imes is
an event likely to be noticed; but its gradual and scarcely sensible
modification through unconscious selection, {222} and its subsequent
divergence, either in the same or more commonly in distant countries, into
two or more strains, and their gradual conversion into sub-breeds, and
these into well-marked breeds, are events which would rarely be noticed.
The death of a tree, that has attained gigantic dimensions, is recorded;
the slow growth of smaller trees and their increase in number excite no
attention.

In accordance with the belief of the great power of selection, and of the
little direct power of changed conditions of life, except in causing
general variability or plasticity of organisation, it is not surprising
that dovecot-pigeons have remained unaltered from time immemorial; and that
some toy-pigeons, which differ in little else besides colour from the
dovecot-pigeon, have retained the same character for several centuries. For
when one of these toy-pigeons had once become beautifully and symmetrically
coloured,--when, for instance, a Spot had been produced with the crown of
its head, its tail, and tail-coverts of a uniform colour, the rest of the
body being snow-white,--no alteration or improvement would be desired. On
the other hand, it is not surprising that during this same interval of time
our highly-bred pigeons have undergone an astonishing amount of change; for
in regard to them there is no defined limit to the wish of the fancier, and
there is no known limit to the variability of their characters. What is
there to stop the fancier desiring to give to his carrier a longer and
longer beak, or to his tumbler a shorter and shorter beak? nor has the
extreme limit of variability in the beak, if there be any such limit, as
yet been reached. Notwithstanding the great improvement effected within
recent times in the short-faced almond tumbler, Mr. Eaton remarks, "the
field is still as open for fresh competitors as it was one hundred years
ago;" but this is perhaps an exaggerated assertion, for the young of all
highly improved fancy birds are extremely liable to disease and death.

I have heard it objected that the formation of the several domestic races
of the pigeon throws no light on the origin of the wild species of the
Columbidae, because their differences are not of the same nature. The
domestic races for instance do not differ, or differ hardly at all, in the
relative lengths and shapes of the prim