The Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeF. Ungar Publishing Company, 1956 - 134페이지 |
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42 페이지
... developed part tends to be highly variable . The rule applies only to a part unusually developed in comparison with the same part in closely allied species . Thus , the wing of a bat is a most abnormal structure in mammals , but the ...
... developed part tends to be highly variable . The rule applies only to a part unusually developed in comparison with the same part in closely allied species . Thus , the wing of a bat is a most abnormal structure in mammals , but the ...
43 페이지
... developed in an extraordinary manner in any one species , we may conclude it has undergone an extraordinary amount of modification since the several species branched off from the common progenitor . Extraordinary modification im- I ...
... developed in an extraordinary manner in any one species , we may conclude it has undergone an extraordinary amount of modification since the several species branched off from the common progenitor . Extraordinary modification im- I ...
79 페이지
... developed . Lastly , an embryo may be developed and perish at an early period . Mr. Salter has examined about 500 eggs from various crosses ; the majority had been fer- tilised ; and in the majority of the fertilised eggs , the embryos ...
... developed . Lastly , an embryo may be developed and perish at an early period . Mr. Salter has examined about 500 eggs from various crosses ; the majority had been fer- tilised ; and in the majority of the fertilised eggs , the embryos ...
목차
Variation under Domestication | 1 |
Variation under Nature | 12 |
Struggle for Existence | 19 |
저작권 | |
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accumulated adapted affinity allied species animals aphides appear areas become believe birds breeds Cambrian characters CHARLES DARWIN climate closely allied common continent crossed crustaceans cuckoo Darwin degree descended developed difficulty distinct species disuse domestic effects eggs embryo embryology eminently liable existing extermination extinct extremely fact favourable females fertilised fertility flower formations fossil genera genus geological geological period giraffe gradations greater number groups habits Hence hybrids hybrids produced important increase individuals inhabitants inheritance insects instance instincts intercrossing intermediate intervals islands larvae less living males mammals manner Marsupials migration Mivart modification natural selection naturalists nearly nest neuters occasional offspring organisation Origin of Species parent perfect pigeon plants pollen probably produced progenitor pupae quadrupeds rank reciprocal crosses reproductive systems resemblance rock-pigeon rudimentary organs seeds sexual selection slaves slight stage sterility structure struggle swimbladder tend tendency theory of natural tion variability variations varieties vary widely young