On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
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Página 3
... 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 42
... insect would have been variable in the same species ; I should have expected that changes of this nature could have been effected only by slow degrees : yet quite recently Mr. Lubbock has shown a degree of variability in these main ...
... insect would have been variable in the same species ; I should have expected that changes of this nature could have been effected only by slow degrees : yet quite recently Mr. Lubbock has shown a degree of variability in these main ...
Página 43
... insects are very far from uniform . Authors sometimes argue in a circle when they state that important organs never vary ; for these same authors practically rank that character as important ( as some few naturalists have honestly ...
... insects are very far from uniform . Authors sometimes argue in a circle when they state that important organs never vary ; for these same authors practically rank that character as important ( as some few naturalists have honestly ...
Página 45
... 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 ...
Página 51
... insects of two districts , into two nearly equal masses , the species of the larger genera on one side , and those of the smaller genera on the other side , and it has invariably proved to be the case that a larger pro- portion of the ...
... insects of two districts , into two nearly equal masses , the species of the larger genera on one side , and those of the smaller genera on the other side , and it has invariably proved to be the case that a larger pro- portion of the ...
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Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence 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 land larvæ less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely