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, we get no answer; but if we ask
how he does it, we find out that he stores up food in his den, hence
must take a lunch between his naps. The woodchuck hibernates, also, but
he stores up fuel in the shape of fat in his own body. The porcupine is
above ground and active all winter. He survives by gnawing the bark of
certain trees, probably the hemlock. We have two species of native mice
that look much alike, the white-footed mouse and the jumping, or
kangaroo, mouse. The white-foot is active the season through, over and
under the snow; the jumper hibernates all winter, and apparently
accomplishes the feat by the power he has of barely keeping the spark of
life burning. His fires are banked, so to speak; his temperature is very
low, and he breathes only at long intervals.
If, then, we ask with Emerson, "_why_ Nature loves the number five," and
"_why_ the star form she repeats," we shall be put to it for an answer.
We can only say that with living things odd numbers are more likely to
prevail, and with non-living, even numbers.
Some seeds have wings and some have not. To ask why, is a blind
question, but if we ask _how_ the wingless seeds get sown, we may add to
our knowledge.
In our own practical lives, in which experimentation plays such a part,
we are often compelled to ask why this result and not that, why this
thing behaves this way and that thing that way. We are looking for
reasons or causes. The farmer asks why his planting in this field was a
failure, while it was a success in the next field, and so on. An
analysis of his soil or of his fertilizer and culture will give him the
answer.