The Law of Heredity: A Study of the Cause of Variation, and the Origin of Living OrganismsJ. Murphy, 1883 - 336페이지 |
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35 페이지
... genus into a number of species and varieties , there is a similar branching in the wave - motion which is carried from the common ancestral form to the entire group of its de- scendants ; and each undulating branch implants in the same ...
... genus into a number of species and varieties , there is a similar branching in the wave - motion which is carried from the common ancestral form to the entire group of its de- scendants ; and each undulating branch implants in the same ...
63 페이지
... genus - Spathogaster baccarum . It is a soft green gall , punctated with red spots , and it grows entirely through the leaf , so that part is on the upper and part on the lower surface . The oak trees with these galls were kept ...
... genus - Spathogaster baccarum . It is a soft green gall , punctated with red spots , and it grows entirely through the leaf , so that part is on the upper and part on the lower surface . The oak trees with these galls were kept ...
66 페이지
... genus , Arbacia . A lot of Arbacia eggs were fertilized with a male Strongylo- centrotus , a lot from each form with fluid from a male of the same species , and eggs from each species were placed in water without fertilization . In all ...
... genus , Arbacia . A lot of Arbacia eggs were fertilized with a male Strongylo- centrotus , a lot from each form with fluid from a male of the same species , and eggs from each species were placed in water without fertilization . In all ...
92 페이지
... genus . Semper has shown ( Animal Life , p . 161 ) that certain definite changes in the size of the fresh - water snail Lymnæa are produced in a short time by confining it in a small quantity of water . These are a few of the cases ...
... genus . Semper has shown ( Animal Life , p . 161 ) that certain definite changes in the size of the fresh - water snail Lymnæa are produced in a short time by confining it in a small quantity of water . These are a few of the cases ...
101 페이지
... genus from another , have been acquired since the two diverged , and not even all of these slight differences , for a difference between two allied species may be due to the fact that while one has been modified the other has retained ...
... genus from another , have been acquired since the two diverged , and not even all of these slight differences , for a difference between two allied species may be due to the fact that while one has been modified the other has retained ...
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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...