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Show 14 CONVERSION OF THE ORANG-OUTANG [Ch. I. of species would be modified by the influence of local revolu .. tions. Now if' the first of these principles, the tendency to pro-gressiv: development, were left to exert its.elf with perfect freedom, it would give rise, says Lamarck, tn the course of ages, to a graduated scale of being, where the most insensible transition might be traced from the simplest to the most compound structure, from the humblest to the most exalted ~egrec of intelligence. But in consequence of the perpetual mter~ ference of the external causes before mentioned, this regular order is greatly interfered with, and an approximation only to such a state of things is exhibited by the animate creation, the progress of some races being retarded by unfavourable, and that of others accelerated by favourable, combinations of circumstances. Hence, all kinds of anomalies interrupt the continuity of the plan, and chasms, into which whole genera or ·families might be inserted, are seen to separate the nearest existing portions of the series. . Such is the machinery of the Lamarckian system ; but our readers will hardly, perhaps, be able to form a perfect conception of so complicated a piece of mechanism, unless we exhibit it in motion, and shew in what manner it can work out, under the author's guidance, all the extraordinary effects which we behold in the present state of the animate creation. We have only space for exhibiting a small part of the entire process by which a complete metamorphosis is achieved, and shall, there· fore, omit the mode whereby, after a countless succession of generations, a small gelatinous body is transformed into an oak or an ape. We pass on at once to the last grand step in the progressive scheme, whereby the orang-outang, having been already evolved out of a monad, is made slowly to attain the attributes and dignity of man. One of the races of quadrumanous animals which had reached the highest state of perfection, lost, by constraint of circumstances, (concerning the exact nature of which tradition is unfortunately silent,) the habit of climbing trees, and of Ch. I.) INTO TilE IJUMAN SPECIES, 15 hanging on by grasping the boughs with their feet as with hands. The individuals of this race being obliged for a long series of generations to use their feet exclusively for walking, and ceasing to employ their hands as feet, were transformed into bimanous animals, and what before wete thumbs became mere toes, no separation being required when theit· feet were used solely for walking. Having acquired a habit of holding themselves upright, their legs and feet assumed insensibly a conformation fitted to support them in an erect attitude, till at last these animals could no longer go on all fours without much inconvenience. The Angola orang, Simia troglodytes, Linn., is the most perfect of animals, much more so than the Indian orang, Bimia Safyrus, which has been called the orang-outang, although both are very inferior to man in corporeal powers and intelligence. These animals frequently hold themselves upright, but their organization has not yet been sufficiently modified to sustain them habitually in this attitude, so that the standing posture is very uneasy to them. When the Indian orang is compelled to take flight from pressing danger, he immediately falls down upon all fours. shewing clearly that this was the original position of the animal. Even in man, whose organization, in the course of a long series of generations, lms advanced so much farther, the upright posture is fatiguing and can only be supported for a limited time, and by aid of the contraction of many muscles. If the vertebral column formed the axis of the human body, and supported the head an~ ~II the other parts in equilibrium, then might the upright positiOn be a state of repose; but as the human head does not articulate in the centre of gravity; as the chest, belly, and other parts, press almost entirely forward with their whole weight, and as the vertebral column reposes upon an oblique base, a wa~chful acti~ity is required to prevent the body from falling. Children w luch have large heads and prominent bellies can hardly walk at the end even of two years, and their frequent |
