The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen1D. Appleton & Company, 1889 |
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Página 26
... males and females have come to differ in a slight degree from each other . Altogether at least a score of pigeons might be chosen , which , if shown to an ornithologist , and he were told that they were wild birds , would certainly be ...
... males and females have come to differ in a slight degree from each other . Altogether at least a score of pigeons might be chosen , which , if shown to an ornithologist , and he were told that they were wild birds , would certainly be ...
Página 32
... male and female pigeons can be easily mated for life ; and thus different breeds can be kept together in the same aviary . I have discussed the probable origin of domestic pigeons at some , yet quite insufficient , length ; because when ...
... male and female pigeons can be easily mated for life ; and thus different breeds can be kept together in the same aviary . I have discussed the probable origin of domestic pigeons at some , yet quite insufficient , length ; because when ...
Página 55
... males of certain Brazilian Crustaceans : thus , the male of a Tanais regularly occurs under two distinct forms ; one of these has strong and differently shaped pincers , and the other has antennæ much more abundantly furnished with ...
... males of certain Brazilian Crustaceans : thus , the male of a Tanais regularly occurs under two distinct forms ; one of these has strong and differently shaped pincers , and the other has antennæ much more abundantly furnished with ...
Página 56
... male ; and that an hermaphrodite plant should produce from the same seed - capsule three distinct hermaphrodite forms , bearing three different kinds of females and three or even six different kinds of males . Never- theless these cases ...
... male ; and that an hermaphrodite plant should produce from the same seed - capsule three distinct hermaphrodite forms , bearing three different kinds of females and three or even six different kinds of males . Never- theless these cases ...
Página 60
... males alone , in other instances both males and females , have been observed thus to differ in a slight degree . When the differences are rather more strongly marked , and when both sexes and all ages are affected , the forms are ranked ...
... males alone , in other instances both males and females , have been observed thus to differ in a slight degree . When the differences are rather more strongly marked , and when both sexes and all ages are affected , the forms are ranked ...
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Términos y frases comunes
adapted advantage allied analogous animals and plants appear Asa Gray beak become bees believe birds breeds caudicle cause cells characters climate closely Cloth colour common crossed cuckoo degree descendants developed difficulty distinct species disuse domestic animals domestic races doubt effects eggs existence extinct extremely facts favourable females flowers forms Fritz Müller genera genus gradations greater number groups habits Hence hermaphrodites hive-bee important improved inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ large number larger genera larvæ less likewise males manner Mivart modified natural selection naturalists nearly nest neuters occasionally offspring organisation organs origin ORIGIN OF SPECIES parent perfect period pigeons pollen pollen-grains present preserved principle probably produced progenitor quadrupeds rank Red Grouse remarked resemble rock-pigeon seeds sexes sexual sexual selection slight stamens structure struggle sub-breeds supposed swimbladder tend tendency tion transitional tree tumbler pigeon variability variations varieties vary widely wild wings young
Pasajes populares
Página 227 - 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 203 - If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
Página 75 - 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 xxv - 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 xix - 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 144 - 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 55 - 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 341 - 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 140 - 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 140 - 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.