On the Origin of Species by Means of Natural Selection; Or, The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1861 - 440페이지 |
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92 페이지
... Gärtner , any in- fluence from the foreign pollen . When the stamens of a flower suddenly spring towards the pistil , or slowly move one after the other towards it , the contrivance seems adapted solely to ensure self - fertili- sation ...
... Gärtner , any in- fluence from the foreign pollen . When the stamens of a flower suddenly spring towards the pistil , or slowly move one after the other towards it , the contrivance seems adapted solely to ensure self - fertili- sation ...
218 페이지
... Gärtner also , makes the rule equally universal ; and he disputes the entire fertility of Kölreuter's ten cases . But in these and in many other cases , Gärtner is obliged carefully to count the seeds , in order to show that there is ...
... Gärtner also , makes the rule equally universal ; and he disputes the entire fertility of Kölreuter's ten cases . But in these and in many other cases , Gärtner is obliged carefully to count the seeds , in order to show that there is ...
219 페이지
... Gärtner were potted , and apparently were kept in a chamber in his house . That these processes are often injurious to the fertility of a plant cannot be doubt- ed ; for Gärtner gives in his table about a score of cases of plants which ...
... Gärtner were potted , and apparently were kept in a chamber in his house . That these processes are often injurious to the fertility of a plant cannot be doubt- ed ; for Gärtner gives in his table about a score of cases of plants which ...
220 페이지
... Gärtner was enabled to rear some hy- brids , carefully guiding them from a cross with either pure parent , for six or seven , and in one case for ten gen- erations , yet he asserts positively that their fertility never increased , but ...
... Gärtner was enabled to rear some hy- brids , carefully guiding them from a cross with either pure parent , for six or seven , and in one case for ten gen- erations , yet he asserts positively that their fertility never increased , but ...
221 페이지
... Gärtner that some degree of sterility between distinct species is a universal law of nature . He experimentised on some of the very same species as did Gärtner . The difference in their re- sults may , I think , be in part accounted for ...
... Gärtner that some degree of sterility between distinct species is a universal law of nature . He experimentised on some of the very same species as did Gärtner . The difference in their re- sults may , I think , be in part accounted for ...
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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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9 페이지 - 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.
76 페이지 - 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.
171 페이지 - 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.
9 페이지 - 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.
70 페이지 - 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.
72 페이지 - 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!
72 페이지 - 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.
169 페이지 - 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.
423 페이지 - 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.
212 페이지 - 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,...