EvolutionH. Holt, 1911 - Всего страниц: 256 |
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active adapted amoeboid arise become biologists biology bird body breed called cells chapter character chemical colour Darwin definite distinct doctrine domestic dominant dwarfs embryo environment essentially Étienne Geoffroy Saint-Hilaire evidence Evolution of Sex evolution theory evolutionary evolutionist experience experimental expression fact factors fertilized flower forms fossil functional gametes genera genus germ germ-cells germinal Gregarines Heredity horse important individual inheritance interesting interpretation islands Lamarck Lamarckian less living creature male mammals Mendelian ment modern modifications mutation natural selection naturalists notochord occur organism Origin of Species ovum parasitism peculiarities pedigree physical plants and animals Professor progress Protists protoplasm Protozoa pure race recapitulation recessive regard relation reproductive reptiles resemblance result rustic seems sexual selection social structure struggle for existence success suggested survival T. H. Morgan tion tive to-day toes Tropidurus variations varieties vegetative vestigial structures vital vitalist Weismann wild
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Стр. 157 - 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?
Стр. 158 - It may metaphorically be said that natural selection is daily and hourly scrutinizing, throughout the world, the slightest variations ; rejecting those that are bad, preserving and adding up all that are good...
Стр. 146 - That which we were looking for, and could not find, was a hypothesis respecting the origin of known organic forms, which assumed the operation of no causes but such as could be proved to be actually at work.
Стр. 154 - Hence, as more individuals are produced than can possibly survive, there must in every case be a struggle for existence — either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life.
Стр. 148 - It is, therefore, of the highest importance to gain a clear insight into the means of modification and coadaptation. At the commencement of my observations it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed ; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the...
Стр. 37 - I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect ; of this history we possess the last volume alone, relating only to two or three countries. Ot this volume, only here and there a short chapter has been preserved ; and of each page, only here and there a few lines.
Стр. 160 - As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramifications.
Стр. 148 - ... 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. 117 - In many cases the future reproductive cells are visibly set apart at a very early stage before the division of labour in body-making has more than begun; in other cases where the future reproductive cells are not visible till much later, we argue by analogy that they are reproductive cells because they have not shared in body-making, but have kept intact the protoplasmic equipment — the full inheritance — of the original fertilized ovum. Thus the parent is rather the trustee of the germ-plasm...
Стр. 154 - I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny.