aller places
are just like bottles, and are called _cells_.

So when a camel takes a good long drink, the big place in the middle
of the stomach takes in the water first; then as he drinks more and
more, the bottles or cells all around begin to get filled also. And
the wonderful thing is that as soon as each cell is full, its mouth
closes up by itself! In that way, if the camel drinks long enough, all
the cells get full, one by one, and then have their mouths closed up.

When a camel is about to start on a long journey through the desert,
he takes a very long drink, till he _feels_ that he cannot drink any
more; then he _knows_ that all the bottles or cells inside are quite
full, as well as the big place in the middle of his stomach. Now he is
ready to cross the desert.

After many hours all the water in the big place in the middle of the
stomach gets used up. Then what happens? Why, one of the bottles
inside opens its mouth by itself, and pours the water into the
stomach! And after many hours more, when _that_ water has also been
used up, the _second_ bottle opens its mouth and pours the water into
the stomach. In this way all the bottles or cells inside the camel one
by one pour their water into the stomach from day to day, whenever the
camel feels thirsty. Is not that most wonderful?

And there is yet another very wonderful thing about the camel. His
hump! It is just as wonderful whether it is one hump or two humps. I
shall tell you.

The camel's hump is his _store of food_! Yes, just as he carries his
own drinking water inside his stomach, so he also carries his own
store of food in his hump.

This is how he does it:

When the camel is quite well and strong, if he eats any food which is
a little more than he actually needs for his hunger, that food after a
while goes to his hump and helps to make it bigger. In this way the
hump becomes a store of all the extra food that he has eaten. Then, on
going on a long journey through the desert, if the camel has nothing
to eat and begins to feel hungry and weak, a little of the hump is
used up to give him strength, just as if he were to eat a meal. In
this way he can go for many days without food, but of course his hump
will get smaller and smaller.

[Illustration: Crossing the Desert with Camels]

But his master does not actually take him through the desert without
giving him _any_ food or drink; in fact he always gives the camel some
of the figs and dates which