movement will be the same for each
leg and for each biped, whether the act is that of walking or trotting,
or even of galloping. In short, the regular play of every part of the
apparatus will testify to the existence of that condition of orderly
soundness and efficient activity eloquently suggestive of the condition
of vital integrity which is simply but comprehensively expressed by the
terms health and soundness.

But let some change, though slight and obscure, occur among the elements
of the case; some invisible agency of evil intrude among the harmonizing
processes going forward; any disorder occur in the relations of
cooperating parts; anything appear to neutralize the efficiency of
vitalizing forces; any disability of a limb to accept and to throw back
upon its mate the portion of the weight which belongs to it to
sustain--present itself, whether as the effect of accident or otherwise;
in short, let anything develop which tends to defeat the purpose of
nature in organizing the locomotive apparatus and we are confronted at
once by that which may be looked upon as a cause of lameness.

Not the least of the facts which it is important to remember is that it
is not sufficient to look for the manifestation of an existing
discordance in the action of the affected limb alone, but that it is
shared by the sound one and must be searched for in that as well as the
halting member, if the hazard of an error is to be avoided. The mode of
action of the leg which is the seat of the lameness will vary greatly
from that which it exhibited when in a healthy condition, and the sound
leg will also offer important modifications in the same three
particulars before alluded to, to wit, that of resting on the ground,
that of its elevation and forward motion, and that of striking the
ground again when the full action of stepping is accomplished. Inability
in the lame leg to sustain weight will imply excessive exertion by the
sound one, and lack of facility or disposition to rest the lame member
on the ground will necessitate a longer continuance of that action on
the sound side. Changes in the act of elevating the leg, or of carrying
it forward, or in both, will present entirely opposite conditions
between the two. The lame member will be elevated rapidly, moved
carefully forward, and returned to the ground with caution and
hesitancy, and the contact with the earth will be effected as lightly as
possible, while the sound limb will rest l