In a normal state of things the legs perform their movements with the
joints as their only centers or bases of action, with no participation
of intermediate points, while with a fracture the flexibility and motion
which will be observed at unnatural points are among the most strongly
characteristic signs of the lesion. No one need be told that, when the
shaft of a limb is seen to bend midway between the joints, with the
lower portion swinging freely, the leg is broken. There are still some
conditions, however, in which the excessive mobility is not easy to
detect. Such are the cases in which the fracture exists in a short
bone, near a movable joint, or in a bone of a region where several short
and small bones are united in a group, or even in a long bone the
situation of which is such that the muscular covering prevents the
visible manifestation of the symptom.

If the situation of a fracture precludes its discovery by means of this
abnormal flexibility, other modes of detection remain. There is one
method which is absolute and positive and which can be applied in by far
the most, though not in all cases. This is crepitation, or the peculiar
effect which is produced by the friction of the fractured surfaces one
against another. Though discerned by the organs of hearing it can
scarcely be called a sound, for the grating of the parts as the rubbing
takes place is more felt than heard; however, there is no mistaking its
import in cases favorable for the application of the test. The
conditions in which it is not available are those of incomplete
fracture, in which the mobility of the part is lacking, and those in
which the whole array of phenomena are usually obscure. To obtain the
benefit of this pathognomonic sign requires deliberate, careful, and
gentle manipulation. Sometimes the slightest of movements will be
sufficient for its development, after much rougher handling has failed
to discover it. Perhaps the failure in the latter case is due to a sort
of defensive spasmodic rigidity caused by the pain resulting from the
rude interference.

More or less reactive fever is a usual accompaniment of a fracture.
Ecchymosis in the parts is but a natural occurrence, and is more easily
discovered in animals possessing a light-colored and delicate skin than
in those of any other character.

There are difficulties in the way of the diagnosis of an incomplete
fracture, even sometimes when there is a degree of impairment in the