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Page:Popular Science Monthly Volume 44.djvu/27

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surface of the soil, rapidly increases in size, and at the same time undergoes a series of metamorphoses which do not excite our wonder as much as those which meet us in legendary history, merely because they are to be seen every day, and all day long.

By insensible steps the plant builds itself up into a large and various fabric of root, stem, leaves, flowers, and fruit, every one molded, within and without, in accordance with an extremely complex, but at the same time minutely defined, pattern. In each of these complicated structures, as in their smallest constituents, there is an immanent energy which, in harmony with that resident in all the others, incessantly works toward the maintenance of the whole and the efficient performance of the part which it has to play in the economy of Nature. But no sooner has the edifice, reared with such exact elaboration, attained completeness than it begins to crumble. By degrees the plant withers and disappears from view, leaving behind more or fewer apparently inert and simple bodies, just like the bean from which it sprang, and, like it, endowed with the potentiality of giving rise to a similar cycle of manifestations.

Neither the poetic nor the scientific imagination is put to much strain in the search after analogies with this process of going forth and, as it were, returning to the starting point. It may be likened to the ascent and descent of a slung stone, or to the course of an arrow along its trajectory. Or we may say that the living energy takes first an upward and then a downward road. Or it may seem preferable to compare the expansion of the germ into the full-grown plant to the unfolding of a fan, or to the rolling forth and widening of a stream, and thus arrive at the conception of "development," or "evolution." Here, as elsewhere, names are "noise and smoke"; the important point is to have a clear and adequate conception of the fact signified by a name. And in this case the fact is the Sisyphæan process, in the course of which the living and growing plant passes from the relative simplicity and latent potentiality of the seed to the full epiphany of a highly differentiated type, thence to fall back to simplicity and potentiality.

The value of a strong intellectual grasp of the nature of this process lies in the circumstance that what is true of the bean is true of living things in general. From very low forms up to the highest—in the animal no less than in the vegetable kingdom—the process of life presents the same appearance[1] of cyclical evo-

  1. I have been careful to speak of the "appearance" of cyclical evolution presented by living things; for, on critical examination, it will be found that the course of vegetable and of animal life is not exactly represented by the figure of a cycle which returns into itself. What actually happens, in all but the lowest organisms, is that one part of the grow