_Modes of union._--The animal should be kept as quiet as possible and given such feed as will have a tendency to keep the bowels slightly relaxed. The success of the operation depends chiefly on the skill of the operator, but not alone in the selection and use of the appliances, for as much attention must be given to subsequent management. The patients are restless, and a single awkward motion may undo the work of weeks so far as the union of the parts of the bone is concerned. Union takes place after the same process and, if the conditions are favorable, with greater rapidity than in the human being. The injury that caused the fracture is almost sure to have extended to some of the adjacent tissues, and even though the fracture may be of the simplest type there is almost sure to be considerable hemorrhage around the ends of the broken bone. This, however, is unimportant if the skin remains intact, unless a very large vessel should be injured, or the fracture should open some of the important cavities of the body, in which case a fatal hemorrhage may result. If, on the other hand, the fracture is compound the external opening furnishes a fertile field for the lodgment of disease-producing germs. Unless great care is taken in such cases, a suppurative process is liable to be established which will seriously interfere with, if not entirely arrest, the process of union between the bones; or it may become so serious as to endanger the general health of the animal and even be attended with fatal results. This last danger is greater if the injury has occurred to the bones of the arm or thigh. In such cases, owing to the dense covering of fascia which ensheathes the muscular covering pus is liable to be imprisoned, and, burrowing downward, saturate the whole structure, not only endangering the limb, but, by absorption, may set up blood poisoning and seriously interfere with the general health of the patient, even to causing death. In order so far as possible to prevent such an unfortunate complication, the wound should be carefully cleansed with a mild solution of carbolic acid, then dusted over with iodoform before the bandages are applied, and cleansed and dressed daily in the same way. After dressing, always cover with absorbent cotton. In the early process of union an exudation of lymph takes place, which is at first fluid, gradually becoming thicker and firmer till it forms a callus, known as the external or ensheathing callus, in the shape of a ring or ferrule surrounding the detached portions of the bone. It occasionally happens that this callus forms only at the ends of the bones, filling the spaces that exist between them, when it is known as the intermediate callus. The process of union may be divided into five stages. In the first stage, including the first eight days, the detached portions of the bone and the sharp projections that are not sufficiently nourished are absorbed; the blood which escaped into the