either directly or indirectly-- through other animals,
in the case of meat-eaters-- from the vegetable kingdom.
As the student will learn early in his botanical reading, the typical
plant has, in its green colouring matter, chlorophyll, a trap to catch
the radiating energy of the sun, and to accomplish, by the
absorption of that energy, the synthesis (building up) of those
organic compounds which the animal destroys. The typical plant is,
on whole, passive and synthetic, or anabolic; the typical animal,
active and katabolic; and the excess of kataboly over anaboly in the
animal is compensated for by the anabolic work stored up, as it
were, by the plant, which is, directly or indirectly, the animal's food.

2. _The Alimentary Canal of the Rabbit_

Section 16. Figure 1 represents the general anatomy of the rabbit,
but is especially intended to show the alimentary (= food) canal,
shortened to a certain extent, and with the proportions altered, in
order to avoid any confusing complications. It is evidently simply a
coiled tube-- coiled for the sake of packing-- with occasional
dilatations, and with one side-shunt, the caecum (cae.), into which
the food enters, and is returned to the main line, after probably
absorbent action, imperfectly understood at present. A spiral fold in
this cul-de-sac {bottom-of-sack}, which is marked externally by
constrictions, has a directive influence on the circulation of its
contents. The student should sketch Figure 1 once or twice, and
make himself familiar with the order and names of the parts before
proceeding. We have, in succession, the mouth (M.), separated from
the nasal passage (Na.) above the palate; the pharynx (ph.), where
the right and left nasal passages open by the posterior nares into
the mouth; the oesophagus (oes.); the bag-like stomach, its left
(Section 6) end being called the cardiac (cd.st.), and its right the
pyloric end (py.); the U-shaped duodenum (ddnm.) and the very long
and greatly coiled ileum (il.). The duodenum and ileum together form
the small intestine; and the ileum is dilated at its distal end into a
thick-walled sacculus rotundus (s.r.), beyond which point comes the
large intestine. The colon (co.) and rectum (r.) continue the main line
of the alimentary canal; but, at the beginning of the large intestine,
there is also inserted a great side-shunt, the caecum (cae.), ending
blindly in a fleshy vermiform appendix (v.ap.). The figure will indicate
how th