THE ABDOMEN
The hinder part of the bee’s body is called the abdomen, and it is
here that the stomach is situated. The abdomen is larger than either
the head or the thorax, and is joined to this latter by a thin waist.
Insects do not possess skeletons, at least not internal skeletons of
bones, such as we have. Their skeletons are outside the body, and
take the form of a hard outer layer which protects the soft inner
organs. This layer, or outer skin, is made of a horny substance, called
_chitine_ (pronounced “ki-tin”), which comes from a Greek word meaning
a tunic or outer dress.
Chitine is indeed a wonderful substance, and is found in all forms
and shapes, having a variety of appearances. The hard black bodies of
beetles are composed of it, and, wonderful to relate, of this substance
the downy wings of the butterfly are made. You will remember that
in the chapter on the eye of the bee we saw that the facets have a
beautiful appearance; they too are made of chitine, as are the tendons,
legs, hairs, membranes, and many other parts of the body.
The abdomen of the queen and of the worker is divided into six rings
or belts, but the drone, having a somewhat larger body, has seven.
Each ring is divided again into two parts which are known as the
_scelerites_, which are joined one to another by delicate membranes of
very fine skin. You may have noticed that the leg of a crab is jointed,
and that the hard outer case of shell gives place to a fine, but tough
membrane at the joints. By means of this arrangement the crab can move
its leg with ease. The joints of the abdomen of the bee are arranged
in a similar manner, although in this case the membranes are of course
much finer and more delicate than those of the crab.
The organs inside the outer case of chitine are of most wonderful and
delicate construction. You may be surprised and interested to learn
that a bee has two stomachs, and these are perhaps the most important
parts of the abdomen. It is not because the bee is a greedy insect that
it is provided with two stomachs, but each serves a separate and useful
purpose. One is called the honey-sac, and the other is the stomach
proper. As a bee sips the nectar from a flower, it is passed down a
tube through the thorax into the honey-sac, which acts as a kind of
store-chamber. Here it is kept until the bee flies back to the hive, or
until the little worker may need it for its own food. Leading from the
honey-sac to the stomach is a very fine tube, and at the honey-sac end
of it there is a kind of stopper, called the “stomach mouth.” Just as
we can open or close our mouths at will, so can the bee open or close
the stomach mouth, and so either allow honey to flow into its true
stomach or keep it stored in the honey-sac. The latter is very tiny,
and when quite full contains little more than a third of an ordinary
drop of honey. The tube which leads from the one to the other is lined
with fine hairs, all pointing in a downward direction, away from the
honey-sac. When the bee sips the nectar it often happens that some
of the pollen grains from the flower are taken in also. Now the bee
desires to gather only the pure nectar, and so it passes the nectar
from the honey-sac to the stomach by means of the tube. It then makes
the honey return from the stomach to the honey-sac, but this time the
hairs in the tube act as a strainer, and prevent the pollen grains from
returning with the nectar. By this clever little apparatus you will
see that the bee is able to strain the nectar when flying from one
flower to another, or when travelling back to the hive. Besides the two
stomachs, the abdomen contains certain glands to which we shall refer
when we come to speak of honey.