When Huxley made his first discoveries, entirely different ideas prevailed.  The animal kingdom was supposed to offer a series of types, of moulds, into which the Creator at the beginning of the world had cast the substance of life.  These types were independent of each other, and had been so since the beginning of things.  Anatomists were concerned chiefly with systematic work, with detecting and recording the slight differences that existed among the numbers of animals grouped around each type.  No attempt was made to see connection between type and type, for where these had been separately created there was nothing to connect them except possibly some idea in the mind of the Creator.  This apparently barren attitude to nature was stronger in men’s minds because it had inspired the colossal achievements of Cuvier, a genius who, under whatever misconceptions he had worked, would have added greatly to knowledge.  As we have seen in the first chapter, Huxley, through Wharton Jones, and through his own reading, had been brought under the more modern German thought of Johannes Mueller and Von Baer.  He had learned to study the problems of living nature in the spirit of a physicist making investigations into dead nature.  In the anatomy of animals, as in the structure of rocks and crystals, there were to be sought out “laws of growth” and shaping and moulding influences which accounted for the form of the structures.  To use the technical term, he was a morphologist:  one who studied the architecture of animals not merely in a spirit of admiring wonder, but with the definite idea of finding out the guiding principles which had determined these shapes.

Not only was the prevailing method of investigation faulty, but actual knowledge of a large part of the animal kingdom was extremely limited.  In the minds of most zooelogists the animal kingdom was divided into two great groups:  the vertebrates and invertebrates.  The vertebrate, or back-boned, animals were well known; comparatively speaking they are all built upon the type of man; and human anatomists, who indeed made up the greater number of all anatomists, using their exact knowledge of the human body, had studied many other vertebrates with minute care, and, from man to fishes, had arranged living vertebrates very much in the modern order.  But the invertebrates were a vague and ill-assorted heap of animals.  It was not recognised that among them there were many series of different grades of ascending complexity, and there was no well-known form to serve as a standard of comparison for all the others in the fashion that the body of man served as a standard of comparison for all vertebrates.  Here and there, a few salient types such as insects and snails had been picked out, but knowledge of them helped but little with a great many of the invertebrates.  The great Linnaeus had divided the animal kingdom into four groups of vertebrates:  mammals, birds, reptiles, and fishes, but for the invertebrates he had done no more than