On the Origin of the Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeJohn Murray, 1869 - 596페이지 |
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9 페이지
... separated by any distinct line from slighter variations . All such changes of structure , whether extremely slight or strongly marked , which appear amongst many individuals living together , may be considered as the indefinite effects ...
... separated by any distinct line from slighter variations . All such changes of structure , whether extremely slight or strongly marked , which appear amongst many individuals living together , may be considered as the indefinite effects ...
55 페이지
... separated areas . How many of those birds . and 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 ...
... separated areas . How many of those birds . and 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 ...
107 페이지
... separation of the sexes of plants . Some holly - trees bear only male flowers , which have four stamens pro- ducing a rather small quantity of pollen , and a rudi- mentary pistil ; other holly - trees bear only female . flowers ; these ...
... separation of the sexes of plants . Some holly - trees bear only male flowers , which have four stamens pro- ducing a rather small quantity of pollen , and a rudi- mentary pistil ; other holly - trees bear only female . flowers ; these ...
108 페이지
... separation of the sexes of our plant would be advantageous on the principle of the division of labour , individuals with this tendency more and more increased , would be continually favoured or selected , until at last a complete separation ...
... separation of the sexes of our plant would be advantageous on the principle of the division of labour , individuals with this tendency more and more increased , would be continually favoured or selected , until at last a complete separation ...
111 페이지
... separated sexes , it is of course obvious that two individuals must always ( with the exception of the curious and not well - understood cases of parthenogenesis ) unite for each birth ; but in the case of hermaphrodites this is far ...
... separated sexes , it is of course obvious that two individuals must always ( with the exception of the curious and not well - understood cases of parthenogenesis ) unite for each birth ; but in the case of hermaphrodites this is far ...
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accumulated adapted affinities allied species America ancient appear Asa Gray become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt Edition eggs embryo existing exterminated extinct extremely facts favourable females fertilised fertility flowers formation forms fossil Fritz Müller Gärtner genera genus geological Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate larvæ less living males mammals manner migration modified descendants natural selection naturalists nearly nest occur oceanic islands offspring organisation parent perfect pigeons pistil pollen Post 8vo present principle probably produced progenitor racters ranked reciprocal crosses remarked resemble seeds sexual sexual selection Silurian slight South America stamens sterility structure struggle successive suppose theory tion variability variations varieties vary vols whole widely