Venesection is an easy operation for a physician who has already familiarized himself with the manner of performing it, but for one who is ignorant of these details it may prove very difficult. It is necessary, for example, to bear in mind that the artery and vein are united and that they are accompanied by nerves; and, further, that the injuring of the latter will induce spasms and violent pains. On the other hand, it must also not be forgotten that an artery once opened has no disposition to close, nor does it heal, and that sometimes the blood escapes in an impetuous manner. If, perchance, the vein is cut transversely, the edges of the opening contract and no more blood escapes. Again, if the scalpel is plunged into the parts timidly, the skin alone will be divided and the vein will not be opened. In some cases this vessel is so hidden from sight that the physician may experience difficulty in bringing it into view. Thus it will be seen that there are several circumstances which may render this operation difficult for an ignorant or inexperienced physician. The vein should be incised in a longitudinal direction, midway between its two sides. The moment the blood gushes from the opening its color and general appearance should be carefully noted, etc. _Book V., Chapter XXVI._--_The Proper Manner of Arresting Hemorrhage from a Wound._--If there is fear that there may be bleeding, one should fill the wound with dry lint, place over it a sponge wrung out of cold water, and press upon it with the hand. If the bleeding still continues, it is advisable to change the stuffing of lint somewhat frequently; and, if this step proves ineffective, then lint moistened with vinegar may be tried, for this liquid acts energetically in arresting hemorrhage. Some physicians, indeed, actually pour it into the wound. There is a strong objection, however, to the use of an agent which, like vinegar, arrests the bleeding too completely--viz., that it is apt to set up afterwards an intense inflammation of the parts. The same reasoning applies with even greater force to the employment of corrosives and caustics, which produce an eschar. Despite the effectiveness of most of these in arresting hemorrhage, their use should be discouraged.... Finally, if the bleeding continues it will be necessary to grasp the vessel from which the blood is escaping, to ligature it in two places close to the wound, and then to divide the vessel between the two ligatures, in order that it may retract (both of the new orifices having already been closed by the ligatures). If the circumstances are such that the plan just recommended cannot be carried out, it will then be advisable to apply the red-hot cautery to the bleeding vessel. When a rather free hemorrhage occurs at a part of the body where