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

INTRODUCTION

touch. For all we know there may be gladness in dancing waves and a real freshness in the sunrise itself.

So far as our knowledge goes all feeling, all consciousness, requires concurrent material changes; we do not know of feeling without material change in ourselves or in those others who tell us of their sensations. We have already hinted that the converse may also be the case, and there may be no material change without feeling. But on one point let us be clear. When we attribute feeling to an oyster or an amceba we do so because it behaves to a certain extent like ourselves, and we imagine such feeling as resembling our own to the same degree as the behaviour resembles our own. When we attribute feeling to a material change, on the other hand, we are led to do so not by sympathy but by logic. One cannot imagine any sort of intelligible emotion in a piece of zinc that is dissolving in hydrochloric acid ; one does not suspect litmus of shame because it blushes at the touch of vitriol. The idea of feeling in inorganic material processes is an almost mathematical abstraction ; it involves con-

siderable extension of the usual meaning

of the word “feeling.” ‘This point will be clearer when we have dealt with the texture and structure of living substance, and particularly of brains, sense-organs, and nervous tissue. We will study them and their behaviour as far as we can before we bring feeling into our discussion. But we note this internal aspect of life here merely to explain that for a time it will be convenient to disregard it and view living things from an entirely external standpoint. When we have built up a coherent picture of the forms and behaviour of life as they appear outside ourselves we shall be in a securer position for the correlation of that visible world with the far more mysterious world, outside the frame of time and space, which sees and knows.

§ 6 A Preliminary View of Living Forms

Let us now consider how life in general as an external phenomenon presents itself to an ordinary intelligent human being who has had no special instruction in biology. In response to the question, what were the chief sorts of life, such a person would probably answer, plants and animals, and explain that plants were green-coloured in whole or in part, were rooted to one place and fed chiefly upon non-living matter

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derived from the atmosphere and the soil, while animals moved about freely and needed to feed upon the substance of other living things. There would probably be a difficulty about sponges and one or two other such things—sea-anemones, for example, and sea-mats—whether they were plants or animals, and an exception to the general greenness of plants would have to be made in the case of fungi. Further questioning would elicit further difficulties in maintaining the distinction of plants from animals, which had at first seemed so plain and clear. It had seemed all right on land amid familiar surroundings, but as odd corners of the world, beaches, and rock-pools, dark shadows and festering corners of decay in forests, were explored, the first easy assumptions would have to be modified.

Moreover, if the question of what sorts there are of animals were next taken up, there would perhaps come the traditional answer of “Birds, Beasts, and Fishes.” Are men animals? A question much debated. And are these three classes inclusive? Some further sorts of animals would be named. Insects would be noted, worms, “creeping things”? such as spiders, lice, and so forth. The “so forth’? would be found to be a rather expanding and varied division. “‘Fishes” also would have to be stretched beyond its original intention when one thought of lobsters, starfish, and oysters. And what was a frog or a crocodile? A “beast,” perhaps, but lacking the familiar protection of hair or feathers, and with no warmth of blood. To the ordinary man living a commonplace life in a town or in the countryside, the birds, beasts, and finny fishes would still seem to be so largely the bulk of life, that it would be a strange and difficult thing to hear that life had been active and varied for millions of years before ever a bird or a beast or a leafy tree or a flower existed. They are the living setting of our world now, they are an essential familiar part of our existence as those others are not. Our race has built its mind, its fears, panics, fables, and beliefs on fur and feather and fin, and it is hard to think of a whole world of animated existence without them. From them we go to the stranger creatures and to them we return, as one returns to one’s home from unfamiliar places.

Aristotle we may take as standing in this matter on the dividing line between the unsystematic intelligent person and _ the systematic inquirer. He was one of the earliest men to become systematic. He left no complete classification of animals, but he