e class, between parts of
the same individual--EMBRYOLOGY, laws of, explained by variations not
supervening at an early age, and being inherited at a corresponding
age--RUDIMENTARY ORGANS; their origin explained--Summary.

From the first dawn of life, all organic beings are found to resemble each
other in descending degrees, so that they can be classed in groups under
groups. This classification is evidently not arbitrary like the grouping of
the stars in constellations. The existence of groups would have been of
simple signification, if one group had been exclusively fitted to inhabit
the land, and another the water; one to feed on flesh, another on vegetable
matter, and so on; but the case is widely different in nature; for it is
notorious how commonly members of even the same sub-group have different
habits. In our second and fourth chapters, on Variation and on Natural
Selection, I have attempted to show that it is the widely ranging, the much
diffused and common, that is the dominant species belonging to the larger
genera, which vary most. The varieties, or incipient species, thus produced
ultimately become converted, as I believe, into new and distinct species;
and these, on the principle of inheritance, tend to produce other new and
dominant {412} species. Consequently the groups which are now large, and
which generally include many dominant species, tend to go on increasing
indefinitely in size. I further attempted to show that from the varying
descendants of each species trying to occupy as many and as different
places as possible in the economy of nature, there is a constant tendency
in their characters to diverge. This conclusion was supported by looking at
the great diversity of the forms of life which, in any small area, come
into the closest competition, and by looking to certain facts in
naturalisation.

I attempted also to show that there is a constant tendency in the forms
which are increasing in number and diverging in character, to supplant and
exterminate the less divergent, the less improved, and preceding forms. I
request the reader to turn to the diagram illustrating the action, as
formerly explained, of these several principles; and he will see that the
inevitable result is that the modified descendants proceeding from one
progenitor become broken up into groups subordinate to groups. In the
diagram each letter on the uppermost line may represent a genus including
several species; and