A Handbook of Health | Page 5

of all the
force and energy and power in this world, the sun.
That is why plants will, as you know, flourish and grow strong and
green only in the sunlight, and why they wilt and turn pale in the dark.
When the plant grows, it is simply sucking up through the green stuff
(chlorophyll) in its leaves the heat and light of the sun and turning it to
its own uses. Then this sunlight, which has been absorbed by plants and
built up into their leaves, branches, and fruits, and stored away in them
as energy or power, is eaten by animals; and they in turn use it to grow
and move about with.
Plants can use this sun-power only to grow with and to carry out a few
very limited movements, such as turning to face the sun, reaching over
toward the light, and so on. But animals, taking this power at
second-hand from plants by eating their leaves or fruits, can use it not
merely to grow with, but also to run, to fight, to climb, to cry out, and
to carry out all those movements and processes which we call life.
Plants, on the other hand, are quite independent of animals; for they can
take up, or drink, this sun-power directly, with the addition of water
from the soil sucked up through their roots, and certain salts[1] melted
in it. Plants can live, as we say, upon non-living foods. But animals
must take their supply of sun-power at second-hand by eating the
leaves and the fruits and the seeds of plants; or at third-hand by eating
other animals.
[Illustration: WHERE SUN-POWER IS MADE INTO FOOD FOR

US]
All living things, including ourselves, are simply bundles of sunlight,
done up in the form of cabbages, cows, and kings; and so it is quite
right to say that a healthy, happy child has a "sunny" disposition.
Plants and Animals Differ in their Way of Taking Food. As plants take
in their sun-food and their air directly through their leaves, and their
drink of salty water through their roots, they need no special opening
for the purpose of eating and drinking, like a mouth; or place for
storing food, like a stomach. They have mouths and stomachs all over
them, in the form of tiny pores on their leaves, and hair-like tubes
sticking out from their roots. They can eat with every inch of their
growing surface.
But animals, that have to take their sun-food or nourishment at
second-hand, in the form of solid pieces of seeds, fruits, or leaves of
plants, and must take their drink in gulps, instead of soaking it up all
over their surface, must have some sort of intake opening, or mouth,
somewhere on the surface; and some sort of pouch, or stomach, inside
the body, in which their food can be stored and digested, or melted
down. By this means they also get rid of the necessity of staying rooted
in one place, to suck up moisture and food from the soil. One of the
chief and most striking differences between plants and animals is that
animals have mouths and stomachs, while plants have not.
THE DIGESTIVE SYSTEM
How the Food Reaches the Stomach. Our body, then, has an opening,
which we call the mouth, through which our food-fuel can be taken in.
A straight delivery tube, called the gullet, or esophagus, runs down
from the mouth to a bag, or pouch, called the stomach, in which the
food is stored until it can be used to give energy to the body, just as the
gasoline is stored in the automobile tank until it can be burned.
The mouth opening is furnished with lips to open and close it and assist
in picking up our food and in sucking up our drink; and, as much of our
food is in solid form, and as the stomach can take care only of fluid and

pulpy materials, nature has provided a mill in the mouth in the form of
two arches, of semicircles, of teeth, which grind against each other and
crush the food into a pulp.
[Illustration: THE FOOD ROUTE IN THE DIGESTIVE SYSTEM
In this diagram the entire alimentary canal is shown enlarged, and the
small intestine greatly shortened, in order to show distinctly the course
of the food in the process of digestion.]
In the bottom or floor of the mouth, there has grown up a movable
bundle of muscles, called the tongue, which acts as a sort of waiter,
handing the food about the mouth, pushing it between the teeth, licking
it out of the pouches of the cheeks to bring it back into the teeth-mill
again, and finally, after it has been reduced to a pulp, gathering it up
into a little