The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, by Charles Darwin, with an Introduction by Edmund B. WilsonMacmillan, 1927 - 557 páginas |
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Página xii
... cells in their turn derive their hereditary con- stitution from preëxisting germ - cells . This is the view of heredity urged especially by Weismann and summed up in Samuel Butler's pithy saying , " the hen is only the egg way of making ...
... cells in their turn derive their hereditary con- stitution from preëxisting germ - cells . This is the view of heredity urged especially by Weismann and summed up in Samuel Butler's pithy saying , " the hen is only the egg way of making ...
Página xxxiii
... cell - making instinct - Changes of instinct and structure not necessarily simultaneous - Difficulties of the theory of the Natural Selection of instincts - Neuter or sterile insects Summary 204 249 CHAPTER IX HYBRIDISM Distinction ...
... cell - making instinct - Changes of instinct and structure not necessarily simultaneous - Difficulties of the theory of the Natural Selection of instincts - Neuter or sterile insects Summary 204 249 CHAPTER IX HYBRIDISM Distinction ...
Página 122
... cells , or became attached to any supporting surface , his law " that homologous units of any order become differ- entiated in proportion as their relations to incident forces become different " would come into action . But as we have ...
... cells , or became attached to any supporting surface , his law " that homologous units of any order become differ- entiated in proportion as their relations to incident forces become different " would come into action . But as we have ...
Página 162
... , on the other hand , an organ so wonderful as the eye ? Thirdly , can instincts be acquired and modified through natural selection ? What shall we say to the instinct which leads the bee to make cells , and which has 162.
... , on the other hand , an organ so wonderful as the eye ? Thirdly , can instincts be acquired and modified through natural selection ? What shall we say to the instinct which leads the bee to make cells , and which has 162.
Página 163
... cells , and which has practically antici- pated the discoveries of profound mathematicians ? Fourthly , how can we account for species , when crossed , being sterile and producing sterile offspring , whereas , when varieties are crossed ...
... cells , and which has practically antici- pated the discoveries of profound mathematicians ? Fourthly , how can we account for species , when crossed , being sterile and producing sterile offspring , whereas , when varieties are crossed ...
Términos y frases comunes
adapted admit affinities allied species analogous ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied color continued crossed crustaceans degree developed difficulty distinct species divergence doubt effects eggs embryo existing extinct extremely facts favorable females fertility flowers formation formerly forms fossil Fritz Müller genera genus geological Glacial period gradations groups of species habits Hence hybrids hybrids produced 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 organs Origin of Species parent peculiar perfect pigeon pistil pollen present principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed tend tion trees variability variations varieties vary whole widely different wings young