The science of life : fully illustrated in tone and line and including many diagrams

seems to have divided them into those with red blood and those without. The former he subdivided into (1) Mammals (beasts), who bring forth their young alive, into which class he put men; (2) Birds; (3) Fourfooted or creeping things (reptiles and amphibia) which lay eggs; and (4) Fishes. The animals without red blood he referred to (1) a soft-bodied group, in which he put the octopus and squid ; (2) a “ soft-shelled ”’ division of lobsters, crabs, shrimps, and such like, with jointed bodies and limbs; (3) insects, with which he included spiders and scorpions ; (4) creatures with hard, protective outer shells like the snail, murex, oyster, and sea urchins; and (5) zoophytes or plant-animals like sponges and _ seaanemones. Later we shall give a contemporary classification which has replaced this preliminary survey of living forms.

What we find as we study the history of animal classification down to the present day is a very slight variation of the original classification of the more familiar animals and a steady increase of classes and distinctions among odd and less familiar forms. The naturalist kept opening up new departments with a sort of reluctance, as odd, intractable, unclassifiable riddles were forced upon his attention. Always until quite recent times in every classification there would be a kind of ragbag class, ‘‘ Vermes,” “ Radiata,” or “‘ Zoophyta,” into which all the residue of “ puzzles”? would be thrust. First came a fine array of kindred species, varying agreeably round some well-known central form, hundreds of bird species and hundreds of fish species, clearly named and brightly depicted, and then at the end a deprecatory jumble and muddle of nonconformists. The systematic botanist kept a similar dump. He made a lovely classification of flowering plants, he never tired of arranging them and then hurled all the awkward cases together into a division of “ Cryptograms”’? which had nothing in common except that they had no flowers to be dried and put neatly between sheets of blotting paper. It is among these queer, out-of-the-way, low-caste flowers and plants, as we shall see, that some of the most interesting and illuminating work of modern tumes has been done.

From the green scum on a dank garden path to Solomon in all his glory, from the tree to the tiger, from the swarming millions of germs in a poisoned finger to the tame elephant in the Zoological Gardens, from intestinal worm to rosebud, and from lichen to whale, life plays in endless variations that

INTRODUCTION

drama of movement, metabolism, and reproduction which marks it off from the mineral kingdom and from all the interplay of inanimate Nature. And, perhaps, in endless variations it plays also upon the themes of conscious and subconscious life, it dreams and slumbers in the plant or in the motionless fish, or drinks deep of contentment or flashes into frenzies of desire and delight and terror in hunter and hunted, in basking snake or playing cub or singing bird. And the writing and reading of this book and the thought-process behind these things are life also. All these aspects must receive our attention in the general review of current biological knowledge we are now undertaking.

§ 7 The Progress of Biological Knowledge

Biology, the science of life, was practical before it became systematic. Man was a biologist perforce long before the dawn of history, classifying plants into edible and inedible, and accumulating a lore of the animals he hunted, and perhaps of the animals that hunted him. In the Old Stone Age, perhaps twenty thousand years ago, he was already making very competent drawings of the beasts that concerned him.

The Neolithic Age must have been a time of active biological enterprise. In a few thousand years man carried out a very large amount of experimental work, he domesticated and tamed nearly every animal that has ever been tamed or domesticated, and he began deliberate breeding. Mythology hints at a disposition to attempt the most extraordinary hybridisations. Every conceivable combination of domesticated species was probably attempted by Neolithic man.

The vigorous days of the Greek republics and the Hellenic empire of Alexander saw the dawn of modern science. It was a period of immense curiosity, which declined only as the dark shadow of Roman Imperialism fell upon the Mediterranean world. ‘There was an organized search for facts by Aristotle's agents under the patronage of Alexander. The first museum was, as the name implies, dedicated religiously to the Muses, and the earlier collections of curiosities were 1n temples. Hanno, the Carthaginian, after his memorable coasting voyage about Africa, hung the skins of his gorillas in a temple with an inscribed record.

Hellenic science during its phase of energy achieved some remarkable things. We hear,

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