be
solved."

A BIRD'S FOOT

You will agree with me, after you have studied a bird's foot, that it
is one of Nature's most wonderful contrivances, so admirably adapted
for the purposes to which it is devoted that one cannot help feeling
that a Divine Mind must have planned it, just as a man would make a
watch for the express purpose of keeping time.

But what is properly included in a bird's foot? Here we shall have to
correct a popular mistake, if we wish to be accurate, in the scientific
sense of the term. Most people think that the avian foot consists only
of the toes and claws, or the part that comes in direct contact with
the ground or the perch. That, however, is an error, for the foot
really comprises, in addition to the toes and claws, the first long
bone of the limb, reaching from the base of the digits to the first
joint. You will see, therefore, that the bird walks on its toes, not
on its foot as a whole.

The long bone referred to--called the tarsus--corresponds to the instep
of the human foot, that is, the foot proper, while the joint which
extends backward, forming an angle with the next large bone, is really
the bird's heel. Thus you perceive that most birds walk with their
heels high in the air. What most people call the bird's "leg" is in
reality the bird's foot, and what they call its "foot" comprises only
its toes and claws.

To obtain a correct idea of the bird's entire walking apparatus, we
begin with the uppermost part of the leg. As we proceed, it would be
well to keep in mind the different parts of the human leg and foot.
The highest bone is called the thigh bone or femur, which is, for the
most part, enclosed in the general integument of the body, and is not
entirely separate from it as is the thigh bone of the human leg. Among
carvers it is known as the "second joint." It reaches forward and
slightly downward, and is hidden under the feathers of the body. The
upper end of the femur enlarges into a globular head, which fits into
the socket of the hip in the pelvis, while the lower end meets another
long bone, which extends obliquely backward and downward and with which
it forms the knee joint.

The knee of the bird extends forward, as the human knee does when it is
bent. By means of various nodules and tendons the femur is articulated
with and fastened to the next large bone at the knee joint. This
second bone is the leg proper, called in scientific language the crus.