On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
Dentro del libro
Resultados 6-10 de 83
Página 19
... sometimes ( as I have found with pigeons ) extremely uniform , and everything seems simple enough ; but when these mongrels are crossed one with another for several generations , hardly two of them will be alike , and then the extreme ...
... sometimes ( as I have found with pigeons ) extremely uniform , and everything seems simple enough ; but when these mongrels are crossed one with another for several generations , hardly two of them will be alike , and then the extreme ...
Página 23
... sometimes concur perfectly developed . Moreover , when two birds belonging to two distinct breeds are crossed , neither of which is blue or has any of the above - specified marks , the mongrel offspring are very apt suddenly to acquire ...
... sometimes concur perfectly developed . Moreover , when two birds belonging to two distinct breeds are crossed , neither of which is blue or has any of the above - specified marks , the mongrel offspring are very apt suddenly to acquire ...
Página 29
... sometimes amongst closely allied sub- breeds . And when a cross has been made , the closest selection is far more indispensable even than in ordi- nary cases . If selection consisted merely in separating some very distinct variety , and ...
... sometimes amongst closely allied sub- breeds . And when a cross has been made , the closest selection is far more indispensable even than in ordi- nary cases . If selection consisted merely in separating some very distinct variety , and ...
Página 31
... sometimes cross their dogs with wild canine animals , to improve the breed , and they formerly did so , as is attested by passages in Pliny . The savages in South Africa match their draught cattle by colour , as do some of the Esquimaux ...
... sometimes cross their dogs with wild canine animals , to improve the breed , and they formerly did so , as is attested by passages in Pliny . The savages in South Africa match their draught cattle by colour , as do some of the Esquimaux ...
Página 39
... sometimes see are almost always im- ported from some other country , often from islands . Although I do not doubt that some domestic animals vary less than others , yet the rarity or absence of distinct breeds of the cat , the donkey ...
... sometimes see are almost always im- ported from some other country , often from islands . Although I do not doubt that some domestic animals vary less than others , yet the rarity or absence of distinct breeds of the cat , the donkey ...
Otras ediciones - Ver todas
On the Origin of Species by Means of Natural Selection: or the Preservation ... Charles Darwin Vista previa limitada - 2023 |
Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing land larvæ less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely