"Thirdly, when we enumerate the great changes produced in the species of animals before their maturity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or cultivation; or the changes produced by the mixture of species, as in mules; or the changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs, many of these enormities of shape are propagated and continued as a variety, at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet, and of others without rumps. Mr. Buffon mentions a breed of dogs without tails, which are common at Rome and Naples, which he supposes to have been produced by a custom, long established, of cutting their tails close off. There are many kinds of pigeons admired for their peculiarities which are more or less thus produced and propagated."[154] 6. The means of procuring food has, he says, "diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks to break the harder seeds, as sparrows. Others for the softer kinds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks, and others broad ones to filtrate the water of lakes and to retain aquatic insects. All which seem to have been gradually produced during many generations by the perpetual endeavors of the creature to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purpose required" (p. 238). 7. The third great want among animals is that of security, which seems to have diversified the forms of their bodies and the color of them; these consist in the means of escaping other animals more powerful than themselves.[155] Hence some animals have acquired wings instead of legs, as the smaller birds, for purposes of escape. Others, great length of fin or of membrane, as the flying-fish and the bat. Others have acquired hard or armed shells, as the tortoise and the Echinus marinus (p. 239).