our pigs, dogs, cats, apples, grapes, and other domesticated animals and plants. Fig. 16 shows the domesticated pig that has been derived from the wild boar by Artificial Selection. By this process, such distinct races as the Newfoundland, the Skye Terrier, and the Bulldog have been produced—creatures that have all come from common ancestors, yet so different looking, one from the other, that if they had been found in the wild state, they would not only have been ranked as distinct species, but as even distinct genera. The same method has given us different races of horses, cows, sheep, flowers, grains, etc. The swiftest horses, for instance, are selected to breed together; then the fleetest offspring of these, time after time, until horses are produced whose speed far surpasses that of the originally selected pair from whence they were derived. Darwin has taught us that what man does on a small scale, in a comparatively short time, Nature has been doing on a vast scale for long ages and has thus given rise, from simple forms, to the infinite variety and complexity of animal and plant life, as we behold it on the globe to-day. The selection by man of useful variations in domesticated creatures being appropriately called Man’s Selection, or Artificial Selection; the vastly greater selection by nature of animals and plants with useful variations and on an infinitely grander scale, through inconceivably long ages, is most fittingly called =Natural Selection=. The struggles—of animals, for instance—that necessarily lead to the survival of the fittest, are intensified and made exceedingly acute and severe by the fact that _all animals tend to increase in a geometrical ratio, and by the further fact that the food and place for animals are limited_. In other words, the population of the animals in a given area tends greatly to outrun the means of subsistence. And since animals are constantly varying in many directions and are as plastic in the hands of Nature as clay under the chisel of the modeler, those that possess any useful variations, whether congenital or acquired, that give them any advantages in this great battle of life, will most likely come out of the struggle as victors. [Illustration: FIG. 16.—Wild Boar contrasted with a modern Domesticated Pig. Reproduced from Romanes’ “Darwin, and After Darwin.” By courtesy of The Open Court Publishing Company.]