These examples suffice to show that the form and functions of a living organism, as well as its mental faculties, are derived not only from the most recent direct ancestors of this organism, but that they partly mount much higher in the genealogical tree. Our coccyx is a vestige of the tail of animals. It is from them also that we have inherited anger and jealousy, sexual appetites, fear, cunning, etc. As long as they remain in use, the oldest inherited characters normally remain the most tenacious and are preserved the longest. When they cease to be utilized, or become useless, they still remain for a long time as rudiments before finally disappearing; for instance the vermiform appendix of the intestine and the pineal gland of the brain. These rudiments often persist for still a longer time in the embryo, as we have seen in the case of the ancestral teeth of the embryo whales. We also meet with the stumps of wings in the chrysalis of certain ants (_Anergates_), the males of which have lost their wings. =Natural Selection.=--The artificial selection practiced by gardeners and cattle breeders led _Darwin_ to his hypothesis of natural selection by the struggle for existence. Confirmed in his idea by the observation of tropical nature, _Darwin_ thought he could explain the origin of living beings by natural selection. It is this hypothesis which is properly called _Darwinism_. But the name Darwinism has also been given to evolution as a whole, which has been the cause of endless confusion. All the mystic and narrow-minded, full of biblical prejudice, naturally profit by this confusion to attack the facts of evolution and science itself. =The Struggle for Existence.=--The struggle for existence and natural selection are absolutely positive facts, which can be constantly verified by the observation of living nature as it is presented to us. All living beings eat one another or at any rate struggle against each other, plants as well as animals; and, apart from air and water, animals are almost entirely nourished by plants and other animals. It is obvious that in this perpetual struggle the less adapted and the less armed--and by arms we include the powers of reproduction, resistance to diseases and to cold, etc.--disappear, while the better adapted and the better armed persist. I confess I cannot understand the detractors of _Darwin_ who are blind in face of these facts and hypnotized by certain conventional suggestions.