Another fairly obvious deduction could be made. Who brought about the transformation? Lyell proved that, without any catastrophes, terrestrial things are constantly changing—the water and the land, the mountains and the valleys, and even the climate. In this gradual change the environments of living things were at length altered to such an extent that they were bound to cause a change in the organisms. However, different species reacted in different ways. Some gradually died out. Others adapted themselves to the new conditions; just as, in human affairs, one race breaks down under changed conditions while another rises to a higher and richer and new stage on that very account. No creation! Merely transformations of species, development of new forms from older ones by adaptation to new, naturally modified conditions. Even zoology and botany were without the finger of God from the earliest days. Of course there was no trace of these latter deductions in Lyell. But they pressed themselves with an irresistible and decisive force on the mind of one of his first readers, Darwin. He took Lyell’s book with him to South America. Step by step the logic of it forced him to admit that this was what must have taken place somewhere. First the idea of “extinct species” became a concrete picture to him there, a sort of diabolic vision. The whole substratum of the pampas is one colossal tomb of strange monsters. The bones lie bare at every outcrop. Megatheria, or giant-sloths, as large as elephants, and with thighbones three times as thick as that of the elephant, able to break off branches in the primitive forests with their paws: armadilloes as big as rhinoceroses, with coats as hard as stone and curved like barrels; gigantic llamas, the macrouchenias, compared with which the modern specimens are Liliputians; mastodons and wild horses, of which America was entirely free even in the days of Columbus, and lion-like carnivores with terrible sabre-teeth. There they all are to-day—extinct, lost, buried in the deserted cemetery of the pampas-loam. When the young Darwin stood by these groves, like Hamlet, he did not know how closely this ghost-world came to our own day. At that time the armour of the gigantic armadillo, the glyptodon, that had formed shelters over the heads of the human dwellers in the pampas, like Esquimaux huts, had not yet been discovered. The cave of Ultima Esperanza in Patagonia had not been searched, and no one had seen the red-haired coat of the sloth as large as an ox, the gryptotherium (a relative of the real megatherium), cut by some prehistoric human hand, amongst a heap, several yards deep, of the animal’s manure—in such peculiar circumstances as to prompt the suggestion that the giant-sloths had been kept tame in the cavern, as in a cyclopean stable, by prehistoric Indians. Darwin thought the remains were very old, though this by no means lessened the inspiration.