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
... insects - Summary .. 191 CHAPTER IX . HYBRIDISM . Distinction between the sterility of first crosses and of hybrids - Sterility various in degree , not universal , affected by close interbreeding , removed by domestication - Laws ...
... insects - Summary .. 191 CHAPTER IX . HYBRIDISM . Distinction between the sterility of first crosses and of hybrids - Sterility various in degree , not universal , affected by close interbreeding , removed by domestication - Laws ...
Página 2
... insects under the bark of trees . In the case of the mistletoe , which draws its nourishment from certain trees , which has seeds that must be transported by certain birds , and which has flowers with separate sexes absolutely requiring ...
... insects under the bark of trees . In the case of the mistletoe , which draws its nourishment from certain trees , which has seeds that must be transported by certain birds , and which has flowers with separate sexes absolutely requiring ...
Página 32
... insects are far from uniform . Authors sometimes argue in a circle when they state that important organs never vary ; for these same authors practically rank those parts as important ( as some few naturalists have honestly confessed ) ...
... insects are far from uniform . Authors sometimes argue in a circle when they state that important organs never vary ; for these same authors practically rank those parts as important ( as some few naturalists have honestly confessed ) ...
Página 33
... insects , and in the immature and larval states of many of the lower animals . There are , also , cases of dimorphism and trimorphism , both with animals and plants . Thus , Mr. Wallace , who has lately called attention to the subject ...
... insects , and in the immature and larval states of many of the lower animals . There are , also , cases of dimorphism and trimorphism , both with animals and plants . Thus , Mr. Wallace , who has lately called attention to the subject ...
Página 34
... insects in North America and Europe , which differ very slightly from each other , have been ranked by one eminent naturalist as undoubted species , and by another as varieties , or , as they are often called , geographical races ! Mr ...
... insects in North America and Europe , which differ very slightly from each other , have been ranked by one eminent naturalist as undoubted species , and by another as varieties , or , as they are often called , geographical races ! Mr ...
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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