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 155
... difficulty , more especially under changing conditions of life , in the continued preservation of individuals with fuller and fuller flank - membranes , each modification being useful , each being propagated , until by the accumulated ...
... difficulty , more especially under changing conditions of life , in the continued preservation of individuals with fuller and fuller flank - membranes , each modification being useful , each being propagated , until by the accumulated ...
Page 165
... difficulty occur , some of which will be discussed in my future work . One of the gravest is that of neuter insects , which are often very differently constructed from either the males or fertile females ; but this case will be treated ...
... difficulty occur , some of which will be discussed in my future work . One of the gravest is that of neuter insects , which are often very differently constructed from either the males or fertile females ; but this case will be treated ...
Page 203
... difficulty . The great difficulty lies in the working ants differing widely from both the males and the fertile females in structure , as in the shape of the thorax and in being destitute of wings and some- times of eyes , and in ...
... difficulty . The great difficulty lies in the working ants differing widely from both the males and the fertile females in structure , as in the shape of the thorax and in being destitute of wings and some- times of eyes , and in ...
Contents
VARIATION UNDER DOMESTICATION | 6 |
VARIATION UNDER NATURE | 38 |
STRUGGLE FOR EXISTENCE | 52 |
Copyright | |
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Common terms and phrases
accumulated adapted affinities allied species amount analogous ancient animals appear archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distant distinct species divergence domestic doubt eggs embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flower formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important increase in number individuals inhabitants inherited insects instance instincts intercrossing land larvæ less living male mammals manner migration modification modified descendants natural selection naturalists nearly nest occasionally oceanic islands offspring perfect pigeons pistil plants pollen present probably produced progenitor ranked reciprocal crosses remarked resemblance seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder theory tion trees variability variations vary whole widely