Suppose, for instance, that by one of those unaccountable freaks of nature a "spontaneous variation" is produced, as in the case of Seth Wright's sheep; and further suppose that the particular characteristic which distinguished it from the parent stock was favorable to its persistence, by that I mean that the particulars in which it varies from the parent stock will enable the animal, if it be a beast of prey, to secure its food more surely either by an increase of fleetness or stealth, by which it would the more surely run down, or steal upon its victims, and in either case be more sure of its food and hence more secure of existence than the stock from which it came; and if the means of subsistence for these animals were limited, then the variety having the peculiarity of fleetness or stealth would be preserved and perpetuate the peculiarities imparted to it originally by "spontaneous variation," while the original stock would perish. Thus, as evolutionists would say, the fittest would survive in this struggle for existence; and thus the original variation would be preserved and perpetuated and a new variety brought into existence as effectually by this natural means of selection as if man had superintended it for his own benefit. That individuals in organic forms increase in a proportion greater than the provisional means of support is a theory pretty well demonstrated; there is, therefore, a constant struggle for existence in nature, in which the strongest, those best fitted to live and improve their species, prevail. Every variation, therefore, that is favorable to races of plants or animals is seized upon by this principle of natural selection and preserved. Another way of preserving variations is by what our latter-day naturalists call "sexual selection." "Throughout nature," say they, "the male is the wooer; he it is who is armed for fight, and provided with musical organs and ornamental appendages, with which to charm the fair one. The savage and the wild beast alike secure their mate over the mangled form of a vanquished rival. In this manner the more highly favored of either sex are mated, and natural selections made by which better ever producing better, the species in its constant variation is constantly improved."