| → always 1859 1860 |
| (natural selection) always 1861 1866 |
| represented by natural selection or the survival of the fittest, always 1869 1872 |
|
| ←Subtitle not present 1859 1860 1861 Modes
of
Transition. 1866 1869 1872 |
|
slowly in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further we must suppose that there is a
→always
intently watching each slight
alteration in the transparent layers; and carefully
each
which, under varied circumstances,
in any
or in any degree,
to produce a distincter image. We must suppose each new state of the instrument to be multiplied by the million;
each to be preserved
a better
produced, and then the old ones to be
In living bodies, variation will cause the slight alterations, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. Let this process go on for millions
of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man? →
|
| If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, round which, according to
theory, there has been much extinction. Or again, if we
an organ common to all the members of a
class, for in this latter case the organ must have been
formed at
remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has
|
