The Origin of Species by Means of Natural Selection: Or, the Preservation of Favored Races in the Struggle for Life, Volumen1D. Appleton, 1898 |
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Página xix
... marked by intervals of organic character , which we find to be a practical difficulty in ascertaining affini- ties ; second , of another impulse connected with the vital forces , tending , in the course of generations , to modify ...
... marked by intervals of organic character , which we find to be a practical difficulty in ascertaining affini- ties ; second , of another impulse connected with the vital forces , tending , in the course of generations , to modify ...
Página 9
... marked differences occasionally appear in the young of the same litter , and in seedlings from the same seed - capsule . At long intervals of time , out of millions of individuals reared in the same coun- try and fed on nearly the same ...
... marked differences occasionally appear in the young of the same litter , and in seedlings from the same seed - capsule . At long intervals of time , out of millions of individuals reared in the same coun- try and fed on nearly the same ...
Página 12
... marked influence ; thus I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more , in proportion to the whole skeleton , than do the same bones in the wild - duck ; and this change may be safely ...
... marked influence ; thus I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more , in proportion to the whole skeleton , than do the same bones in the wild - duck ; and this change may be safely ...
Página 16
... proving its truth : we may safely conclude that very many of the most strongly marked domestic varieties could not possibly live in a wild state . In many cases we do not know what. 16 VARIATION UNDER DOMESTICATION . [ CHAP . I.
... proving its truth : we may safely conclude that very many of the most strongly marked domestic varieties could not possibly live in a wild state . In many cases we do not know what. 16 VARIATION UNDER DOMESTICATION . [ CHAP . I.
Página 18
... marked distinction existed between a domestic race and a species , this source of doubt would not so perpetually recur . It has often been stated that domestic races do not differ from each other in character of generic value . It can ...
... marked distinction existed between a domestic race and a species , this source of doubt would not so perpetually recur . It has often been stated that domestic races do not differ from each other in character of generic value . It can ...
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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 colour common crossed cuckoo degree descendants developed difficulty distinct species disuse divergence domestic animals domestic races doubt effects eggs existence extinct extremely facts favourable females flowers forms Fritz Müller genera genus giraffe gradations greater number groups habits Hence hermaphrodites hive-bee important increase inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ large number larger genera larvæ less males manner Melipona Mivart modified natural selection naturalists nearly nest occasionally offspring organisation organs origin Origin of Species parent perfect period pigeons pollen pollen-grains present preserved prey principle probably produced progenitor quadrupeds rank rarely Red Grouse relation remarked resemble rock-pigeon seeds sexes sexual selection slight stamens striped structure struggle supposed swimbladder tend tendency tion tree variability variations varieties vary widely wings young