Evolution and AdaptationMacmillan, 1903 - 470페이지 |
기타 출판본 - 모두 보기
자주 나오는 단어 및 구문
acquired characters adaptation adult ancestors animals and plants annelids appear arisen artificial selection become believe birds body breed cause color conclusion connection crustaceans Darwin Darwinian degeneration difficulty direction domestic eggs elementary species embryo environment evidence evolution existence experiments explain external fact females fertilized fish Fleischmann flowers fluctuating variations gemmules genus geotropic give habit hybrid hypothesis important individuals inheritance of acquired insects instance instinct intercrossing kind Lamarck Lamarckian large number later legs less light living males mammals ment mollusks mutation theory natural selection notochord occur offspring organs origin Origin of Species pangenesis parent form parthenogenetic polar body pollen present principle probable produced question races recapitulation theory regard reproduction reptiles resemblance result seeds sexes sexual selection shown side sort spermatozoon stages sterility structure supposed theory of natural tion transmitted transmutation theory variability varieties vertebrates Vries Weismann wings young
인기 인용구
131 페이지 - To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.
116 페이지 - Can the principle of selection, which we have seen is so potent in the hands of man, apply under nature? I think we shall see that it can act most efficiently. Let the endless number of slight variations and individual differences occurring in our domestic productions, and, in a lesser degree, in those under nature, be borne in mind ; as well as the strength of the hereditary tendency.
113 페이지 - The amount of food for each species of course gives the extreme limit to which each can increase ; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average numbers of a species.
119 페이지 - ... be, compared with those accumulated by nature during whole geological periods. Can we wonder, then, that nature's productions should be far "truer" in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly...
167 페이지 - This form of selection depends, not on a struggle for existence in relation to other organic beings or to external conditions, but on a struggle between the individuals of one sex, generally the males, for the possession of the other «ex. The result is not death to the unsuccessful competitor, but few or no offspring.
129 페이지 - LONG before the reader has arrived at this part of my work, a crowd of difficulties will have occurred to him. Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered...
117 페이지 - Variations neither useful nor injurious would not be affected by natural selection, and would be left either a fluctuating element, as perhaps we see in certain polymorphic species, or would ultimately become fixed, owing to the nature of the organism and the nature of the conditions.
116 페이지 - Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations, useful in some way to each being in the great and complex battle of life, should occur in the course of many successive generations ? If such do occur, can we doubt (remembering that many more...
108 페이지 - Again, it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species...
132 페이지 - To arrive, however, at a just conclusion regarding the formation of the eye, with all its marvellous yet not absolutely perfect characters, it is indispensable that the reason should conquer the imagination; but I have felt the difficulty far too keenly to be surprised at others hesitating to extend the principle of natural selection to so startling a length.