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
surrounding tissues, the result of the injury, is gradually absorbed, and
the effused lymph, which is ultimately to constitute the temporary
cartilage, takes it place. In the second stage, from the tenth to the
twentieth day, the tumor or callus is formed and fibrocartilage is
developed inside and around the exposed end of the bone. In the third
stage, extending from the twentieth to the fortieth or fiftieth day,
according to the age and strength of the animal, the fibrocartilaginous
structure undergoes a change and is gradually converted into bone, forming
a ferrule on the