On the Origin of Species by Means of Natural Selection; Or, The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1861 - Всего страниц: 440 |
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Стр. 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 ...
Стр. 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 ...
Стр. 47
... insect would have been variable in the same species ; I should have expected that changes of this nature could have ... 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 have ... insects are very far from uniform . Authors sometimes argue in a circle when they state that important organs CHAP ...
Стр. 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 ...
Стр. 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 ...
Другие издания - Просмотреть все
The Origin of Species by Means of Natural Selection: Or, The ..., Том 1 Charles Darwin Полный просмотр - 1889 |
The Origin of Species by Means of Natural Selection: Or, the ..., Том 1 Charles Darwin Полный просмотр - 1898 |
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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 disuse 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 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 probably produced progenitor ranked reciprocal crosses remarked resemble rudimentary seeds seems sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation varieties vary whole widely
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Стр. 9 - After five years' work I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions, which then seemed to me probable: from that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.
Стр. 76 - When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply.
Стр. 171 - If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
Стр. 9 - Beagle,' as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geological relations of the present to the past inhabitants of that continent.
Стр. 70 - Firs on the distant hill-tops ; within the last ten years large spaces have been enclosed, and self-sown firs are now springing up in multitudes, so close together that all cannot live. When I ascertained that these young trees had not been sown or planted, I was so much surprised at their numbers that I went to several points of view, whence I could examine hundreds of acres of the unenclosed heath, and literally I could not see a single Scotch Fir, except the old planted clumps.
Стр. 72 - Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!
Стр. 72 - Newman, who has long attended to the habits of humble-bees, believes that " more than two-thirds of them are thus destroyed all over England.
Стр. 169 - To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.
Стр. 423 - Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed to be connected at the present day by intermediate gradations whereas species were formerly thus connected.
Стр. 212 - This difficulty, though appearing insuperable, is lessened, or, as I believe, disappears, when it is remembered that selection may be applied to the family, as well as to the individual, and may thus gain the desired end. Thus, a well-flavoured vegetable is cooked, and the individual is destroyed; but the horticulturist sows seeds of the same stock, and confidently expects to get nearly the same variety; breeders of cattle wish the flesh and fat to be well marbled together; the animal has been slaughtered,...