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 56
... bones , & c . , of 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 ...
... bones , & c . , of 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 ...
Página 57
... bones of the Penguin duck have slightly diminished in length , although they have in- creased 39 per cent . in weight . " Relatively to the weight of the skeleton , the leg - bones ... wing DUCKS ' LEGS AND WINGS . 57.
... bones of the Penguin duck have slightly diminished in length , although they have in- creased 39 per cent . in weight . " Relatively to the weight of the skeleton , the leg - bones ... wing DUCKS ' LEGS AND WINGS . 57.
Página 58
... wing - bones is fully accounted for by the same circumstance , and disuse has had no inherited effect . Another strange circumstance is that the wing- bones have diminished in length only . The shorten- ing is about 6 per cent . more ...
... wing - bones is fully accounted for by the same circumstance , and disuse has had no inherited effect . Another strange circumstance is that the wing- bones have diminished in length only . The shorten- ing is about 6 per cent . more ...
Página 59
... wing- bones in this breed is only 8.3 per cent . relatively to the whole skeleton , or only 5 per cent . relatively to the skeleton minus legs and wings . The latter method is the more correct , since the exces- sive weight of the leg - ...
... wing- bones in this breed is only 8.3 per cent . relatively to the whole skeleton , or only 5 per cent . relatively to the skeleton minus legs and wings . The latter method is the more correct , since the exces- sive weight of the leg - ...
Página 60
... 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 , or shorten wings without eliminating ...
... 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 , or shorten wings without eliminating ...
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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.