COMPETITION, a term nearly equivalent to the phrase °struggle for existence." Lamarck was the first to point out definitely the fact of competition in the cases of man and the sloth, but it was not until a half-century later that Darwin and Wallace emphasized its far-reach ing importance as a biological agent in evolu tion. Competition may be most strikingly illus trated by a case in which it is entirely absent. The Great Salt Lake of Utah is inhabited by the brine shrimp (Artemia fertilis), which abounds in enormous numbers in the dense briny waters; hundreds may be dipped up in a dish of water and thousands captured by a few sweeps of the tow-net. As the water is so salt that no other animal can live in it except a maggot near shore, it has absolutely not an enemy, and there is no other form to compete with it. Its food is a floating green alga (Poly cystis packardii). It is absolutely harmless and without means of defense, and lays but few eggs; yet its success in point of numbers is beyond all precedent. Another case is that of a fly (Ephydra gracilis)• whose larva abounds at the margin of the same lake. These two cases illustrate how a species may abound in profu sion, though not crowding out other forms, since there are no competitions.
A familiar example of the crowding out of native species by those introduced from foreign countries in the struggle for existence among plants is the ox-eye daisy, which was introduced from Europe, first appearing in Leicester, Mass., in 1740. Many years ago what were once throughout New England green fields of grass became white with its flowers; it drove out even the grasses introduced. On the other hand, in central Europe, throughout France, the Pyrenees and the Alps, as recently ob served, it grows sparsely, never in extensive patches. Other examples are the introduced European injurious insects, the gipsy moth, the scale insects and many others, whose numbers in the Old World are kept within due limits by ichneumon parasites, but which in the United States and Canada, owing to the absence of their natural enemies, breed in unlimited num bers. Another case is that of the Colorado potato-beetle, which spread eastward from com paratively limited tracts in the Rocky Mountain region, and invaded the Eastern States to the shores of the Atlantic. The English sparrow, introduced during a period from 1850 to 1870, has become, owing to the lack of competition, a grievous pest, driving out the native birds.
The periwinkle (Littorinalittotea) of the Euro pean coast; introduced on our shores, about 1855, has multiplied to such an extent that it lives between tide-marks in millions, to one of our native species of the same genus. Such cases as these throw light upon the subject and prove that there is a silent but unceasing strug gle for existence going on over nearly all the earth's surface. Yet in the case of desert plants which grow sparsely, separated by barren spaces, there is, as Henslow has observed, no struggle for existence.
Nowhere is the agency of competition more marked than in human society. In the lower savage races, as in the black race of Africa or the natives of Australia, the scattered tribes have confined their contests to simple raids, and no single people or sub-race has gained marked pre-eminence over another, with the ex ception of the Hottentots and Bushmen, who were largely exterminated by negro tribes from the North. But as we ascend to the higher or white race, to the Semitic, the western Asi atic and European peoples, we have examples of the sudden rise to power and pre-eminence of vast hordes of barbarian peoples under Tamer lane, the Grand Mogul, Attila and other con querors, which have swept over vast territories and crushed the weaker, more peaceful or even civilized but less resistant nations. The rapid ity with which the Arabs overran and still dom inate northern Africa in language, social cus toms and religions; the Mongolian movements eastward into China, and westward to the bor ders of Europe; the successive rise and irre sistible waves of migratory hordes from east ern to northern Europe, throughout prehistoric and historic times; the colonizing and expan sion of the powers of Greece, of Rome, of the Norsemen, Anglo-Saxon, the Spanish, French and German peoples; the success of the white race in the struggle for pre-eminence; the dis appearance of the lower, weaker races, less fa vored intellectually and morally, some of which had become fossilized, or semi-fossilized, and practically inept and unfit,—all these phenomena, which are historic facts, are of a piece with what we witness, though in a less distinct and marked way, in the plant and brute realms. The results are in the long run beneficent, though the injustice, moral degeneration, suffer ing and evils which attend human progress are pitiful and deplorable.