ORJEC'TIONS TO NATURAL SELECTION. The ob jections now being urged to the special doctrine 14 natural selection are that, (1) to use Herbert Spencer's words, it is 'inadequate': (2) the fa vorable variation may he destroyed by the swamping effects of crossing; (3) natural selec tion is not analogous to artificial selection: na ture is continually eliminating monstrosities, sports, variations, instead of preserving them; they are constantly being bred out in wild plants and animals, or those living muter natural eon Ilitions of existence. Till. otter or :menu sheep, which tinder the breeder's care and watelifillness became a peculiar variety, when permitted to mingle or cross with normal sheep became ex Natural spleetion accounts for the preser vation rather than the origination of new 111' in cipient font's and structures. Eor the causes of variation, it is maintained. wt' 11111.4 look to the ;lethal of the primary factors of organic evo lution. namely to the effects of in light, temperature. heat, moisture, dryness. altitude, food, and so on.
(4) 11 is not necessarily the fittest or most useful struetures or individuals which survive. Carnivorous animals in seizing or swallowing im mense of eggs, embryos. and adult aid vials do not select this or that individual. hut, on the emit vary. old and young. the tit and the mifit, weak ant, strong. are engulfed in the maw of the whale as it swims thron:411 a shoal if minute erustacen : or hundreds of small fishes are indis criminately. without reference to their fitness. swallowed by sharks. 'o with aphides existing in hundreds id thousands on some tree, the birds. like old 'limo of the New l':11g1:11141 Primer, in discrintimifely pick la "all. both great and small." This matter of the survival of the Bluest and the extinction of the unfit has perhaps been somewhat exaggerated, although it is granted that competition nets uneeasingly in the biologi cal envir.aunent.
(5) Darwinians neknowled.w, as does Wallaee in his ParrriniNm, that no one ever saw a spe cies orbdfmted hr 11'1 t111',11 ion \Veismann has frankly affirmed that ''it is really very diflieult to imagine this proves of natural selec tion in its details: and to this day it is impos sible to demonstrate it in any one point" (Con I cm porary keric as, 1S93, p. 322). Vet a number of temperature species. races, or breeds have been experimentally produced by changes of tempera ture. The cases of seasonal dimorphism existing in nature have been exactly paralleled by varia tions in moths and butterflies subjected in the pupa state to cold, or extreme heat ; and season and wet-season as well as summer and winter forms have been produced artificially. be sides other variations supposed to be extinct phylogenctic species,.
(6) The view peculiar to Darwinism is that some individual variation was nursed and pre served. while all the others less favorable died. ;some naturalists claim that the better-founded view is that of Lamarck, that the changes of en vironment simultaneously affected great numbers of individuals in a given region, which became modified by changes of climate, and so on, en massy. This certainly appears to he the ease in local. insular, or geographical races. varieties. or species. What affects one affects all the indi viduals in a given area isolated by mountain harriers or other natural boundaries. Where nat
ural selection appears to act is in the case of protect ive mimicry. The initial causes arc changes in the amount of light, of shade, heat, and other physical agents. yet natural selection appears to be operative in bringing out the won derful eases of mimicry so well known. (Sec \I1 Micnv. ) While therefore the NPO- marekian readily acknowledges that natural selection re sults after new variations lave arisen, there are those who, like the Rev. Alr. Ilenslow. maintain that in the case of seedlings natural selection is not concerned in bringing about the survival of the fittest. adding: ".1 seedling sureires among others solely berallSe it is rigorous." lle claims that as soon as a large number of seedlings ap pear above ground, "natural selection at once steps in. so to say. with the result that all those with too weak a constitution to maintain them selves fail to withstand the struggle for existence and to come to maturity, the stronger plants only proving themselves the best fitted to survive. This process of selection. however, is ipuite in dependent of ant' modifications in morphologiCal strueture, by which 'varieties' or subspecies are alone rt`VOgnized." The tact that the majority of offspring always perish in infancy he calls 'con .t it ut iona I select ion.' (7) Darwin expressly regarded most varia tions as indefinite, chance, fortuitous. spontane ous or promiscuous, 'survival of the fittest.' as L'oni nlcs expressed it, "becoming, the winnowing fan, whose function it is to eliminate all the less fit. in each generation, in order to preserve the good grain. out of which to constitute the next generation. .kinl as this process is supposed to he continuous through sueeessive generations, its action is supposed to be cumulative, till from the eye of a W01111 there is gradually developed the eye of an eagle." ()titer variations Darwin called 'definite.' ln the ehapter of his 'Variation of tnit»ols and Plants ruder nomeglicalion, en titled "Direct and Definite et ion of the External Conditions of Life." he says: "Dy the term definite art iOn, as used in this ehapter, I mean an netion of such a nature that, when many in dividuals of the same variety are exposed during eral generations to any particular change in their conditions of life, all or nearly all the in dividuals are modified in the same manner." This appears to be practically the same view as that which was advanced by Lamarck, and which is called by Eimer Variation as the result of changed conditions is in nearly every casc—per•kuaps four-fifths of all that occur, thus leaving very little scope for the play of chance or fortuitous variations—due to causes of which we are ignorant. Fortuitous variations, in fact, are an almost negligible quan tity. Hence the primary postulate of natural selection that variations arc in general fortuitous is in the nature of an assumption, and not based on observed facts. As the result of recent in vestigation we are coming more and more to the view that variation in general is the result of the action of changed conditions of life, condi tions both physical and biological. and that nat ural selection is not an active agent.