in their number and perfection under the influence of natural
selection, just as the succession of fossils actually discloses it to
us.

Comparative anatomy furnishes a second series of facts which are of
great importance for the forming of our inductive law. This branch of
morphology compares the adult structures of living things, and seeks
in the great variety of organic forms the stable and simple law of
organisation, or the common type or structure. Since Cuvier founded
this science at the beginning of the nineteenth century it has been a
favourite study of the most distinguished scientists. Even before
Cuvier's time Goethe had been greatly stimulated by it, and induced to
take up the study of morphology. Comparative osteology, or the
philosophic study and comparison of the bony skeleton of the
vertebrates--one of its most interesting sections--especially
fascinated him, and led him to form the theory of the skull which I
mentioned before. Comparative anatomy shows that the internal
structure of the animals of each stem and the plants of each class is
the same in its essential features, however much they differ in
external appearance. Thus man has so great a resemblance in the chief
features of his internal organisation to the other mammals that no
comparative anatomist has ever doubted that he belongs to this class.
The whole internal structure of the human body, the arrangement of its
various systems of organs, the distribution of the bones, muscles,
blood-vessels, etc., and the whole structure of these organs in the
larger and the finer scale, agree so closely with those of the other
mammals (such as the apes, rodents, ungulates, cetacea, marsupials,
etc.) that their external differences are of no account whatever. We
learn further from comparative anatomy that the chief features of
animal structure are so similar in the various classes (fifty to sixty