On the Origin of Species by Means of Natural SelectionD. Appleton, 1870 - 440 páginas |
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Página 6
... insects - Summary , 185 CHAPTER VIII . 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 , 185 CHAPTER VIII . 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 11
... insects under the bark of trees . In the case of the misseltoe , which draws its nourishment from certain trees , which has seeds that must be transported by certain . birds , and which has flowers with separate sexes abso- lutely ...
... insects under the bark of trees . In the case of the misseltoe , which draws its nourishment from certain trees , which has seeds that must be transported by certain . birds , and which has flowers with separate sexes abso- lutely ...
Página 47
... insect would have been variable in the same species ; I should have expected that changes of this nature could nave ... insects are very far from uniform . Authors sometimes argue in a circle when they state that important organs CHAP ...
... insect would have been variable in the same species ; I should have expected that changes of this nature could nave ... insects are very far from uniform . Authors sometimes argue in a circle when they state that important organs CHAP ...
Página 48
... insects , and sev eral genera of Brachiopod shells . In most polymorphic genera some of the species have fixed and definite char- acters . Genera which are polymorphic in one country seem to be , with some few exceptions , polymorphic ...
... insects , and sev eral genera of Brachiopod shells . In most polymorphic genera some of the species have fixed and definite char- acters . Genera which are polymorphic in one country seem to be , with some few exceptions , polymorphic ...
Página 50
... 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 , as geographical races ...
... 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 , as geographical races ...
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Términos y frases comunes
accumulated adapted affinities allied species America amount ancient animals appear become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ laws less living look male mammals manner migration modification modified descendants natural selection naturalists nearly nest offspring organic organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rudimentary seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation varieties vary whole widely