Wound of the epigastric artery is the chief danger, for in _all_ cases it is close to the neck of the sac. Were its position in relation to the neck of the sac constant, it might be easily avoided by an incision in the opposite direction; but as this relation varies according to the nature of the hernia, an element of danger is introduced. Thus, in oblique inguinal ruptures, where the sac passes out through the internal ring (Fig. XXXII. IR), the artery will always be found to the inside of the neck of the sac; while in direct herniæ, where the bowel has made its escape through the triangle of Hesselbach (Fig. XXXII. +), and passed through the conjoint tendon straight to the external ring, the epigastric artery will be found on the outside of the neck of the sac. In recent herniæ the differential diagnosis is comparatively easy, but in those of old standing and large size, in which the obliquity of the canal has been much diminished, it is almost impossible to tell of what kind the hernia originally was, and consequently to determine in which direction it is safe to incise the neck of the sac. Such being the case, the best rule is to incise the neck of the sac directly upwards, _i.e._ in a line parallel with the linea alba, and also to cut it very cautiously bit by bit, in every case, if possible, with the finger inserted as a guide to the position of a vessel and a protection to the gut. The spermatic vessels lie sometimes behind, sometimes on either side of the sac, and in very old herniæ may be separated from each other so as really to surround the sac. The cut directly upwards is also the safest for them. All constrictions being overcome, it is not sufficient merely to push back the gut into the belly. Its condition must be carefully examined, and it must be decided whether the constriction has caused gangrene or not. To examine this properly, it is generally best to pull down an inch or two more of the gut, so as thoroughly to bring into view the constricted portion, as _it_ is most likely to be fatally nipped. It is not always easy to decide as to the condition of the bowel. Certain points must be observed:-- (1.) _Colour._--There may be very great alteration in the colour of the bowel from congestion, and yet no gangrene. It may be dark red, claret, purple, or even have a brownish tint, and yet recover; where it is black, or a deep brown, the prognosis is unfavourable. (2.) _Glistening._--So long as the proper glistening appearance of the bowel remains, there is hope for it, even when the colour is bad; if it has lost it, and especially if, instead of being tense and shining, it is dull and flaccid and in wrinkles, the bowel is almost certainly gangrenous. (3.) _Thickness._--If much thickened, and especially if rough on the surface, the bowel has probably been forming adhesions to the sac, or to contiguous coils, and the prognosis is less favourable.