is deep-seated, days may elapse before any discoloration of the skin takes place, and then it is not blue, as in superficial parts, but of a violet, greenish, or yellowish hue. A deep-seated ecchymosis may give no external sign of its presence; hence in all cases deep incisions should be made before an opinion is ventured as to the entire absence of this occurrence. This is very noticeable among the deep-seated muscles of a limb. In these cases, forty or fifty days may elapse before the deep-seated bruise shows its existence on the surface, and then only as irregular, yellowish, green, or bluish spots over the part. A very slight contusion, as a sprain of the ankle, may give rise to extended discoloration of the leg. An ecchymosis is not necessarily situated directly under the seat of injury. A blow given during life may not appear as an ecchymosis till _after death_. The change of colour in bruises begins at the circumference, and travels inwards. During the first three days the colour of the bruise is blue, bluish-black, or black; greenish on the fifth or sixth day; and yellow from the seventh to the twelfth. The extent of an ecchymosis depends greatly on the looseness of the cellular tissue. A slight contusion causes a slight redness and swelling, and may leave no mark on the dead body, unless death has taken place within thirty-six hours. Injuries of this kind sometimes leave a parchment-like hardness and discoloration of the skin. The part looks slightly depressed, due probably to the epidermis having been partly rubbed off, and the skin then drying. Similar marks are sometimes made by blisters. These marks may be produced on the dead body by friction and exposure to the air.