Charles Darwin, NaturalistWilliam Brown, 1886 - Всего страниц: 32 |
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... means of Natural Selection . Few teachers have been regarded with such admiration by their disciples , or treated with so much respect by their opponents . No innovator has had less reason to complain of the indifference of his ...
... means of Natural Selection . Few teachers have been regarded with such admiration by their disciples , or treated with so much respect by their opponents . No innovator has had less reason to complain of the indifference of his ...
Стр. 4
... means the conditions to which domesticated organisms are subjected by man . Buffon also drew attention to the selection exerted by man on domesti- cated animals as a means of perpetuating variations . But although he mentions the great ...
... means the conditions to which domesticated organisms are subjected by man . Buffon also drew attention to the selection exerted by man on domesti- cated animals as a means of perpetuating variations . But although he mentions the great ...
Стр. 7
... means of supporting some sweep- ing generalization , which explains and holds together all the separate phenomena . In the first paper he pub- lished after his return from his voyage , he unites all the results of his studies of ...
... means of supporting some sweep- ing generalization , which explains and holds together all the separate phenomena . In the first paper he pub- lished after his return from his voyage , he unites all the results of his studies of ...
Стр. 8
... means in the pro- duction of new races . Having attended to the habits of animals and their relations to the surrounding conditions , I was able to realize the severe struggle for existence to which all organisms are subjected ; and my ...
... means in the pro- duction of new races . Having attended to the habits of animals and their relations to the surrounding conditions , I was able to realize the severe struggle for existence to which all organisms are subjected ; and my ...
Стр. 11
... means of modifica- tion and co - adaptation . To do this the author studies domesticated animals and cultivated plants . First of all are considered the causes of variability , which , as we shall have occasion to suggest later , are as ...
... means of modifica- tion and co - adaptation . To do this the author studies domesticated animals and cultivated plants . First of all are considered the causes of variability , which , as we shall have occasion to suggest later , are as ...
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action of natural America Animals and Plants anthropomorphic arguments Aspalax belief biologists Buffon caudicle cause of modification causes of variation characters CHARLES DARWIN chlorophyll conception cross-fertilization is effected Darwin points descendants descent with modification divergence earth environment Erasmus Darwin evolved external conditions favourable flower fossil Galapagos Islands geographical distribution given species gradual greater number habits Herbert Spencer human selection hypothesis idea increase inhabitants inherited instance intermediate links larger number lated the variations leave more progeny lowly organized forms Madeira beetles modifica morphological rela natural selection naturalist number of cats number of individuals offspring organic evolution Origin of Species parents perfectly adapted pheno phenomena Plants under Domestication pollinium present probable process of selection produced protoplasm question reproductive cells structure struggle for existence studies domesticated animals survival tend theory of evolution theory of natural thought tion truth of organic Tucutuco universal evolution variability wants or pleasures whole species woodpecker
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Стр. 29 - There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
Стр. 13 - There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair.
Стр. 10 - ... species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration.
Стр. 24 - In one sense the conditions of life may be said, not only to cause variability, either directly or indirectly, but likewise to include natural selection ; for the conditions determine whether this or that variety shall survive. But when man is the selecting agent, we clearly see that the two elements of change are distinct ; variability is in some manner excited, but it is the will of man which accumulates the variations in certain directions ; and it is this latter agency which answers to the survival...
Стр. 9 - ... free access to it from other countries be circumscribed, and let the change of conditions continue progressing (forming new stations), in such a case the original inhabitants must cease to be as perfectly adapted to the changed conditions as they were originally. It has been shown in a former part of this work, that such changes of external conditions would, from their acting on the reproductive system, probably cause the organization of those beings which were most affected to become, as under...
Стр. 32 - FLOWER in the crannied wall, I pluck you out of the crannies, I hold you here, root and all, in my hand, Little flower — but if I could understand What you are, root and all, and all in all, I should know what God and man is.
Стр. 22 - Thus, as I believe, natural selection will tend in the long run to reduce any part of the organisation, as soon as it becomes, through changed habits, superfluous, without by any means causing some other part to be largely developed in a corresponding degree. And, conversely, that natural selection may perfectly well succeed in largely developing...
Стр. 10 - ... trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself.
Стр. 10 - Naturalists continually refer to external conditions, such as climate, food, &c., as the only possible cause of variation. In one limited sense, as we shall hereafter see, this may be true ; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees.
Стр. 6 - This wonderful relationship in the same continent between the dead and the living, will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth and their disappearance from it than any other class of facts.