On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for Life |
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Page 228
... crosses be- tween species , and of the hybrids produced from them , is largely governed by their systematic affinity ... reciprocal cross between two species , I mean the case , for instance , of a stallion - horse being first crossed ...
... crosses be- tween species , and of the hybrids produced from them , is largely governed by their systematic affinity ... reciprocal cross between two species , I mean the case , for instance , of a stallion - horse being first crossed ...
Page 229
... reciprocal crosses . Such cases are highly important , for they prove that the capacity in any two species to cross is often completely independent of their systematic affinity , or of any recognisable difference in their whole ...
... reciprocal crosses . Such cases are highly important , for they prove that the capacity in any two species to cross is often completely independent of their systematic affinity , or of any recognisable difference in their whole ...
Page 230
... cross between any two species is not always governed by their systematic affinity or degree of resemblance to each other . This latter state- ment is clearly proved by the difference in the result of reciprocal crosses between the same ...
... cross between any two species is not always governed by their systematic affinity or degree of resemblance to each other . This latter state- ment is clearly proved by the difference in the result of reciprocal crosses between the same ...
Page 231
... crosses and of hybrids is simply incidental or dependent on unknown differences , chiefly in the reproductive systems , of the species which are crossed ; the differences being of so peculiar and limited a nature , that , in reciprocal ...
... crosses and of hybrids is simply incidental or dependent on unknown differences , chiefly in the reproductive systems , of the species which are crossed ; the differences being of so peculiar and limited a nature , that , in reciprocal ...
Page 231
... reciprocal crosses ; or the increased sterility in those hybrids which occasionally and exceptionally resemble ... cross between very distinct individuals of the same species , that is between members of different strains or sub - breeds ...
... reciprocal crosses ; or the increased sterility in those hybrids which occasionally and exceptionally resemble ... cross between very distinct individuals of the same species , that is between members of different strains or sub - breeds ...
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Common terms and phrases
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