seek to preserve his health from day to
day, but he should so manage his body as to use his powers to the best
advantage and prolong as far as possible the period during which he may be
a capable and useful citizen.

CHAPTER II - GENERAL VIEW OF THE BODY

*External Divisions.*--Examined from the outside, the body presents certain
parts, or divisions, familiar to all. The main, or central, portion is
known as the _trunk_, and to this are attached the _head_, the _upper
extremities_, and the _lower extremities_. These in turn present smaller
divisions which are also familiar. The upper part of the trunk is known as
the _thorax_, or chest, and the lower part as the _abdomen_. The portions
of the trunk to which the arms are attached are the _shoulders_, and those
to which the legs are joined are the _hips_, while the central rear
portion between the neck and the hips is the _back_. The fingers, the
hand, the wrist, the forearm, the elbow, and the upper arm are the main
divisions of each of the upper extremities. The toes, the foot, the ankle,
the lower leg, the knee, and the thigh are the chief divisions of each of
the lower extremities. The head, which is joined to the trunk by the neck,
has such interesting parts as the eyes, the ears, the nose, the jaws, the
cheeks, and the mouth. The entire body is inclosed in a double covering,
called the _skin_, which protects it in various ways.

*The Tissues.*--After examining the external features of the body, we
naturally inquire about its internal structures. These are not so easily
investigated, and much which is of interest to advanced students must be
omitted from an elementary course. We may, however, as a first step in
this study, determine what kinds of materials enter into the construction
of the body. For this purpose the body of some small animal should be
dissected and studied. (See observation at close of chapter.) The
different materials found by such a dissection correspond closely to the
substances, called _tissues_, which make up the human body. The main
tissues of the body, as ordinarily named, are the _muscular_ tissue, the
_osseous_ tissue, the _connective_ tissue, the _nervous_ tissue, the
_adipose_ tissue, the _cartilaginous_ tissue, and the _epithelial_ and
_glandular_ tissue. Most of these present different varieties, making all
together some fifteen different kinds of tissues that enter into the
construction of the body.(2)

*General Purposes of