ds, although the
pigment was actually lighter on the under side, it was so much less
intensely illuminated, that the result was the same in tint as the
other side under the clear sharp light of the sky.

Many a person, looking down into the water from a bridge, sees nothing
whatever of the fish in the water below, because their backs are
exactly like the bottom of the stream. Suddenly one of the fish, by a
quick movement, turns its lighter under side over in such a way that
it is clearly illuminated from the sky. Immediately a flash as of
silver strikes the eye of the onlooker and makes him aware of the
presence of the fish which had previously been undetected. If rendered
thus suspicious, the observer will carefully examine the bottom of the
water, he may quite likely find dozens of fish which had previously
escaped his attention.

Nature is very versatile. So many of her apparently chance ventures
have proved successful that she has retained many devices by which her
children may be safe. One of these, which is doubtless often quite
effective and may serve to save an animal's life, is that of being
able to emit an odor so nauseating as to offend the enemy's sense of
smell, and doubtless remove the keen edge of his appetite. It is not
uncommon among the group of insects properly known as bugs to possess
an exceedingly unpleasant odor. Anyone who has handled a squash bug
will know exactly what I mean, and there are other members of the
group not so common as the squash bug, which, at least to the human
nose, are distinctly offensive. Some of the beetles also save
themselves by this device.

One of the most interesting developments of this peculiarity is found
in the case of the common skunk. This creature has in each groin a
gland capable of secreting a highly offensive fluid. Ordinarily this
liquid is kept safely within its sac, and for a long time none of it
may escape. When closely cornered, the skunk will turn its tail toward
the enemy and with a quiver and a flip of his tail it can guide the
openings of two little tubes that come out along the root of the tail
in such fashion as to eject the fluid in a fine and foul-smelling
stream against the animal from which the skunk would escape. Once
fairly hit by this fluid, I imagine most animals will drop the skunk.
A dog surely will, and will hate himself for having made the attempt
to capture anything which must be so ignominiously allowed to escape.
If ones clothing