naturalists. Yet believing, as I do, that classification,
rightly understood, means simply the creative plan of God as expressed
in organic forms, I feel the importance of attempting at least to
present it in a popular guise, divested, as far as possible, of
technicalities, while I would ask the indulgence of my readers for such
scientific terms and details as cannot well be dispensed with, begging
them to remember that a long and tedious road may bring us suddenly upon
a glorious prospect, and that a clearer mental atmosphere and a new
intellectual sensation may well reward us for a little weariness in the
outset. Besides, the time has come when scientific truth must cease to
be the property of the few, when it must be woven into the common life
of the world; for we have reached the point where the results of science
touch the very problem of existence, and all men listen for the solving
of that mystery. When it will come, and how, none can say; but this much
at least is certain, that all our researches are leading up to that
question, and mankind will never rest till it is answered. If, then, the
results of science are of such general interest for the human race, if
they are gradually interpreting the purposes of the Deity in creation,
and the relation of man to all the past, then it is well that all
should share in its teachings, and that it should not be kept, like the
learning of the Egyptians, for an exclusive priesthood who may expound
the oracle according to their own theories, but should make a part of
all our intellectual culture and of our common educational systems. With
this view, I will endeavor to simplify as far as may be my illustrations
of the different groups of the Animal Kingdom, beginning with a more
careful analysis of those structural features on which classes are
founded.

I have said that the Radiates are the lowest type among animals,
embodying, under an infinite variety of forms, that plan in which all
parts bear definite relations to a vertical central axis. The three
classes of Radiates are distinguished from each other by three distinct
ways of executing that plan. I dwell upon this point; for we shall never
arrive at a clear understanding of the different significance and value
of the various divisions of the Animal Kingdom, till we appreciate the
distinction between the structural conception and the material means by
which it is expressed. A comparison will, perhaps, better explain my
me