Collected papers, Volumen4 |
Términos y frases comunes
adaptive radiation Africa American Museum anatomy ancestors animals appear Asia beds birds bones boys Bridger carnivores characters Chavaniac collections colors Cope Cope's Creodonts Cretaceous cusps Darwin dental dinosaurs discovery divergence Edentates Elephas Eocene Europe evolution expedition exploration extinct fauna fossil France French geologic Glacial HENRY FAIRFIELD OSBORN heterodont homodont horn horse human Iren Dabasu Jurassic Lamarck lower mammalia mammals Marsupials Mastodon Miocene Mlle modern molars Monotremes Mosasaurs Multituberculates Museum of Natural Natural History natural selection naturalist Neanderthal North America observed Oligocene Oreodons origin of species Painlevé paleontology paper period perissodactyl phylogeny physical Placentals Pleistocene Pliocene premolars present primitive principle Professor Puerco pupils races recent region reptiles reptilian rhinoceros rodents scientific skeleton skull South specimen stage Tapirs teeth Tertiary theory tion titanotheres triconodont tritubercular ungulates Upper Verrier vertebrate Wahsatch Wallace Washington-Lafayette School Zoological
Pasajes populares
Página 6 - has now been shown, though most briefly and imperfectly, how the law that "Every species lias come into existence coincident both in time and space with a preexisting closely allied species," connects together and renders intelligible a vast number of independent and hitherto unexplained facts. In February, 1858, during
Página 8 - Domestic animals are abnormal, irregular, artificial; they are subject to varieties which never occur and never can occur in a state of nature: their very existence depends altogether on human care; so far are many of them removed from that just proportion of faculties, that true balance of organization
Página 9 - having colors best adapted to concealment from their enemies would inevitably survive the longest. Returning from the Archipelago in 1862, he published in 1864 his pioneer paper, "The Malayan Papilionidœ or Swallow-tailed Butterflies, as illustrative of the Theory of Natural Selection," in which he at once took rank beside Bates and Müller as one of the great
Página 7 - Most or perhaps all the variations from the typical form of a species must have some definite effect, however slight, on the habits or capacities of the individuals. Even a change of color might, by rendering them more or less distinguishable, affect their safety; a greater or less development of hair might modify their habits. . . . The superior variety would then alone remain, and on a
Página 5 - Classification der fossilen Hufthiere, out of date in its facts, thoroughly modern in its approach to ancient nature. This work is a model union of the detailed study of form and function with theory and the working hypothesis. It regards the fossil not as a petrified skeleton, but as moving and feeding; every joint and facet
Página 4 - for otherwise," he writes, "it seems very unlikely that I should ever have undertaken what at that time seemed rather a wild scheme, a journey to the almost unknown forests of the Amazon in order to observe nature and make a living by collecting." In his autobiographic volumes of 1905, "My Life, a
Página 2 - on the other hand, may be distinguished from realms as geographical and zoological areas, which have been isolated from each other for shorter periods, either by climatic barriers, as in the case of the Arctic or circumpolar region, or by great physical barriers, such as masses of water and of desert