attach themselves to floating pieces of timber, and in the crabs, lobsters, and shrimps of our shores. The very best accounts we have, of the structure, habits, and economy of the lower tribes of animals, have been furnished to us by individuals who did not think it beneath them to devote many years to the study of a single species; and as there are very few which have been thus fully investigated, there is ample opportunity for every one to suit his own taste in the choice of an object. And none but those who have tried the experiment, can form an estimate of the pleasure which the study of Nature is capable of affording to its votaries. There is a simple pleasure in the acquisition of knowledge, worth to many far more than the acquisition of wealth. There is a pleasure in looking in upon its growing stores, and watching the expansion of the mind which embraces it, far above that which the miser feels in the grovelling contemplation of his hard-sought pelf. There is a pleasure in making it useful to others, comparable at least to that which the man of generous benevolence feels in ministering to their relief with his purse or his sympathy. There is a pleasure in the contemplation of beauty and harmony, wherever presented to us. And are not all these pleasures increased, when we are made aware,-as in the study of Nature we soon become,-that the sources of them are never-ending, and that our enjoyment of them becomes more intense in proportion to the comprehensiveness of our knowledge? And does not the feeling that we are not looking upon the inventions or contrivances of a skilful human artificer, but studying the wonders of a Creative Design infinitely more skilful, immeasurably heighten all these sources of gratification? If it is not every one who can feel all these motives, cannot every one feel the force of some? There is certainly no science which more constantly and forcibly brings before the mind the power, the wisdom, and the goodness of the Creator. For whilst the Astronomer has to seek for the proofs of these attributes in the motions and adjustments of a universe, whose nearest member is at a distance which imagination can scarcely realize, the Physiologist finds them in the meanest worm that we tread beneath our feet, or in the humblest zoophyte dashed by the waves upon our shores, no less than in the gigantic whale, or massive elephant. And the wonderful diversity which exists amongst the several tribes of animals, presents us with a continual variety in the mode in which these adjustments are made, that prevents us from ever growing weary in the search. But it is not only in affording us such interesting objects of regular study, that the bounty of Nature is exhibited. Perhaps it is even more keenly felt by the mind which, harassed by the cares of the world, or vexed by its disappointments, or fatigued by severer studies, seeks refuge in her calm retirement, and allows her sober gladness to exert its cheering and tranquillizing influence on the spirit. "With tender ministrations, thou, O Nature, COLERIDGE DISTINCTIVE CHARACTERS OF ORGANIZED BODIES. 17 CHAPTER I. OF THE VITAL OPERATIONS OF ANIMALS, AND THE INSTRUMENTS BY WHICH THEY ARE PERFORMED. 1. LIVING beings, whether belonging to the Animal or to the Vegetable kingdom, are distinguished from the masses of inert matter of which the Mineral kingdom is made up, by peculiarities of form and size, of structure, of elementary composition, and of actions.—Wherever a definite form is exhibited by Mineral substances, it is bounded by plane surfaces, straight lines, and angles, and is the effect of the process of crystallization, in which particles of like nature arrange themselves on a determinate plan, so as to produce a regular aggregation; and there is, probably, no Inorganic element or combination which is not capable of assuming such a form, if placed in circumstances adapted to the manifestation of its tendency to do so. The number of different crystalline forms is by no means large; and as many substances crystallize in several dissimilar forms, whilst crystals resembling one another in form often have a great diversity of composition, there is no constant correspondence between the crystalline forms and the essential nature of the greater number of mineral substances. If that peculiar arrangement of the molecules which constitutes crystallization should be wanting, so that simple cohesive attraction is exercised in bringing them together, without any general control over their direction, an indefinite or shapeless figure is the result. With this indefiniteness of form, there is an absence of any limit whatever in regard to size: a crystal may go on increasing continuously, so long as there is new material supplied; but this new material is deposited upon its surface merely, and its addition involves no interstitial change; the older particles, which were first deposited, and which continue to form the nucleus of the crystal, remaining just as they were. In Organized bodies, on the other hand, we meet with convex surfaces and rounded outlines, and with a general absence of angularity; and the simplest grades, both of Animal and of 18 DISTINCTIVE CHARACTERS OF ORGANIZED BODIES. Vegetable life, present themselves under a shape which approaches more or less closely to the globular. From the highest to the lowest, each species has a certain characteristic form, by which it is distinguished; this form, however, often presents marked diversities at different periods of life, and it is also liable to vary within certain limits among the individuals of which the species is composed. The size of Organized structures, like their form, is restrained within tolerably definite limits, which may nevertheless vary to a certain extent among the individuals of the same species. These limits are most obvious in the higher animals, whilst they seem almost to disappear among certain members both of the Animal and the Vegetable kingdoms, which tend to increase themselves almost indefinitely by a process of gemmation or budding, so as to produce aggregations of enormous size. Such aggregations, however, being formed by the repetition of similar parts, which can maintain their existence when detached from one another, may, in some sense, be regarded as clusters of distinct organisms, rather than as single individuals. Such is the case, for example, with the wide-spreading forest-tree, and with those enormous masses of coral of which reefs and islands are composed in the Polynesian Archipelago. For every separate leaf-bud of the tree, like every single polype of the coral, if detached from its stock, can, under favourable circumstances, perform all the functions of life, and can develop itself into a new fabric resembling that from which it was separated. 2. The differences between Organized and Inorganic bodies, in regard to their structure, are much more important than those which relate to their external configuration.. Every particle of a mineral substance, in which there has not been a mere mixture of components, exhibits the same properties as those possessed by the whole; the minutest atom of carbonate of lime, for instance, has all the properties of a crystal of calc-spar, were it as large as a mountain. Hence it is the essential nature of an Inorganic body that each of its particles possesses a separate individuality, and has no relation but that of juxtaposition to the other particles associated with itself in one mass.-The Organized structure, on the other hand, receives its designation from being made up of a greater. or less number of dissimilar parts or organs; each of these DISTINCTIVE CHARACTERS OF ORGANIZED BODIES. 19 being the instrument of some special action or function, which it performs under certain conditions; and the concurrence of all these actions being necessary to the maintenance of the structure in its normal or regular state. Hence there is a relation of mutual dependence among the parts of an Organized fabric, which is quite distinct from that of mere proximity; and this relation is most intimate, not in the case of those beings which have the greatest multiplication of parts, but among those in which there is the greatest dissimilarity among the actions of the several organs. Thus it has been just shown that among Plants and Zoophytes, a small fraction of an organism may live independently of the rest; the necessary condition being that it shall either itself contain all the organs essential to life, or shall be capable of producing them, as when the leaf-bud develops rootlets for its nutrition. This "vegetative repetition," and consequent capacity of sustaining the loss of large portions of the fabric, still shows itself in animals much higher in the scale than Zoophytes; thus it is not uncommon to meet with Star-fish in which not only one or two, out of the five similar arms, but even three or four, have been lost, without the destruction of the animal's life; and this is the more remarkable, as these arms are not simply members for locomotion or prehension, but are really divisions of the body, containing prolongations of the stomach. In like manner, many of the Worm tribes, whose bodies show a longitudinal repetition of similar parts, can lose a large number of their joints without sustaining any considerable damage. In the bodies of the higher animals, however, where there are few or no such repetitions (save in the two lateral halves of the body), and where there is, consequently, a greater diversity in character and function. between the different organs, the mutual dependence of their actions upon one another is much more intimate, and the loss of a single part is much more likely to endanger the existence of the whole. Such structures are said to be more highly organized than those of the lower classes; the principle of "division of labour" being carried much further in them, a much greater variety of objects being attained, and a much higher perfection in the accomplishment of them being thus provided for. Thus the individuality of a plant or a zoophyte may be said to reside in each of its multiplied parts; |