guished from his parents.

There is a common belief that at a certain time the tail of the tadpole
falls off. Nature is not so wasteful. This tail, when it has served its
purpose as a swimming organ--that is to say, as soon as the hind legs
have developed enough to take up their duties--is gradually absorbed.

And this fact recalls another. It will be remembered that it was pointed
out that for some time after leaving the egg no food was taken at the
mouth, because there was no mouth, but life was sustained by the reserve
of yolk within the body, the remains of the egg, in short. Similarly, we
have a second period when no food is taken, and this takes place while
the tail is being used up, and the mouth is being transformed. Exactly
how this using-up process is effected cannot be easily explained here;
but it forms what is known as a reserve store of food. In a similar way,
dormice, squirrels, and bears grow very fat before they retire to some
snug hole to sleep out the long winter. The gradual waste of the body
which goes on during the long sleep is made good by slowly using up the
fat which was accumulated during the summer and autumn.

At last, then, the tail of the tadpole disappears, and with this several
new features become apparent. These are the new breathing arrangements,
a new mouth and system of catching food, and shorter intestines.

[Illustration: Common Frog, showing tongue in action.]

About this new breathing. In ourselves this is done by means of our
ribs, which alternately rise, increasing the cavity of the chest and the
capacity of the lungs, and fall, or rather are pulled down, decreasing
the chest cavity, and pressing out the air from the lungs. The frog
pumps in air by that curious movement of the throat which the ignorant
suppose to be a preparation for poison-spitting. When the throat is
depressed the mouth cavity is increased, and air rushes in through the
nostrils and fills the chamber. When the floor of his mouth is raised
again the cavity is reduced, and the air is forced down the windpipe
into the lungs, being unable to escape through the nostrils, because
they are closed by special valves.

The mouth is now toothless, and of great size. The young frog feeds on
living prey, which is generally caught by the tongue. For this purpose,
the tongue in the frog and toad is fixed to the front of the floor of
the mouth, so that the tip of the tongue points _backwards_ towards the
throat! In capt