| → insect; 1869 |
| insect. 1859 1860 1861 1866 |
| insect; and these modifications may affect, through correlation, the structure of the adult. 1872 |
|
| → and these modifications may 1869 |
| These modifications will no doubt 1859 1860 1861 |
| These modifications will probably 1866 |
|
| → OMIT 1869 |
| the laws of 1859 1860 1861 1866 |
|
| → may 1869 1872 |
| will probably often 1859 1860 1861 1866 |
|
| → they 1869 1872 |
| modifications consequent on other modifications at a different period of life, 1859 1860 1861 1866 |
|
| → OMIT 1869 1872 |
| in the least degree 1859 1860 1861 1866 |
|
| → species would become extinct. 1869 1872 |
| would cause the extinction of the species. 1859 1860 1861 1866 |
|
| → whole community; if this in consequence 1869 |
| community; if each in consequence 1859 1860 1861 1866 |
| whole community; if the community 1872 |
|
|
of poultry, and in the colour of the down of their chickens; in the horns of our sheep and cattle when nearly adult;— so in a state of nature, natural selection will be enabled to act on and modify organic beings at any age, by the accumulation of
at that age, and by their inheritance at a corresponding age. If it profit a plant to have its seeds more and more widely disseminated by the wind, I can see no greater difficulty in this being effected through natural selection, than in the cotton-planter increasing and improving by selection the down in the pods on his
Natural selection may modify and adapt the larva of an insect to a score of contingencies, wholly different from those which concern the mature
→insect;
→and these modifications may
affect, through
→OMIT
correlation, the structure of the
So, conversely, modifications in the adult
→may
affect the structure of the larva; but in all cases natural selection will ensure that
→they
shall not be
→OMIT
injurious: for if they
so,
→species would become extinct.
|
|
| Natural selection will modify the structure of the young in relation to the parent, and of the parent in relation to the young. In social animals it will adapt the structure of each individual for the benefit of the
→whole community; if this in consequence
profits by the selected change. What natural selection cannot do, is to modify the structure of one species, without giving it any advantage, for the good of another species; and though statements to this effect may be found in works of natural history, I cannot find one case which will bear investigation. A structure used only once in an
life, if of high importance to it, might be modified to any extent by natural selection; for instance, the great jaws possessed by certain insects,
|
