100 
DARWINISM 
CHAP. 
been able to increase them to a marvellous extent by the 
simple process of always preserving the best varieties to breed 
from. Along with these larger variations others of smaller 
amount occasionally appear, sometimes in external, sometimes 
in internal characters, the very bones of the skeleton often 
changing slightly in form, size, or number; but as these 
secondary characters have been of no use to man, and have 
not been specially selected by him, they have, usually, not 
been developed to any great amount except when they have 
been closely dependent on those external characters which he 
has largely modified. 
As man has considered only utility to himself, or the 
satisfaction of his love of beauty, of novelty, or merely of 
something strange or amusing, the variations he has thus pro¬ 
duced have something of the character of monstrosities. Not 
only are they often of no use to the animals or plants them¬ 
selves, but they are not unfrequently injurious to them. In 
the Tumbler pigeons, for instance, the habit of tumbling is 
sometimes so excessive as to injure or kill the bird ; and many 
of our highly-bred animals have such delicate constitutions 
that they are very liable to disease, while their extreme 
peculiarities of form or structure would often render them 
quite unfit to live in a wild state. In plants, many of our 
double flowers, and some fruits, have lost the power of pro¬ 
ducing seed, and the race can thus be continued only by means 
of cuttings or grafts. This peculiar character of domestic 
productions distinguishes them broadly from wild species and 
varieties, which, as will be seen by and by, are necessarily 
adapted in every part of their organisation to the conditions 
under which they have to live. Their importance for our 
present inquiry depends on their demonstrating the occurrence 
of incessant slight variations in all parts of an organism, with 
the transmission to the offspring of the special characteristics 
of the parents; and also, that all such slight variations are 
capable of being accumulated by selection till they present 
very large and important divergencies from the ancestral 
stock. 
We thus see, that the evidence as to variation afforded 
by animals and plants under domestication strikingly accords 
with that which we have proved to exist in a state of nature. 
