Fig. 25 (_a_), A (plate I.) represents a section carried across an aseptic aperture of entry. The specimen was removed by Mr. Cheatle from a patient who died forty-eight hours after reception of the injury. It shows well the small amount of gross destruction suffered by the subcutaneous tissue, and the rapid repair which follows, since macroscopically the track is scarcely discernible. Reference to plate I. shows the remarkable fact that even at this early date considerable progress towards definite healing has occurred, and a thin layer of stratified epidermis covers the original opening. The question may be raised whether the origin of this epidermal layer is not in part a floating up of the margins of the main aperture. During the course of healing some variation takes place in the appearance of the apertures, especially that of entry. This, at first contracted, later becomes somewhat relaxed, while in many cases a small halo of ecchymosis develops around it. The blood-clot occupying its centre now contracts, the margins rapidly become approximated centripetally, and a small circular dark spot only remains, which is later replaced by a small red cicatrix. The dark central spot under these circumstances consists of the contused margin of the wound in the skin, and a small proportion of blood-clot which finally comes away as a small dry scab. When slight local infection occurs in place of simple contraction and dry scabbing, the process is prolonged, the contused margin separates by granulation, the clot in the opening breaks down, and a small ulcer of somewhat larger proportions than the original wound remains and takes some days to heal. [Illustration: FIG. 25 (_a_).--_A._ Wound of entry 48 hours after reception. _B._ Wound of exit, 7-1/2 days after reception. 1. Skin. 2. Subcutaneous fat carried into the lips of the wound by the bullet. 3. Infected blood extravasation in subcutaneous tissue. Exact size. (See plates I. and II.)] The aperture of exit in simple wounds of the soft parts sometimes heals even more rapidly than that of entry, and if of the slit form may be almost invisible at the end of ten days or a fortnight, actual primary union having taken place as after a simple small incision. Larger or irregular exit apertures, however, take a longer period to close than entry wounds, and this is most often observed when the bullet has undergone deformation within the body, or bone fragments have been driven out with the bullet.