traversed the wounded part materially influenced the extent to which the special qualities of the structures traversed could be exerted. It was accepted as a general rule, that when a bullet maintains its direct course, the higher the rate of speed the more direct is the track, and the more complete is the destruction of all the parts opposed to its passage, whatever their nature.

While considering the principal causes of the absence of uniformity in the tracks of projectiles through parts of the body, one other circumstance which helps to produce such irregularities should be named. Whatever may be the position of a limb, or inclination of a part of the body, at the instant it is traversed by a missile, a change of attitude of the wounded man at once changes. the relative positions of the various structures composing the parts concerned in the injury. The change which takes place in the regularity of the internal wound from this simple cause is often much greater than might be anticipated.

The characters of all gunshot wounds become materially altered in respect to shape, size, and amount of laceration, if the projectile has been caused to traverse the tissues in any other than the normal direction on its long axis; as when an elongated bullet has been caused to pass through them while rotating on one of its short axes, or has ricochetted from a stone, gravel, or other hard substance on the ground. Some of the effects of such accidental alterations in the manner of flight of bullets upon wounds have been already noticed when the subject of the dimensions of bullets was under consideration in a preceding section of this work.

It is useful still to be acquainted with the general characteristics of the openings made in the several anatomical structures through which one of the older forms of cylindro-conoidal bullets had effected a passage. The same effects may be observed, though more or less modified according to circumstances, when some of the projectiles in use at the present day inflict wounds.

Bullet openings in fascia.-When the structures composing a part of the body through which a bullet has passed are separately examined, much diversity will be observable in the shapes and sizes of the openings made in them by the projectile. When an Enfield or Martini-Henry bullet has inflicted a flesh wound through a part of one of the extremities-the thigh for example-while maintaining its ordinary mode of flight, and retaining an average rate of speed, the first part of the track will usually feel constricted as compared with the parts beyond. This may sometimes be due to contraction of the opening through the skin and superficial fascia, but is more generally the result of the peculiar slit-like opening through the aponeurotic fascia beneath. The opening through this fascia is usually very little due to actual removal of its substance, but is principally brought about by division of some, and separation with temporary displacement of

others, of its principal parallel fibres. The tendinous fibres, thus displaced, being afterwards put on the stretch by muscular action, or by movement of parts beyond the seat of injury, or by simple alteration in position of the part of the body concerned, are then caused to approach each other, and thus to narrow and contract the opening. The bullet probably pushes before it the resisting fascia upon the soft tissues below, until the connective tissue uniting the principal longitudinal fibres gives way, and allows the greater part of them in front of the bullet to yield to each side, very few of the longitudinal fibres being actually divided; while the crossing fibres of a weaker description are either, as mostly happens, torn asunder, or are similarly separated by the destruction of their connections. The bullet opening is thus converted either into a kind of torn or fringed slit, the direction of which corresponds with the direction of the principal and strongest fibres of the fascia at the seat of injury, or into a more or less rectangular aperture bounded on each side by the crossing tendinous fibres which have been left entire, like the square opening which is seen in a piece of canvas through which a round bullet has been fired. An opening closely resembling the mere slit first mentioned has been observed in the fibrous structure constituting the anterior common ligament of the vertebral column after the passage of a bullet. M. Legouest has recorded that he saw a case in which a projectile of small volume had penetrated the body of a vertebra from the front. The vertical fibres of the covering of the bone, after being traversed by the projectile, closed toward each other, so as to conceal the penetration and the fact of its presence in the body of the bone.25 Occasionally, however, a cylindro-conoidal bullet, probably when it was armed with a very high rate of velocity, and sufficient time was not allowed for the fibres to move aside out of the way of the projectile, left an opening which was no longer of the nature of a slit, but closely corresponded with the shape of the projectile. This will probably be the general character of the openings left in fascial structures after penetration by smallbore projectiles, owing to their immense penetrative power at all ordinary distances.

Bullet openings in deep aponeuroses.-The deep aponeuroses and intermuscular ligamentous tissues, the sheaths of many muscles, are affected by the passage of projectiles in a similar way to the fascia investing the superficial parts of the body. The fibres of the sheath of a muscle may be so acted upon by a cylindroconoidal bullet passing through it at a medium rate of speed as to be simply torn asunder and separated from each other, and thus, on being drawn together again by some cause, may cover up the hole which has been made in the muscular tissue. But if the sheath of the muscle be dense on the opposite aspects of a thick muscle, as happens in the rectus, and in some of the muscles of

the extremities, the part of the sheath through which the bullet first penetrated is acted upon differently from that which is last perforated. The front of the sheath pressed towards the muscle retains its connection with it around the track of the bullet, a few of the principal fibres being torn across and their ends curled up, but not extending beyond the margin of the opening in the muscle; while on its posterior aspect, where it is pressed from the muscle, the sheath is more or less torn away from its connections, and the fibres of the sheath extensively separated from each other. The front opening therefore often appears more circular and limited, the posterior more elongated. The same difference is met with in the openings of the aponeurotic fascia on the two opposite sides of a perforated limb. At the opening of entrance the connections of the fascia with the structures which it covers are but little disturbed, and the opening is more contracted in size than the opening of exit through the fascia on the other side. The opening of exit is rendered more free by being forced away from its connections with the muscles to which it was previously attached, and by its fibres being more extensively torn asunder. On holding to the light a portion of fascia through which one of the cylindro-conoidal bullets used with the Enfield or Martini-Henry rifles had made its exit-the fascia-lata of the thigh for example-the separation of the longitudinal fibres might be seen to extend considerably beyond the actual opening, though they were still held loosely together by crossing fibres of a weaker description and by connective tissue.

Long tendons, nerves, and blood-vessels in bullet tracks.Tendons have hitherto exhibited a remarkable immunity from division by bullets. They have frequently escaped division, though subsequently they were felt to be in the course which the bullet had taken. They must in many such cases have been pushed aside, and then have returned to their previous position, thus interfering with the continuity of the direct track so far as observation of the wound by a finger was concerned. In like manner other long and mobile structures, though not possessing equal strength and tenacity, as nerves and blood-vessels, used frequently to escape without being divided. When a bullet strikes direct upon and passes through a broad tendon like the ligamentum patellæ, the opening left is well defined, but, owing to the elasticity of the tendinous fibres, appears to be smaller in diameter than the diameter of the bullet by which it was caused. On the other hand, the divided ends of a narrow tendon which has happened to be partially or entirely cut across under like circumstances, usually present surfaces which are much torn and very irregular, perhaps from having been divided by the bullet against a bone, or from having been greatly stretched before giving way to the opposing force. Experiments with the new

narrow bullets seem to prove that long tendons, however tough, are not likely to be pushed aside by them so long as they retain their high rates of velocity, but that they will in most instances be either perforated or divided by them.

Bullet openings in adipose tissue and muscles.-The common cellular adipose tissue, offering little resistance against perforation, presents an opening corresponding with the size of the bullet, or, if any alteration in size occurs, the change depends probably more upon the qualities and movements of adjoining structures than upon any action of the cellular tissue itself.

The substance of the muscular structures also is endowed with but little power of resistance against the forcible passage of a bullet. The part directly opposed to the projectile is compressed, disintegrated, and carried away in front of it, or dispersed in the surrounding tissue. Sometimes a large hole irregular in shape and size, sometimes a canal-like opening, is left through its substance. The condition of the track left by the bullet is probably modified to a certain extent by the condition the muscles happened to be in at the time of the passage of the projectile. A muscle in an active state of contraction, or passively stretched, will present a more firm and resisting front to the projectile than a muscle in a condition of relaxation. There will be more complete destruction and removal of substance, therefore, in the two former states of the muscle than in the latter. In the relaxed condition of the muscle there will be more stretching and tearing, and more return of its fibres upon the opening through which the projectile had passed. The track will be again modified in its characters when the state in which the muscle happened to be at the time of perforation is afterwards changed; when the stretched muscle resumes its ordinary state of repose, and the contracted muscle returns to a state of relaxation.

The large gaps occasionally met with in muscles.-The reasons already given do not, however, suffice to explain the spacious gaps which were occasionally met with in muscular tissues wounded by the elongated bullets recently in use when these projectiles had appeared to preserve a direct line of flight. The probable explanation in these instances is that the wounds were inflicted by the projectiles very early in their course-when they had lost scarcely any of the destructive energy originally impressed upon them. How enormous this amount of energy was in the bullets in recent use, even at long distances from the rifle, may be seen in the table showing the vis viva retained by the MartiniHenry projectile at different points of its course. The active force of the most recent small-bore projectiles, as shown elsewhere, is considerably greater. Under such circumstances, just as when a bone is broken, its fragments become converted into so many projectiles, so even the fluid blood and the disintegrated particles of

muscular tissue may be propelled with force enough to act in the capacity of secondary missiles, and increase the area of laceration. When an animal near a wall is shot through the body, or through the fleshy part of a limb, by a rifle bullet at a very high rate of speed, one effect is that the wall is more or less widely splashed with a quantity of blood. This blood has been forced by the bullet through the wound of exit. The blood has received part of the momentum of the bullet, and has itself passed onwards with a large amount of force. If closely examined, there will be found also upon the wall and on the ground between it and the animal a quantity of particles of muscular pulp. The disintegrated muscle, like the blood, has acquired a certain velocity of movement from the projectile which has mashed it up, and itself has been turned into a projectile; as much as if tallow or any other soft material were fired direct from a fire-arm, or as water struck by a shot possessing great momentum is driven with considerable initial force from the site of impact. It seems only in this way that the large gaps can be explained which are occasionally effected in the muscles by elongated projectiles of small diameters when they have preserved their direct line of flight and only soft tissues have been traversed by them.

Effects on bullet tracks of collision with bone.-If the shaft of a bone happen to be struck, the whole track of a bullet becomes greatly changed. If the bone be unbroken, though grazed or slightly grooved, the line of the track is simply turned in another direction, unless the mode of rotation of the bullet be altered, when other changes, elsewhere explained, take place. If the bone be pierced through, but not splintered, no material change in the direction of the track is noticeable or occurs. If the bone be comminuted, the track is altered in size, shape, and condition, according to the situation of the bone broken and to the nature and circumstances of the fracture, especially in regard to the number and shapes of the fragments, and the extent to which they have been driven into the adjoining structures. The number and shapes of the fragments, and the distances to which they are driven, will mainly depend upon the amount of active force retained by the bullet that inflicts the injury; the size, power of resistance, and brittleness of the bone struck; and, to some extent, the qualities of the tissues by which it is surrounded, whether they be aponeurotic or thickly muscular. If a rifle bullet of toughened lead, such as the Martini-Henry, when armed with its full force, strike a hard and powerful long bone, like the femur for example, near the middle of its shaft, it is broken up into fragments, often too numerous to be counted, of various shapes and dimensions. A large proportion of these fragments are driven violently in various directions, and are thus converted into secondary missiles. They give rise to much the same kind