substantial
nest, through which even the air will not chill the eggs enough to
prevent their hatching, while the warmth is supplied by the mother's
body. It is often a matter of surprise to many people that a bird
should contrive to build a nest so exquisitely circular. The trick,
after all, is not quite so difficult as it looks. The robin gathers up
a few sticks and places them as the beginning of the platform. More
and more are brought and woven into each other, making a framework
altogether too big for the nest. Then mud is brought and plastered
inside of this. With the plastering of this mud the careful
circularity of the work begins. Every time a little material has been
added the robin sits down in the nest and revolves her body, in this
way shaping the interior much as the potter shapes a pot. In the case
of the artisan, it is the pot that revolves. In the case of the robin,
the bird itself revolves. The effect is the same in both cases--a
circular vessel is produced. A little lining added to the interior of
the nest softens it for the reception of the eggs. In this exquisite
home the robin lays her eggs, and sits upon them until they are
developed enough to hatch, and then feeds the young until they are old
enough to feed themselves.

Far more remarkable than any of the devices thus far described are the
wonderful developments which have come in the class of animals known
as the mammals. Here the most wonderful protection is made for the
care and feeding of the young. But this is to be the subject of a
separate chapter.

As long as we thought of each sort of animal as being a separate
species shaped in the beginning by the hands of the Creator, each of
these devices seemed to us a new manifestation of the Divine
Providence, whose fertile planning had conceived so many methods of
providing for his children. Unconsciously we thought of God acting as
man acted. Each animal seemed a purely separate invention purposely
designed for an especial place. Now we understand the plan in creation
better, and see that each animal has come from another not quite like
itself, some distance back, and this from still another. Our
admiration for these devices as they arise through evolution is no
less, but takes on another form.

CHAPTER VI

LIFE IN THE PAST

Anyone who earnestly studies plants and animals as they exist in the
world to-day cannot help wondering how the earth began and where it
got its life. This i