to the development
of the brain, and its inner surface gives an approximate idea of the
outer surface of the brain. In this correspondence lies the only sound
kernel of the sickly, overgrown fancies of phrenology. The various
development of the skull allows of an approximate inference as to the
various degrees of development of the brain and of the mental
faculties. The comparative study of the skulls of the vertebrate
animals had excited the lively interest of morphologists by the end of
the last century, when comparative anatomy was beginning to
constitute a special science; and the genetic inquiry as to the
morphological significance and development of the skull soon grew out
of it. It was no less a man than our greatest German poet who first
answered this question, and propounded the theory that the skull was
neither more nor less than the modified foremost end of the vertebral
column, and that the separate groups of bones which lie behind one
another in the human skull, as in that of all the higher vertebrata,
answer to the separate modified vertebrae. This "vertebral theory" of
the skull, which Von Goethe and Oken simultaneously and independently
attempted to prove, aroused universal interest and maintained its
ground for seventy years, while many attempts were made to improve and
enlarge upon it in detail.

A quite new light was thrown on this, as on every other morphological
question, as soon as Darwin in 1859 had once more put into our hands
the torch of the doctrine of descent. The inquiry as to the origin of
the skull now assumed a real and tangible form. Since all vertebrate
animals, from fishes up to man, agree so completely as to their
essential internal structure that they can be rationally conceived of
no otherwise than as branches of one stock and as descendants of one
parent-form, the distinctly formulated question as to the skull
theory which now started into prominence was this: "How, historically,
has the skull of man and of the higher animals originated from that of
the lower animals? How is the development of the bones of the skull
from the vertebrae to be proved?" The answer to these difficult
questions was supplied by the first comparative anatomist of the
present day, by Carl Gegenbaur. After Huxley had pointed out that the
ontogenesis or individual development of the skull by no means
favoured the older hypothesis of Goethe and Oken, Gegenbaur brought
forward evidence that the fundamental id