out from them of itself, on the least movement of the jaw, which presses
upon the sponges as it goes up and down. The name of this water, as
I need scarcely tell you, is _saliva_.

When I call it water, it is not merely from its resemblance; _saliva_ is
really pure water with a little _albumen_ added. Do not be afraid of
that word--it is not so alarming as it appears to be. It means simply
the substance you know as the _white of egg_. There is also a little
soda in the water, which you know is one of the ingredients of which
soap is made. And this explains why the saliva becomes frothy, when the
cheeks and tongue set it in motion in the mouth while we are talking;
just as the whites of egg, or soapy water, become frothy when whipped up
or beaten in a basin.

But the albumen and the soda have not been added to the saliva, in our
case, merely to make it frothy; that would have been of very little
use. They give to the water a greater power to dissolve the food into
paste, and thus to begin that series of transformations by which it
gradually becomes the fine red blood which shows itself in little drops
at the tip of your finger when you have been using your needle
awkwardly.

When once minced up by the teeth and moistened by the saliva, the food
is reduced to a state of pulp, and having nothing further to do in the
mouth, is ready to pass forward. But getting out of the mouth on its
journey downwards is not so simple an affair as getting into it by the
_front door_, as it did at first. Swallowing is in fact a complicated
action, and not to be explained in half a dozen words, and I think we
have already chatted enough for to-day. I only wish I may not have tired
you out with these interminable teeth! But you may expect something