The Law of Heredity: A Study of the Cause of Variation, and the Origin of Living OrganismsJ. Murphy, 1883 - 336페이지 |
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11 페이지
... hydroids heredity may mani- fest itself by the formation of new animals , with all the characteristics of the parent , on almost any part of the body of the latter , and in certain plants the smallest fragment of tissue may become a new ...
... hydroids heredity may mani- fest itself by the formation of new animals , with all the characteristics of the parent , on almost any part of the body of the latter , and in certain plants the smallest fragment of tissue may become a new ...
112 페이지
... hydroids an egg - em- bryo may give rise , by budding , to certain descendants . with fully developed digestive organs , but with no or- gans of locomotion or reproductive organs , to other de- scendants with organs of locomotion , but ...
... hydroids an egg - em- bryo may give rise , by budding , to certain descendants . with fully developed digestive organs , but with no or- gans of locomotion or reproductive organs , to other de- scendants with organs of locomotion , but ...
115 페이지
... hydroids like itself , and each of these may give rise to other hydroids , and so on indefinitely . Each one of these may also , under certain conditions , give rise to medusæ quite different from the hydroids and like the original ...
... hydroids like itself , and each of these may give rise to other hydroids , and so on indefinitely . Each one of these may also , under certain conditions , give rise to medusæ quite different from the hydroids and like the original ...
116 페이지
... hydroids like itself , they also would have the power to grow into mature mcdusæ . We can also understand that ... hydroids without a medusa stage , and hydroids with a medusa stage . The suppression of the hydra features of the latter ...
... hydroids like itself , they also would have the power to grow into mature mcdusæ . We can also understand that ... hydroids without a medusa stage , and hydroids with a medusa stage . The suppression of the hydra features of the latter ...
249 페이지
... hydroids and sponges , the process is still more sim- ple , and cells may become converted into a bud at almost any point upon the body of the parent . That the pro- cess of reproduction by budding is not in any way abso- lutely ...
... hydroids and sponges , the process is still more sim- ple , and cells may become converted into a bud at almost any point upon the body of the parent . That the pro- cess of reproduction by budding is not in any way abso- lutely ...
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acquired action adult alike allied species ancestor ancestral form asexual asexual reproduction become birds body breed characteristics color common conclusion confined crossing crustacea Daphnia Darwin Darwin says descendants domesticated animals domesticated pigeons embryo epigenesis evolution existence experience explanation fact female fertilized fortuitous fowls functions furnishes gemmules genera genus germ germinative vesicle give rise gradually greatly hereditary homology horns hybrid hydroids hypothesis individual influence inherited insects latent male cell male element males of allied medusa ment modification natural selection offspring ordinary origin origin of species ovum pangenesis parent parthenogenesis peculiarities perfect phenomena plants plastidules plumage present produced pure race reasons for believing reciprocal crosses reproductive elements resemblance result secondary sexual characters sexes sexual elements sexual reproduction sexual selection similar simply striped structure tendency to vary theory of heredity throw off gemmules tion transmission transmit true variable various young
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282 페이지 - Let this process go on for millions of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man?
270 페이지 - I have already employed, women very rarely love truth, though they love passionately what they call ' the truth,' or opinions they have received from others, and hate vehemently those who differ from them. They are little capable of impartiality or of doubt ; their thinking is chiefly a mode of feeling ; though very generous in their acts, they are rarely generous in their opinions, and their leaning is naturally to the side of restriction.
50 페이지 - Lastly, I assume that the gemmules in their dormant state have a mutual affinity for each other, leading to their aggregation into buds or into the sexual elements.
266 페이지 - The principal and most characteristic aberration of speculative minds as such, consists precisely in the deficiency of this lively perception and ever-present sense of objective fact. For want of this, they often not only overlook the contradiction which outward facts oppose to their theories, but lose sight of the legitimate purpose of speculation altogether, and let...
215 페이지 - Just as man can improve the breed of his gamecocks by the selection of those birds which are victorious in the cockpit, so it appears that the strongest and most vigorous males, or those provided with the best weapons, have prevailed under nature, and have led to the improvement of the natural breed or species.
282 페이지 - ... the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.
284 페이지 - ... guidance of methodical selection. The comparison would be in every way fairer with the effects which follow from unconscious selection, that is the preservation of the most useful or beautiful animals, with no intention of modifying the breed ; but by this process of unconscious selection, various breeds have been sensibly changed in the course of two or three centuries.
50 페이지 - Their development is supposed to depend on their union with other partially developed cells or gemmules which precede them in the regular course of growth. Why I use the term union will be seen when we discuss the direct action of pollen on the tissues of the mother-plant. Gemmules are supposed to be thrown off by every cell or unit, not only during the adult state, but during all the stages of development.
270 페이지 - Their imaginations individualise more ; their affections are, in consequence, concentrated rather on leaders than on causes ; and if they care for a great cause, it is generally because it is represented by a great man, or connected with some one whom they love. In politics, their enthusiasm is more naturally loyalty than patriotism. In history, they are even more inclined than men to dwell exclusively upon biographical incidents or characteristics as distinguished from the march of general causes....
142 페이지 - These several conditions alone render it probable that variability of every kind is directly or indirectly caused by changed conditions of life. Or, to put the case under another point of view, if it were possible to expose all the individuals of a species during many generations to absolutely uniform conditions of life, there would be no...