On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeCassell, 1909 - 430 páginas |
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Página 27
... vary , and likewise to withstand diverse climates . I do not dispute that these capacities have added largely to the value of most of our domesti- cated productions ; but how could a savage possibly know , when he first tamed an animal ...
... vary , and likewise to withstand diverse climates . I do not dispute that these capacities have added largely to the value of most of our domesti- cated productions ; but how could a savage possibly know , when he first tamed an animal ...
Página 31
... varies in a highly remarkable manner . The caudal and sacral vertebræ vary in number ; as does the num- ber of the ribs , together with their relative breadth and the presence of processes . The size and shape of the apertures in the ...
... varies in a highly remarkable manner . The caudal and sacral vertebræ vary in number ; as does the num- ber of the ribs , together with their relative breadth and the presence of processes . The size and shape of the apertures in the ...
Página 36
... the differences between the several races ; and though they well know that each race varies slightly , for they win their prizes The by selecting such slight differences , yet they ignore all 36 VARIATION UNDER DOMESTICATION.
... the differences between the several races ; and though they well know that each race varies slightly , for they win their prizes The by selecting such slight differences , yet they ignore all 36 VARIATION UNDER DOMESTICATION.
Página 45
... varying , and insensible changes . I must now say a few words on the circumstances , favourable , or the reverse , to man's power of selection . A high degree of variability is obviously favourable , as freely giving the materials for ...
... varying , and insensible changes . I must now say a few words on the circumstances , favourable , or the reverse , to man's power of selection . A high degree of variability is obviously favourable , as freely giving the materials for ...
Página 46
... vary just when gardeners began to attend closely to this plant . No doubt the strawberry had always varied since it was cultivated , but the slight varieties had been neg- lected . As soon , however , as gardeners picked out individual ...
... vary just when gardeners began to attend closely to this plant . No doubt the strawberry had always varied since it was cultivated , but the slight varieties had been neg- lected . As soon , however , as gardeners picked out individual ...
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Términos y frases comunes
accumulated adapted affinities allied species America analogous ancient animals appear archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo endemic existing exterminated extinct extremely facts favourable fertilised fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate larvæ laws less living males mammals manner migration modification modified descendants natural selection naturalists nearly nest occasionally offspring organic organisation origin of species perfect pigeons plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary seeds sexual sexual selection Silurian slight sometimes South America sterility structure struggle successive supposed swimbladder tend theory variability variations varieties vary whole widely