On the Origin of Species by Means of Natural Selection: Or The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1888 - 458 páginas |
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Página v
... Difficulty of distinguishing between Varieties and Species - Origin of Domestic Varieties from one or more Species- Domestic Pigeons , their Differences and Origin - Principles of Selection , anciently fol- lowed , their Effects ...
... Difficulty of distinguishing between Varieties and Species - Origin of Domestic Varieties from one or more Species- Domestic Pigeons , their Differences and Origin - Principles of Selection , anciently fol- lowed , their Effects ...
Página vi
... DIFFICULTIES OF THE THEORY . - Difficulties of the theory of descent with modification Absence or rarity of ... difficulty - Natura non facit saltum - Organs of small importance - Organs not in all cases absolutely perfect- The ...
... DIFFICULTIES OF THE THEORY . - Difficulties of the theory of descent with modification Absence or rarity of ... difficulty - Natura non facit saltum - Organs of small importance - Organs not in all cases absolutely perfect- The ...
Página xiv
... difficulty of distinguishing species and varieties , by the almost perfect gradation of forms in certain groups , and by the analogy of domestic produc- tions . With respect to the means of modification , he attributed something to the ...
... difficulty of distinguishing species and varieties , by the almost perfect gradation of forms in certain groups , and by the analogy of domestic produc- tions . With respect to the means of modification , he attributed something to the ...
Página xvii
... difficulty in ascertaining affinities ; second , of another impulse connected with the vital forces , tending in the course of generations , to modify organic structures in accor dance with external circumstances , as food , the nature ...
... difficulty in ascertaining affinities ; second , of another impulse connected with the vital forces , tending in the course of generations , to modify organic structures in accor dance with external circumstances , as food , the nature ...
Página xix
... difficulty of dis- tinguishing species and varieties , and from the principle of general gradation , that species have been modified ; and he attributes the modification to the change of circumstances . The author ( 1855 ) has also ...
... difficulty of dis- tinguishing species and varieties , and from the principle of general gradation , that species have been modified ; and he attributes the modification to the change of circumstances . The author ( 1855 ) has also ...
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Términos y frases comunes
adapted admit affinities allied species America analogous ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids important 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 reproductive resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed tend theory tion variability variations varieties vary whilst whole wings young