They advance steadily on all sides, filling the gaping wound until the level of the original surface is reached, the new tissue organizing behind them, and contracting as it organizes, so that the space to be filled is daily made smaller by this contraction as well as by the production of new tissue. As the surface is reached, the epithelial cells on the edges of the granulating area slowly spread over it, the granulations generally projecting above the adjoining surface and the epithelium growing over them as they contract again to their proper level. The advancing line of epidermis is visible as a pink line, gradually whitening with time. CHAPTER V +WOUNDS AND CONTUSIONS+ A wound is a solution of continuity or division of the soft tissues produced by cutting, tearing, or compressing force. The classification of wounds according to their causation or nature is as follows: _Incised_—when resulting from a sharped-edged instrument. _Lacerated_—when tissues are extensively torn or separated. _Contused_—when resulting from a more diffused force, tearing and bruising the tissues. _Punctured_—when produced by a narrow instrument that causes a wound deeper than its external surface is broad. _Poisoned_—when some poisonous substance enters the wound and causes local infection or constitutional disturbance. _Gunshot_—when the injury results from firearms or powder explosion. +An Incised Wound+ is an injury which is produced by some sharp instrument such as a knife, pieces of glass or metal, which divides the tissues cleanly, producing no bruising or tearing. The pain is usually sharp and burning, varying with the nature of the instrument with which the injury has been inflicted. Hemorrhage is usually free. +Lacerated Wounds.+ These usually result from machinery accidents or from heavy bodies passing over the parts and are apt to contain a considerable quantity of foreign matter ground into the tissues. +Contused Wounds.+ A contused wound is one in which the edges and surrounding tissues are bruised or crushed. External bleeding as a rule is not excessive, although there is a great likelihood of extensive subcutaneous hemorrhage. Sloughing and gangrene may occur. +Punctured Wounds.+ The character of a punctured wound depends upon the object producing it. If made by sharp instruments, such as knives, swords, daggers, bayonets, or needles, their nature is similar to incised wounds.