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 vii
... insects - - Summary - 205-234 CHAPTER IX . HYBRIDISM .. Distinction between the sterility of first crosses and of hybrids — Sterility various in degree , not universal , affected by close interbreeding , re- moved by domestication ...
... insects - - Summary - 205-234 CHAPTER IX . HYBRIDISM .. Distinction between the sterility of first crosses and of hybrids — Sterility various in degree , not universal , affected by close interbreeding , re- moved by domestication ...
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 35
... 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 37
... 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 ...
Página 38
... insects which are charac- terized as varieties in Mr. Wollaston's admirable work , but which would certainly be ... insects live on one kind of plant or on one group of plants ; some feed indiscriminately on many kinds , but do not in ...
... insects which are charac- terized as varieties in Mr. Wollaston's admirable work , but which would certainly be ... insects live on one kind of plant or on one group of plants ; some feed indiscriminately on many kinds , but do not in ...
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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