The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeJohn Murray, Albemarle Street., 1891 - 432 páginas |
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Página vii
... crossing - Dimorphism and Trimorphism - Fertility of varieties when crossed , and of their mongrel offspring not universal - Hybrids and mongrels compared independently of their fertility - Summary 219 b CHAPTER X. ON THE IMPERFECTION ...
... crossing - Dimorphism and Trimorphism - Fertility of varieties when crossed , and of their mongrel offspring not universal - Hybrids and mongrels compared independently of their fertility - Summary 219 b CHAPTER X. ON THE IMPERFECTION ...
Página xiv
... crossing of already existing forms , and much to use and disuse , that is , to the effects of habit . To this latter agency he seems to attribute all the beautiful adapta- tions in nature ; -such as the long neck of the giraffe for ...
... crossing of already existing forms , and much to use and disuse , that is , to the effects of habit . To this latter agency he seems to attribute all the beautiful adapta- tions in nature ; -such as the long neck of the giraffe for ...
Página xvi
... crossing . Rafinesque , in his ' New Flora of North America , ' published in 1836 , wrote ( p . 6 ) as follows : - " All species might have been varieties once , and many varieties are gradually becoming species by assuming constant and ...
... crossing . Rafinesque , in his ' New Flora of North America , ' published in 1836 , wrote ( p . 6 ) as follows : - " All species might have been varieties once , and many varieties are gradually becoming species by assuming constant and ...
Página 7
... crossing of distinct species , and that which may be observed with plants and animals when reared under new or unnatural con- ditions . Many facts clearly show how eminently susceptible the reproductive system is to very slight changes ...
... crossing of distinct species , and that which may be observed with plants and animals when reared under new or unnatural con- ditions . Many facts clearly show how eminently susceptible the reproductive system is to very slight changes ...
Página 11
... crossed , - a subject hereafter to be discussed ) , domestic races of the same . species differ from each other in the same manner as do the closely- allied species of the same genus in a state of nature , but the differ- ences in most ...
... crossed , - a subject hereafter to be discussed ) , domestic races of the same . species differ from each other in the same manner as do the closely- allied species of the same genus in a state of nature , but the differ- ences in most ...
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Términos y frases comunes
accumulated adapted admit affinities allied species America analogous ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species domestic animals doubt effects eggs embryo existing extinct extremely facts favourable female fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids 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 occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed tend theory tion variability variations varieties vary whilst whole wings young