The aperture of entrance and exit must, if possible, be determined. On this point there is much difference of opinion. The wound of _exit_ is always _smaller_ than the wound of _entrance_ (Casper). In this opinion Casper agrees with M. Malle, Olliver d‘Angers, and M. Huguier, but is opposed by Taylor, M. Matthysens, and others. “The characters of a gunshot wound,” says Assistant-Surgeon Neill, “are those of a contusion and laceration of all the tissues. Sometimes they are so simple as to bear resemblance to a punctured wound, particularly if a rifle-ball (conoidal), revolving on its long axis, has passed through the soft parts at a great speed, but within a few hours it resembles a contusion. The wound of entrance, as it has been termed, bears no comparison in size or shape to that of the exit when a rifle-ball has caused the injury. In the former you see the edges of the wound curving inwards, and the circumference small, with little or no hæmorrhage. In the latter, the wound is large, with torn and irregular edges projecting outwards, and perhaps only slight oozing of blood. In a short time, averaging an hour, round the entrance wound slight redness begins, gradually extending to about two inches round its orifice. Again, this colour changes to a blue- or greenish-black, and you see all the appearances of a severe bruise, with a small wound of the skin, its edges still curved inwards. In the exit wound the discoloration of the skin is not apparent.” The probable reason for the discrepancies in the statements of observers, as to the characters of entrance and exit wounds, may be found in the fact that experiments have been conducted with different-sized balls, different kinds of weapons, with varying quantities and qualities of the powder used, the character of the wads, and with varying velocities and distances. As pointed out by M. Roux, the two openings may be equal if the ball preserves the same velocity through the tissues as it possessed before entrance; the _entrance_ hole is smaller than the _exit_, when the ball has lost much of its trajectile force, and enters the softer parts of the body first; the _entrance_ is larger than the _exit_, when the ball first enters through the denser tissues of the body, and leaves through the softer. The opening of entrance made by the ball has generally, but by no means always, inverted edges. The edges of the exit opening are everted, bloody, and raw; but both the entrance and exit wounds may be everted in fat persons, due to the protrusion of the fat; and this eversion may also result from the expansive power of the gases generated during putrefaction, should this condition be present. Wounds made by _double shots_, as from double-barrelled guns, or pistols, or from slugs fired from one barrel, diverge after their entrance into the body.