uence of the new
spirit in biology; and among his examinees at that time there was
at least one who, knowing Huxley's writings, but his writings
only, looked forward to the _viva voce_ test, not as a trial but
as an occasion of delight. He wrote almost incessantly for all
editors who were prepared to give adequate pay to a pen able to
deal with scientific themes in a manner at once exact and
popular, incisive and correct. During this period he was
gradually passing from his first anatomical love, the structure
of the Invertebrates, to Vertebrate work, and although he
continued to take a deep interest in the course of the progress
of research in that group of animals, the publication of his
great work on oceanic hydrozoa by the Ray Society was the last
piece of important work he wrote upon any anatomical subject
apart from vertebrates. His work in connection with the
Geological Survey naturally attracted his attention most closely
to vertebrates, and, towards the close of the fifties, he was led
to make a special study of vertebrate embryology, a subject which
the investigations of Koelliker and others in Germany were
bringing into prominence. The first result of this new direction
of his enquiries was embodied in a Croonian Lecture delivered in
1858 'On the Theory of the Vertebrate Skull.' Sir Richard Owen,
who was at that time the leading vertebrate anatomist in England,
had given his support to an extremely complicated view of the
skull as being formed of a series of expanded vertebrae moulded
together. The theory was really a legacy from an old German
school of which the chief members were Goethe, the poet, and
Oken, a naturalist, who was more of a metaphysical philosopher
than of a morphologist. Huxley pointed out the futility of
attempting to regard the skull as a series of segments, and of
supporting this view by trusting to superficial resemblances and
abstract reasoning, when there was a definite method by which the
actual building up of the skull might be followed. Following the
lines laid down by Rathke, another of the great Germans from
whose investigations he was always so willing to find
corroboration and assistance in his own labours, he traced the
actual development of the skull in the individual. He shewed
that the foundat