he action of two principal
systems of organs, known in anatomical and physiological terminology as
passive and active, the muscles performing the active and the bones the
passive portion of the movement. The necessary connection between the
cooperating parts of the organism is effected by means of a vital
contact by which the muscle is attached to the bone at certain
determinate points on the surface of the latter. These points of
attachment appear sometimes as an eminence, sometimes as a depression,
sometimes a border or an angle, or again as a mere roughness, but each
perfectly fulfilling its purpose, while the necessary motion is provided
for by the formation of the ends of the long bones into the requisite
articulations, joints, or hinges. Every motion is the product of the
contraction of one or more of the muscles, which, as it acts upon the
bony levers, gives rise to a movement of extension or flexion, abduction
or adduction, rotation or circumduction. The movement of abduction is
that which passes from and that of adduction that which passes toward
the median line, or the center of the body. The movements of flexion and
extension are too well understood to need defining. It is the
combination and rapid alterations of these movements which produce the
different postures and various gaits of the animal, and it is their
interruption and derangement, from whatever causes, which constitute the
pathological condition known as lameness.

A concise examination of the general anatomy of these organs, however,
must precede the consideration of the pathological questions pertaining
to the subject. A statement, such as we have just given, containing only
the briefest hint of matters which, though not necessarily in their
ultimate scientific minutiae, must be clearly comprehended in order to
acquire a symmetrical and satisfactory view of the theme as a practical
collation of facts to be remembered, analyzed, applied, and utilized.

It was the great Bacon who wrote: "The human body may be compared, from
its complex and delicate organization, to a musical instrument of the
most perfect construction, but exceedingly liable to derangement." In
its degree the remark is equally applicable to the equine body, and if
we would keep it in tune and profit by its harmonious action we must at
least acquaint ourselves with the relations of its parts and the mode of
their cooperation.

ANATOMY.

The bones, then, are the hard organs wh