Are the Effects of Use and Disuse Inherited?: An Examination of the View Held by Spencer and DarwinMacmillan, 1890 - 156 páginas |
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Página 20
... collection of facts showing that " variation is the rule , " that the range of varia- tion in wild animals and plants is much greater than was supposed , and that " each part varies 20 ARE THE EFFECTS OF USE INHERITED ?
... collection of facts showing that " variation is the rule , " that the range of varia- tion in wild animals and plants is much greater than was supposed , and that " each part varies 20 ARE THE EFFECTS OF USE INHERITED ?
Página 55
... wild fowl , so that at this period there was danger of their flying away . " Is it not probable that the 1 Variation of Animals and Plants under Domestication , i . 292 . best fliers would escape most frequently , or would pine DUCKS ...
... wild fowl , so that at this period there was danger of their flying away . " Is it not probable that the 1 Variation of Animals and Plants under Domestication , i . 292 . best fliers would escape most frequently , or would pine DUCKS ...
Página 56
... wild and tame ducks similarly reared . If individual disuse diminished the weight of the duck's wing - bones by 9 per cent . there would be nothing left to account for . I suspect that investigation would reveal ano- malies inconsistent ...
... wild and tame ducks similarly reared . If individual disuse diminished the weight of the duck's wing - bones by 9 per cent . there would be nothing left to account for . I suspect that investigation would reveal ano- malies inconsistent ...
Página 59
... , since the exces- sive weight of the leg - bones increases the weight of the skeleton more than the diminished weight of the wing - bones reduces it . bones of the wild duck long and light . The DUCKS ' LEGS AND WINGS . 59.
... , since the exces- sive weight of the leg - bones increases the weight of the skeleton more than the diminished weight of the wing - bones reduces it . bones of the wild duck long and light . The DUCKS ' LEGS AND WINGS . 59.
Página 60
... wild duck long and light . The used leg - bones and the disused wing - bones have alike been shortened and thickened , though in different proportions . Natural or artificial selection might easily thicken legs without lengthening them ...
... wild duck long and light . The used leg - bones and the disused wing - bones have alike been shortened and thickened , though in different proportions . Natural or artificial selection might easily thicken legs without lengthening them ...
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Términos y frases comunes
acquired characters acquired modifications alleged Animals and Plants appears artificial selection atavism attributed Aylesbury duck become birds bones breeds cause cent civilization concomitant variation Contemporary Review Crown 8vo cumulative Darwin Descent deterioration diminished diminution diseases domestic animals domestic rabbit duck effects of ancestral effects of disuse enlarged epilepsy evidence evil explanation eyes fact factor of evolution fancy pigeons father favoured Francis Darwin Francis Galton Galton gemmules guinea-pigs heredity Illustrations improvement incisors increased individual inherited effects inherited injuries inherited mutilations insects instances instincts jaws Lamarckian leg-bones legs lengthened muscles natural or artificial natural selection nervous neuter offspring organs Origin of Species pangenesis panmixia parents pigeons Plants under Domestication quasi-inheritance race Ray Lankester reduced wings relative reproductive elements sexual selection shortened Spencer spite of disuse spontaneous variations sternum structure suppose tameness teeth tend tendency theory thickened sole tion toes transmit true inheritance use-inheritance Variation of Animals weight Weismann wing-bones
Pasajes populares
Página 26 - For peculiar habits confined to the workers or sterile females, however long they might be followed, could not possibly affect the males and fertile females, which alone leave descendants. I am surprised that no one has hitherto advanced this demonstrative case of neuter insects, against the well-known doctrine of inherited habit, as advanced by Lamarck.