CHAPTER IV 
VARIATION OF DOMESTICATED ANIMALS AND 
CULTIVATED PLANTS 
The facts of variation and artificial selection — Proofs of the generality of 
variation — Variations of apples and melons — Variations of flowers — 
Variations of domestic animals — Domestic pigeons — Acclimatisation 
— Circumstances favourable to selection by man — Conditions favour¬ 
able to variation—Concluding remarks. 
Having so fully discussed variation under nature it will be 
unnecessary to devote so much space to domesticated animals 
and cultivated plants, especially as Mr. Darwin has published 
two remarkable volumes on the subject where those who 
desire it may obtain ample information. A general sketch of 
the more important facts will, however, be given, for the 
purpose of showing how closely they correspond with those 
described in the preceding chapter, and also to point out the 
general principles which they illustrate. It will also be 
necessary to explain how these variations have been increased 
and accumulated by artificial selection, since we are thereby 
better enabled to understand the action of natural selection, to 
be discussed in the succeeding chapter. 
The facts of Variation and Artificial Selection. 
Every one knows that in each litter of kittens or of 
puppies no two are alike. Even in the case in which several 
are exactly alike in colours, other differences are always 
perceptible to those who observe them closely. They will 
differ in size, in the proportions of their bodies and limbs, in 
the length or texture of their hairy covering, and notably 
in their disposition. They each possess, too, an individual 
