tion inclined obliquely upwards
and forwards, just as in the next three diagrams, which represent the
skeletons of an Orang, a Chimpanzee, a Gorilla, and you find you have no
trouble in identifying the bones throughout; and lastly turn to the end
of the series, the diagram representing a man's skeleton, and still you
find no great structural feature essentially altered. There are the
same bones in the same relations. From the Horse we pass on and on, with
gradual steps, until we arrive at last at the highest known forms. On
the other hand, take the other line of diagrams, and pass from the Horse
downwards in the scale to this fish; and still, though the modifications
are vastly greater, the essential framework of the organization remains
unchanged. Here, for instance, is a Porpoise: here is its strong
backbone, with the cavity running through it, which contains the spinal
cord; here are the ribs, here the shoulder blade; here is the little
short upper-arm bone, here are the two forearm bones, the wrist-bone,
and the finger-bones.

Strange, is it not, that the Porpoise should have in this queer-looking
affair--its flapper (as it is called), the same fundamental elements as
the fore-leg of the Horse or the Dog, or the Ape or Man; and here you
will notice a very curious thing,--the hinder limbs are absent. Now,
let us make another jump. Let us go to the Codfish: here you see is the
forearm, in this large pectoral fin--carrying your mind's eye onward
from the flapper of the Porpoise. And here you have the hinder limbs
restored in the shape of these ventral fins. If I were to make a
transverse section of this, I should find just the same organs that
we have before noticed. So that, you see, there comes out this strange
conclusion as the result of our investigations, that the Horse, when
examined and compared with other animals, is found by no means to
stand alone in nature; but that there are an enormous number of other
creatures which have backbones, ribs, and legs, and other parts arranged
in the same general manner, and in all their formation exhibiting the
same broad peculiarities.

I am sure that you cannot have followed me even in this extremely
elementary exposition of the structural relations of animals, without
seeing what I have been driving at all through, which is, to show you
that, step by step, naturalists have come to the idea of a unity of
plan, or conformity of construction, among animals which appeared at