outside and a plug on the inside, which serve to hold the
part in position. In the fourth stage, extending to about the sixth month,
the whole of the new structure is converted into bone. In the fifth stage,
extending to the end of the first year, the callus is absorbed, being no
longer necessary, and the connection between the cavities of the two bones
is again established.

_Common complications._--The process of union just described is healthy and
normal. Diseased conditions may at any time supervene during the treatment
and render the operation unsuccessful. In the case of compound fracture,
the open wound communicating with the ends of the bones, a septic condition
is liable to arise which may become so serious as to endanger the animal's
life and bring about conditions which in human surgery would indicate
amputation. Although that operation is not a general one in veterinary
practice, there is no reason why it should not be attempted as a last
resort, particularly if the animal is valuable or is one whose existence is
necessary in order to perpetuate some valuable strain. Even in the simplest
form of fracture, if the splints or bandages are improperly applied and the
fractured bone left so loosely guarded that the broken ends move one upon
another, the formation of the calluses previously described is liable to be
interfered with, and in place of a strong, rigid, and healthy union a
formation of elastic cartilage is the result. This false structure unites
the broken ends of the bones in such way that they move one upon another,
depriving the bone of its stability and usefulness. When once the healthy
process of union is interrupted in the manner just described, it is again
established with great difficulty. It no longer does any good to continue
the restraining power; in fact, the change of the temporary cartilage into
bone is more liable to be reestablished if the parts move violently upon
each other for a short time so as to set up and renew the process of
inflammation. Then if the restraint is again applied there is some chance
of union. In order so far as possible to avoid this danger, care should be
taken to see that the bandage fits closely and that it is kept on till
there is no longer any danger but that a perfect union has taken place. It
is impossible to say at just what time the splints or bandages can safely
be removed. In a young and healthy animal of quiet temperament, if the
parts have been firmly he