On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for LifeJohn Murray, 1882 - 458페이지 |
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vii 페이지
... hybrids --- Sterility various in degree , not universal , affected by close interbreeding , re- moved by domestication - Laws governing the sterility of hybrids Sterility not a special endowment , but incidental on other differences ...
... hybrids --- Sterility various in degree , not universal , affected by close interbreeding , re- moved by domestication - Laws governing the sterility of hybrids Sterility not a special endowment , but incidental on other differences ...
xii 페이지
... hybrid moths . The discussion on the fertility of hybrids not having been ac- quired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . Pyrgoma found in the chalk ...
... hybrid moths . The discussion on the fertility of hybrids not having been ac- quired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . Pyrgoma found in the chalk ...
7 페이지
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , breeding freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state of nature ...
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , breeding freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state of nature ...
19 페이지
... hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile , as I can state from my own obser- vations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascertained with certainty ...
... hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile , as I can state from my own obser- vations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascertained with certainty ...
32 페이지
... hybrids and of mongrels , and the sterility of hybrids ; but plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change , the accumulative action of Selection ...
... hybrids and of mongrels , and the sterility of hybrids ; but plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change , the accumulative action of Selection ...
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adapted admit affinities allied species America analogous ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common progenitor continued crossed crustaceans degree developed difficulty distinct species doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formations formerly forms fossil Fritz Müller genera genus geological Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner Marsupials migration modified descendants natural selection naturalists nearly nest occasionally occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed theory tion variability variations varieties vary whilst whole wings young
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428 페이지 - In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.
424 페이지 - Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. But analogy may be a deceitful guide.
322 페이지 - Every species has come into existence coincident both in space and time with a pre-existing closely allied species.
23 페이지 - ... that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician's wand, by means of which he may summon into life whatever form and mould he pleases.
63 페이지 - If such do occur, can we doubt (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed.
426 페이지 - ... when we regard every production of nature as one which has had a long history; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor...
50 페이지 - Two canine animals, in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture.
3 페이지 - As many more individuals of each species are born than can possibly survive; and as, 'consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected.
63 페이지 - Several writers have misapprehended or objected to the term Natural Selection, Some have even imagined that natural selection induces variability, whereas it' implies only the. preservation of such variations as arise and are beneficial to the being under its conditions of * life.
388 페이지 - In my possession are two little embryos in spirit, whose names I have omitted to attach, and at present I am quite unable to say to what class they belong. They may be lizards or small birds, or very young mammalia, so complete is the similarity in the mode of formation of the head and trunk in these animals.