l Society-Old and New Ideas of the Animal Kingdom-What Huxley Dis

ing in incredible numbers, and, like the green vegetation of the earth, forming the ultimate food-supply of all the living things around them. Innumerable animals, great and small, live on the plants or upon their fellows, and, however far he may be from land, the naturalist has always abundant material got by his daily use of the tow-net. This drifting population floats at the mercy of the waves. Most of the animals are delicate, transparent creatures, their transparency helping to protect them from the attacks of hungry fellows. Nerves, muscles, skin, and the organs generally are clear, pale, and hardly visible. Such structures as the liver, the reproductive organs, and the stomach, which cannot easily become transparent, are grouped together into small knots, coloured brown like little masses of sea-weed. Other floating creatures are vividly coloured, but the hues are bright blues and greens closely similar to the sparkling tints of sea-water in sunlight. The different members of this marine flotsam frequently rise and fall periodically: some of them sinking by day to escape the light, others rising only by day; others, again, appearing on the surface in spring, keeping deep down in winter.

ing all the information I required. The great matter is to obtain a good successive supply of specimens, as

s spent in libraries and museums, comparing his own observations with the recorded observations of earlier workers, and receiving from the combination of his own work and the work of others new ideas for his future investigations. It was all e

and in 1849 I drew up a more elaborate paper and forwarded it to the Royal Society. This was my dove, if I had only known it; but owing to the movements of the ship I heard nothing of that either until my return to England in the latter end of the year 1850, when I fo

t officer's father, the Bishop of Norwich, who communicated it to the Royal Society. It is a curious circumstance that Huxley, who afterwards met with

ope lashed to secure steadiness, cramped within a tiny cabin, jostled by the tumult of a crowded ship's life, with the scantiest supply of books of reference, with no one at hand of whom he could take counsel on the problems opening up before him, he gathered for himself during these four years a large

th men so illustrious as Joule, the discoverer of the relation between force and heat, Stokes, the great investigator of optical physics, and Humboldt, the t

second paper, on the anatomy of Salpa and Pyrosoma, the phenomena have received the most ingenious and elaborate elucidations, and have given rise to a process of reasoning, the

nce. A large number of later investigators have advanced upon the lines he laid down; and just as the superstructures of a great building conceal the foundations, so later anatomical work, although it has only amplified and extended Huxley's discoveries, has made them seem less striking to the modern reader. The present writer, for instance, learned all that he knows of anatomy in the last ten years, and until he turned to it for the purpose of this volume he had never referred to Huxley's ori

et, the tops of the twigs; and it is by examination of the structure of this surface that we reconstruct in imagination the whole system of branches, and know that certain twigs, from their likeness, meet each other a little way down; that others are connected only very deep down, and that others, again, spring free almost from the beginning. The fossils of beds of rock of different geological ages give us incomplete views of the surface of the thicket of life, as it was in earlier times. These views we have of the past aspects of the animal kingdom are always much more incomplete than our knowledge of the existing aspect; partly because

ype, 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

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 Linn?us 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 to pick out the insects as one group and to call everything else "Vermes" or worms. The insects included all creatures possessed of an external skeleton or hard skin divided into jointed segments, and included forms so different as insects, spiders, crabs, and lobsters. But Vermes included all the members of the animal kingdom that were neither vertebrates nor insects. Cuvier advanced a little. He got rid of the comprehensive title Vermes-the label of the rubbish-heap of zo?logists. He divided animals into four great subkingdoms: Vertebrates, Mollusca, Articulata, Radiata. These names, however, only covered very superficial resemblances among the animals designated by them. The word Mollusca on

oubt simply because they were among the most abundant of the animals that could be obtained from the ship. He made endless dissections and drawings, and, ab

on the part of the observers, but rather because they have contented themselves with stating matters of detail concerning particular genera and species, in

the complicated systems of canals and organs were composed of two "foundation-membranes," two thin webs of cells, one of which formed the outermost layer of the body, while the inner formed the lining of the stomach and canals in the thinner parts of the body, such as the edges of the umbrella-like disc, and towards the ends of the tentacles. These thin webs formed practically all the body. In the thicker parts there was interposed between them an almost structur

variously shaped cavity inasmuch as all its organs were so composed. The generative organs were external, being variously developed processes of the two membranes. The pecu

all nutritive branches, each ending in a mouth surrounded by a circle of waving tentacles armed with batteries of thread-cells, while another set of hanging protrusions bear the grape-like reproductive organs. On the upper surface of the bladder is fixed a purple sail of the most brilliant colour, by which the floating creature is blown through the water. When the weather is rough, the bladder empties, and the creature sinks down into the quiet water below the waves, to rise again when the storm is over. This, and its equally wonderful allies, Huxley showed to be a complicated colony of hydra-like creatures, each part being composed of two membranes, and therefore essentially similar to Medus?. Thus, by a great piece of constructive work, an assemblage of animals was gathered into a new group and shewn to be organised upon one simple and uniform plan, and, even in the most complex and aberrant forms, reducible to the same type. The group, and Huxley's conception of its structure, are now absolutely accepted by anatomists, and have made one of the corner-stones of our modern idea of the arrangement of the animal kingdom. With the exception of sponges, concerning the exact relations of which there is still dispute, and of a few sets of parasitic and possibly degenerate creatures, all animals, the bodies of which are multicellular, from the simple fresh-water hydra up to man, are divided into two great groups. The structure of the simpler of these groups is exactly what Huxley

ll the ideas in this first memoir by Huxley. In the course of d

as do the serous and mucous layers of the germ: the outer becoming developed into the muscular system, and giving rise to the organs of

on to be swamped by preconceived ideas. At the time he did no more than to make the comparison. It was much later that the full importance of it became known, when more extended work on the embryology of vertebrates and of the different groups of the invertebrates had made it plain that the two foundation-membranes of Huxley occur in all animals from the Medus? up to man. In the group of C?lenterata the organisation remains throughout life as nothing more than a folding in and folding out of these membranes. The early stages of all the higher animals similarly consist of complications of the two membranes; but later on there is added to them a third membrane. Thus the group that Huxley gathered together comprises those animals that as adults remain in a condition of development which is passed through in the embryonic life of all higher animals. The immense importance of this conclusion becomes p

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