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 foundations of the skull and of the backbone were laid down in a fashion quite different, and that it was impossible to regard both skull and backbone as modifications of a common type laid down right along the axis of the body.  The spinal column and the skull start from the same primitive condition, whence they immediately begin to diverge.  It may be true to say that there is a primitive identity of structure between the spinal or vertebral column and the skull; but it is no more true that the adult skull is a modified vertebral column than it would be to affirm that the vertebral column is a modified skull.”

Since this famous lecture, a number of distinguished anatomists have studied the development of the skull more fully; but they have not departed from the methods of investigation laid down by Huxley, and their conclusions have differed only in greater elaboration of detail from the broad lines laid down by him.  Apart from its direct scientific value, this lecture was of importance as marking the place to which Huxley had attained in the scientific world.  Two years later, it is true, the London Times, referring to a famous debate at a meeting of the British Association at Oxford, spoke of him as “a Mr. Huxley”; but in the scientific world he was accepted as the leader of the younger anatomists, and as one at least capable of rivalling Owen, who was then at the height of his fame.  The Croonian Lecture was in a sense a deliberate challenge to Owen, and in these days before Darwin, to challenge Owen was to claim equality with the greatest name in anatomical science.