The Origin of Species by means of Natural Selection, 6th Edition - The Original Classic Edition. Darwin Charles

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СКАЧАТЬ But it may be objected that if all organic beings thus tend to rise in the scale, how is it that throughout the world a multitude of the lowest forms still exist; and how is it that in each great class some forms are far more highly developed than others? Why have not

       the more highly developed forms every where supplanted and exterminated the lower? Lamarck, who believed in an innate and inevitable tendency towards perfection in all organic beings, seems to have felt this difficulty so strongly that he was led to suppose that new and simple forms are continually being produced by spontaneous generation. Science has not as yet proved the truth of this be-lief, whatever the future may reveal. On our theory the continued existence of lowly organisms offers no difficulty; for natural selection, or the survival of the fittest, does not necessarily include progressive development--it only takes advantage of such variations

       as arise and are beneficial to each creature under its complex relations of life. And it may be asked what advantage, as far as we can see, would it be to an infusorian animalcule--to an intestinal worm--or even to an earth-worm, to be highly organised. If it were no advantage, these forms would be left, by natural selection, unimproved or but little improved, and might remain for indefinite ages in their present lowly condition. And geology tells us that some of the lowest forms, as the infusoria and rhizopods, have remained for an enormous period in nearly their present state. But to suppose that most of the many now existing low forms have not in the least advanced since the first dawn of life would be extremely rash; for every naturalist who has dissected some of the beings now ranked as very low in the scale, must have been struck with their really wondrous and beautiful organisation.

       Nearly the same remarks are applicable, if we look to the different grades of organisation within the same great group; for instance, in the vertebrata, to the coexistence of mammals and fish--among mammalia, to the coexistence of man and the ornithorhyn-chus--among fishes, to the coexistence of the shark and the lancelet (Amphioxus), which latter fish in the extreme simplicity of its

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       structure approaches the invertebrate classes. But mammals and fish hardly come into competition with each other; the advancement

       of the whole class of mammals, or of certain members in this class, to the highest grade would not lead to their taking the place

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