The Law of Heredity: A Study of the Cause of Variation, and the Origin of Living OrganismsJ. Murphy, 1883 - 336페이지 |
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54개의 결과 중 6 - 10개
80 페이지
... gemmules - Tendency to form gemmules is due to the direct action of external conditions - The ovum is the con- servative element - The male cell is the progressive element- This theory has features of resemblance to most of the hy ...
... gemmules - Tendency to form gemmules is due to the direct action of external conditions - The ovum is the con- servative element - The male cell is the progressive element- This theory has features of resemblance to most of the hy ...
82 페이지
... gemmules " of this particular cell . These germs may be carried to all parts of the body . They may penetrate to an ... gemmule " unites with , conjugates with , or impregnates , that particle of the ovum which is destined to give rise ...
... gemmules " of this particular cell . These germs may be carried to all parts of the body . They may penetrate to an ... gemmule " unites with , conjugates with , or impregnates , that particle of the ovum which is destined to give rise ...
83 페이지
... gemmules . According to this view , the origin of a new variation is neither purely fortuitous nor due to the direct ... gemmules , and thus to induce variability in the same cells of succeeding generations . Then , too , a gemmule may ...
... gemmules . According to this view , the origin of a new variation is neither purely fortuitous nor due to the direct ... gemmules , and thus to induce variability in the same cells of succeeding generations . Then , too , a gemmule may ...
84 페이지
... gemmules thrown off from cells like those in which the variation appears . Gemmules may penetrate to all parts of the body , and they may thus give rise to bud - variation and to analogous changes ; or they may penetrate to an ovarian ...
... gemmules thrown off from cells like those in which the variation appears . Gemmules may penetrate to all parts of the body , and they may thus give rise to bud - variation and to analogous changes ; or they may penetrate to an ovarian ...
85 페이지
... gemmules is essentially like Darwin's conception , and we must acknowledge that Buffon's view of the part played by his organic molecules was very near the truth . The analogy upon which Haeckel lays so much stress is readily explicable ...
... gemmules is essentially like Darwin's conception , and we must acknowledge that Buffon's view of the part played by his organic molecules was very near the truth . The analogy upon which Haeckel lays so much stress is readily explicable ...
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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 medusæ 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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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.
216 페이지 - ... males, victorious in contests over other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. If such females select the more attractive, and at the same time vigorous males, they will rear a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be if the more vigorous males select the more attractive and at the same time healthy and vigorous females; and this will especially...
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 or in their judgments. They persuade rather than convince, and value belief rather as a source of consolation than as...
282 페이지 - ... the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, should not be considered as subversive of the theory.
50 페이지 - 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.
282 페이지 - In living bodies, variation will cause the slight alterations, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. 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 those of man?
270 페이지 - Their imaginations individualize 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....
284 페이지 - 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. Species, however, probably change much more slowly, and within the same country only a few change at the same time. This slowness follows from all the inhabitants...
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.
266 페이지 - But this gravitation of women's minds to the present, to the real, to actual fact, while in its exclusiveness it is a source of errors, is also a most useful counteractive of the contrary error. 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...