On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeEaston Press, 1976 - 470 páginas |
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Página 15
... mongrel offspring are very apt suddenly to acquire these characters . To give one instance out of several which I ... mongrels were dusky and mottled . I then crossed one of the mongrel barb - fantails with a mongrel barb - spot , and ...
... mongrel offspring are very apt suddenly to acquire these characters . To give one instance out of several which I ... mongrels were dusky and mottled . I then crossed one of the mongrel barb - fantails with a mongrel barb - spot , and ...
Página 268
... mongrels and hybrids : Gärtner states that mongrels are more liable than hybrids to revert to either parent - form ; but this , if it be true , is certainly only a difference in degree . Moreover , Gärtner expressly states that hybrids ...
... mongrels and hybrids : Gärtner states that mongrels are more liable than hybrids to revert to either parent - form ; but this , if it be true , is certainly only a difference in degree . Moreover , Gärtner expressly states that hybrids ...
Página 269
... mongrel plants from a reciprocal cross . Both hybrids and mongrels can be reduced to either pure parent - form , by repeated crosses in successive generations with either parent . These several remarks are apparently applicable to ...
... mongrel plants from a reciprocal cross . Both hybrids and mongrels can be reduced to either pure parent - form , by repeated crosses in successive generations with either parent . These several remarks are apparently applicable to ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
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Términos y frases comunes
accumulated adapted admit affinities allied species America ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common progenitor continuous crossed crustaceans degree developed difficulty distinct species divergence doubt effects eggs embryo existing exterminated extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gradations greater number groups of species habits Hence hybrids hybrids produced important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs Origin of Species parent peculiar perfect pigeons pistil plants pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds slight South America stamens sterility structure struggle successive supposed swimbladder theory variability variations varieties vary whilst whole wings young