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acquired adapted advantage allied analogous animals and plants appear Asa Gray beak become bees believe birds breeds caudicle cause cells characters climate closely colour common crossed cuckoo degree developed difficulty distinct species disuse divergence domestic animals domestic races doubt effects eggs existence extinct extremely facts favourable females flowers forms genera genus giraffe gradations greater number groups habits Hence hermaphrodites hive-bee important improved individual differences inhabitants inherited insects instance instincts intercrossing intermediate kind large number larger genera less likewise males manner Melipona Mivart natural selection naturalists nearly nest occasionally offspring organisation organs origin ORIGIN OF SPECIES parent pedicellariae perfect period pigeons Pleuronectidae pollen pollen-grains present preserved principle probably produced progenitor pupae quadrupeds rank Red Grouse remarked resemble rock-pigeon seeds sexes sexual sexual selection slight stamens striped structure struggle supposed swimbladder tend tendency tion transitional tree variability variations varieties vary widely wings young
Página 245 - If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection.
Página 93 - Several writers have misapprehended or objected to the term Natural Selection, Some have even imagined that natural selection induces variability, whereas it' implies only the. preservation of such variations as arise and are beneficial to the being under its conditions of * life.
Página 5 - As many more individuals of each species are born than can possibly survive ; and as, consequently, there is a frequently recurring straggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected.
Página xxiii - In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.
Página 162 - It is well known that several animals, belonging to the most different classes, which inhabit the caves of Carniola and of Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is gone; — the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could be in any way injurious to animals living in darkness, their loss may be attributed to disuse.
Página 73 - Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult — at least I have found it so — than constantly to bear this conclusion in mind.
Página 359 - Cloth, $2.00. DIFFERENT FORMS OF FLOWERS ON PLANTS OF THE SAME SPECIES. With Illustrations. 12mo. Cloth, $1.50. THE POWER OF MOVEMENT IN PLANTS. By CHARLES DARWIN, LL. D., FRS, assisted by FRANCIS DARWIN.
Página 154 - The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connection of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups.
Página 154 - The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species ; and those produced during each former year may represent the long succession of extinct species.