I should not scruple to assert that were the breeding to continue for ever, the head and legs of these sheep would never be so small as the head and legs of a rat.
It cannot be true, therefore, that among animals, some of the offspring will possess the desirable qualities of the parents in a greater degree, or that animals are indefinitely perfectible.
The progress of a wild plant to a beautiful garden flower is perhaps more marked and striking than anything that takes place among animals, yet even here it would be the height of absurdity to assert that the progress was unlimited or indefinite.
One of the most obvious features of the improvement is the increase of size.

The flower has grown gradually larger by cultivation.

If the progress were really unlimited it might be increased ad infinitum, but this is so gross an absurdity that we may be quite sure that among plants as well as among animals there is a limit to improvement, though we do not exactly know where it is.

It is probable that the gardeners who contend for flower prizes have often applied stronger dressing without success.

At the same time it would be highly presumptuous in any man to say that he had seen the finest carnation or anemone that could ever be made to grow.