are in lobes usually have
three or five lobes. But the stems of the mints are four-square, and the
cells of the honey bee are six-sided. We have five fingers and five
toes, though only four limbs. Locomotion is mechanical and even numbers
serve better than odd. Hence the six-legged insects. In the inorganic
world things attain a stable equilibrium, but in the living world the
equilibrium is never stable. Things are not stereotyped, hence the
danger of dogmatizing about living things. Growing Nature will not be
driven into a corner.

Well may Emerson ask--

Why Nature loves the number five,
And why the star form she repeats?

The number five rules in all the largest floral families, as in the
crowfoot family, the rose family (which embraces all our fruit trees),
the geranium family, the flax family, the campanula family, the
convolvulus family, the nightshade family. Then there is a large number
of flowers the parts of which go in threes, one of the best known of
which is the trillium. In animal life the starfish is the only form I
recall based on the number five.

IV. WHY AND HOW

One may always expect in living nature variations and modifications. It
is useless to ask why. Nature is silent when interrogated in this way.
Ask her how, and you get some results. If we ask, for instance, why the
sting of the honey bee is barbed, and those of the hornet and wasp and
bumble-bee, and of other wild bees, are smooth like a needle, so that
they can sting and sting again, and live to sting another day, while the
honey bee stings once at the cost of its life; or why only one species
of fish can fly; or why one kind of eel has a powerful electric
battery; or why the porcupine has an armor of quills while his brother
rodent the woodchuck has only fur and hair, and so on--we make no
addition to our knowledge.

But if we ask, for instance, how so timid and defenseless an animal as
the rabbit manages to survive and multiply, we extend our knowledge of
natural history. The rabbit prospers by reason of its wakefulness--by
never closing its eyes--and by its speed; also by making its home where
it can command all approaches, and so flee in any direction. Or if we
ask how our ruffed grouse survives and prospers in a climate where its
cousin the quail perishes, we learn that it eats the buds of certain
trees, while the quail is a ground-feeder and is often cut off by a deep
fall of snow.

If we ask why the chipmunk hibernates,