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 21
... lengthened wing might be gained in one genera- tion , and the strengthened muscle at a subse- quent period ; the bird in the meanwhile drawing upon its surplus energy , aided ( as I would suggest ) by the strengthening effect of ...
... lengthened wing might be gained in one genera- tion , and the strengthened muscle at a subse- quent period ; the bird in the meanwhile drawing upon its surplus energy , aided ( as I would suggest ) by the strengthening effect of ...
Página 57
... lengthened considerably so that their total deficiency in proportional length is 17 per cent . , - a changed proportion which being linear is more excessive than the increase of weight by 28 per cent . So marked is the effect of the ...
... lengthened considerably so that their total deficiency in proportional length is 17 per cent . , - a changed proportion which being linear is more excessive than the increase of weight by 28 per cent . So marked is the effect of the ...
Página 63
... lengthened in spite of disuse . Excluding the feathers , the wings were shorter in seventeen instances , and longer in eight . But as artificial selection has lengthened the wings in some instances , why may it not it not have have ...
... lengthened in spite of disuse . Excluding the feathers , the wings were shorter in seventeen instances , and longer in eight . But as artificial selection has lengthened the wings in some instances , why may it not it not have have ...
Página 68
... lengthened by 20 the bulk of the body.1 Darwin forgot to ask whether allowance must not be made for a frequent , or perhaps general , elongation of the neck and the hinder part of the body , and the relative shortening or the throwing ...
... lengthened by 20 the bulk of the body.1 Darwin forgot to ask whether allowance must not be made for a frequent , or perhaps general , elongation of the neck and the hinder part of the body , and the relative shortening or the throwing ...
Página 70
... lengthened the foot by 13 per cent . in spite of disuse ? SHORTENED LEGS OF RABBITS . In the case of the domestic rabbit Darwin notices that the bones of the legs have ( relatively ) become shorter by an inch and a half . But 1 ...
... lengthened the foot by 13 per cent . in spite of disuse ? SHORTENED LEGS OF RABBITS . In the case of the domestic rabbit Darwin notices that the bones of the legs have ( relatively ) become shorter by an inch and a half . But 1 ...
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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.