STATUS OF DARWINISM AT TIIE PRESENT DAY.
Such arc the views of Darwin, as published in his Origin of Species. Although he pushed the special form of evolution to what one would sup pose to be its furthest limits, yet as We have seen he somewhat modified his views late• in life. The views of probably a large proportion of the moderate Darwinians at the present time have been expregsed in a broad and candid way by Romanes, an able and eareful commentator and expounder of the doctrine of natural selection. In his Darwin aml After (1592). the most clear and readable of the doctrine, the doctrine is thus stated. All plants and animals are perpetually engaged in the strug gle for existence. This strife consists in the fact that in every generation of every species a great many more individuals are born than can pos sibly survive. Now nature "selects the best indi• victuals out of each generation to live." "And not only so, hut as these favored nuctwnguaIs transmit their favorable to their off spring, according to the fixed laws of heredity, it further follows that the individuals composing each successive generation have a general tend eney to lie better suited to their surroundings than were their forefathers. . . . And this follows not merely because in every generation it is only the 'flower of tile Clock' that is allowed to breed. but also because, if in any generations some new and beneficial qualities happen to arise as slight variations from the ancestral type. they
will (other things permitting) be seized upon by natural seleetion. and, being transmitted by heredity to subsequent generations, will he added to the previously existing type." At the present da? an increasing number of evolutionists do not regard natural selection as an active cause, hut lather as the result of the action of a number of (alter agents, comprising the Lainarcl:ian factor,: of change of environment, use, disuse, isolation, and so on. Undonbtedly, as the result of conq)c tifion. animals have been driven to migrate, to adopt IIVN1 habits. and thus to undergo modifica tion. Al any agree with belt spencer as to the inadequacy of natural selection to account for the origination of new forms. From probably a third to nearly one-half of the species of plants and animals now existing are climatic, local forms, resulting from the direct action of elianges in the conditions of life, such as climate, soil, food, and the like. The great number of species of parasitic animals are the result of the young adopting a fixed or a more or less sta tionary mode of life. Natural selection is in operative in the ease of blind or eyeless cave and deep-sea animals.