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and four feet long, and on the hills an ugly yellowishbrown species equally common." On one occasion, "as I was walking along," he says, "I met two large tortoises, each of which must have weighed at least two hundred pounds (more than 14 stone): one was eating a piece of cactus, and as I approached, it stared at me and slowly stalked away; the other gave a deep hiss, and drew in its head. These huge reptiles, surrounded by the black lava, the leafless shrubs and large cacti, seemed to my fancy like some antediluvian animals. The few dullcoloured birds cared no more for me than they did for the great tortoises." We have a great deal more from Mr. Darwin about these huge hideous reptiles, whether tortoises or lizards, that is very interesting and strange. Both seem to swarm. The tortoises for food are open to capture at any time. "It is said that formerly single vessels have taken away as many as seven hundred, and that the ship's company of a frigate some years since brought down in one day two hundred tortoises to the beach." Vapour-crowned volcanic heights studded with orifices; miles and miles of black lava, red scoriæ, and dusty cinders; great black or yellow-hideous lizards sleeping in the sun'; huge monsters of tortoises lazily crawling along paths they have worn through centuries to where water lies: how startling it must be in the midst of such lonely weird sights as these to come suddenly on the ghastly gleaming skull of a buccaneer captain who had been murdered by his crew!

One cannot wonder that such a region as this went to the heart of Mr. Darwin, and remained ever afterwards with him a constant problem of the most intent and absorbing interest, - one cannot wonder that it was here he found the motive for his peculiar theory. The spot was solitary and remote; and what life there was upon it, seemed to have for him only a strange, unnatural, and

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old world look. The possible influence of isolation, simply as isolation, would probably first occur to him; and then, perhaps, the question, if the isolation had been the source of so many changed forms, how was it that there were others which had remained seemingly unchanged? Such conjectures appear at least not alien to the genius of a Darwin; but we must postpone our further consideration of these matters till the next week.

GIFFORD LECTURE THE TWENTIETH.

The action-South American types, left here to themselves, change into new species from accumulation of their own individual spontaneous differences-The birds-Differences in the times and modes of arrival between land and sea birds-Carte and tierce-Contradiction-Parried by a word-An advocate's proof -The printer and Mr. Darwin's woulds-The sea-gull-The finches Sir William Jardine-The process to Darwin-What was to him "a new birth"-Where the determinative advantage for these different beaks-The individual central islands not incommunicably separate-French birds at Dover-IsolationEx-contrario-Individual difference the single secret, that is the "law" which has been "discovered" of "natural selection' -Apply influence of external conditions to the GalapagosKant-The Galapagos rat and mouse-New beings but yet the old names-If difference goes always on only to difference without return to identity, why are there not infinitely more species?- Bowen - Darwin only empedoclean - Parsons -Lyell-Monsters (giants and dwarfs) sterile-Frederick's grenadiers, the pygmies - Divergent species at home Galapagos but the Mr. Jorkins of the Darwinians-The tortoise, where did it come from? -The amblyrhyncus similarly inexplicable-Lizards of the secondary epoch-The Galapagos Islands absolutely without a vestige of the struggle for life in any direction-The breeder, and nature, can act only on what is already there-The breeder deals in identity, not difference, and his breeds would all turn back to the original-No breeder a new species-Nature acts not on Darwin's method, but design -Toothed birds, the hipparion, the otter-sheep- Accidental individual difference to be the sole creator in the end of all that enormous and infinitely complicated concert to unity!Farewell.

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BEING now possessed of some idea of the scene of the action, we may proceed forthwith to this latter itself.

SOUTH AMERICAN TYPES.

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And that is, to this sole effect: That South American types of life became, in process of time, specifically changed in these islands of the Galapagos, in consequence of their isolation, as well partial as total. The types particularly selected to be dwelt on are the birds. "In the Galapagos Islands," says Mr. Darwin in the Origin (348), "there are 26 land-birds; of these 21 (or perhaps 23) are peculiar, whereas of the 11 marine birds only 2 are peculiar;" and this difference Mr. Darwin explained by difference in the numbers of the immigration and in the times of it. Species," he said, "occasionally arriving after long intervals of time in a new and isolated district, and having to compete with new associates, would be eminently liable to modification, and would often produce groups of modified descendants." We are to understand, that is, this to have been the case with the land-birds: they only "occasionally" arrived "after long intervals of time," and they had to "compete with new associates." As for the sea-birds, the excess of nonmodification in them was due, it is said, "partly" to their "having immigrated in a body, so that their mutual relations were not much disturbed," and "partly to the frequent arrival of unmodified immigrants from the mother-country, with which the insular forms have intercrossed." We see here that invariable felicity of Mr. Darwin that, if there is a foin in carte, it is as swiftly followed up by a fence in tierce. Few immigrants, at long intervals, give us modification-carte; but many immigrants, at frequent intervals, quite as much withdraw modification-tierce! Mr. Darwin blows hot and cold with equal vigour. It is only fair to observe, however, that Mr. Darwin has a reason why sea-birds have immigrated differently from land-birds. "It is obvious," he says, "that marine birds could arrive at these islands much more easily and frequently than land

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birds." But even here, in his own facts, is there not pretty well his own contradiction? If marine birds can immigrate more easily and frequently than land-birds, it at least sounds strange that, while there are 26 of the land, there are only 11 of the sea. It is quite possible, of course, as regards new species that the many come from the few, and, contrariwise, the few from the many. No one can doubt, at any rate, that Mr. Darwin's ingenuity could make it appear so. He can find a word at any moment that is an open sesamè to any difficulty. He says himself that, from end to end of it, his Origin of Species is one long argument." And so it is! From end to end of it, it is what the Germans call an Advocatenbeweis: from end to end of it, it is an advocate's proof. Even in what lies at this moment before us, just in the same way as we saw already, he that continues to read will find almost every proposition conditioned by a would. It is always this would take place, and that would take place. In point of actual fact, there are so many woulds in Mr. Darwin's books on natural selection, that one may be forgiven if one finds oneself speculating, with some curiosity, about the resources of a printer's fount. In this reference, and as concerns the many from the few or the few from the many, would it be unfair to say that one would not expect such an animal as a gull to be one of the only two remarkably modified sea-birds? One would expect it to arrive always in very large numbers, and on occasions of very frequent occurrence. From the known habits of the gull, one would expect this almost more in its case than in that of any other sea-bird-one would really, least of all, expect the gull to be the exceptional sea-bird to display in the Galapagos even as much modification as the land-birds. Mr. Darwin himself cannot help exclaiming here, "Considering the wandering habits of the gulls, I was surprised

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