The Doctrine of Descent and DarwinismD. Appleton, 1875 - 334 páginas |
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Página 35
... genera , and tufts of species , which latter ramify into sub - species and varieties . With this representation of the tree - like distribution of the system , we shall gladly revert to the comparison of the members of different types ...
... genera , and tufts of species , which latter ramify into sub - species and varieties . With this representation of the tree - like distribution of the system , we shall gladly revert to the comparison of the members of different types ...
Página 42
... genera of coral depends merely on minor modifications of this mode of reproduction . Yet single corals exist in which , on careful comparison , not only may accidental deviations be already discerned , but regularly recurring variations ...
... genera of coral depends merely on minor modifications of this mode of reproduction . Yet single corals exist in which , on careful comparison , not only may accidental deviations be already discerned , but regularly recurring variations ...
Página 46
... genera- tion arise cell - spheres , or germs , which develope into the second generation - the Cercaria . Great excitement was likewise aroused by the dis- covery of the germ - formation of the larvæ of 46 THE DOCTRINE OF DESCENT .
... genera- tion arise cell - spheres , or germs , which develope into the second generation - the Cercaria . Great excitement was likewise aroused by the dis- covery of the germ - formation of the larvæ of 46 THE DOCTRINE OF DESCENT .
Página 57
... genera , which , by all systematic rules , and by their geological position , occupy a lower rank in the series of echino- derms . The crabs , or anourous crustacea , are raised by sundry characteristics above their long - tailed ...
... genera , which , by all systematic rules , and by their geological position , occupy a lower rank in the series of echino- derms . The crabs , or anourous crustacea , are raised by sundry characteristics above their long - tailed ...
Página 77
... genera and species distinguished from one another by mere shades , so that of two allied genera it is often difficult , nay , impossible , to state which TRANSFORMATIONS OF THE ECHINE . 77.
... genera and species distinguished from one another by mere shades , so that of two allied genera it is often difficult , nay , impossible , to state which TRANSFORMATIONS OF THE ECHINE . 77.
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according adaptation already Ammonites Amphibians animal world apes appearance Ascidian birds body bone brain causes Cetacea character characteristics comparative anatomy complete connection continent Darwin dentition derivation diverge doctrine of Descent Echinoderms embryo Eocene exhibit existence external facts families fauna fish formation fossil Gastrula gemmules genera genus geological Goethe grade gradually groups Haeckel heredity higher horse human hypothesis idea individual infer intermediate forms investigation islands lancelet language larva larvæ likewise linguistic lower mammals Marsupials Medusa ment merely metamorphosis modifications morphological mutability natural selection observations Oolite organisms origin ovum peculiar pedigree perfect period phase phenomena placenta plants polypes possess present primordial progenitors races regard relations remains reproduction reptiles Rütimeyer says scarcely scientific separate sexual Silurian skull species strata structure systematic terrestrial animals theory of selection tion transformation true Ungulata Ungulates varieties vertebral column Vertebrata vertebrate animals whole