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Show 442 DARWINISM CIIAJ'. Much of the mystery of instinct ari. es from the persistent refusal to recognise the agency of imitatio11, ~emory, ob. orv~~tion and reason as often forming pa,rt of It. Yet there 1s am~le evidence that such agency must be t:~ken in~o a.ccou~t. Both Wilson and Leroy state that young birds bmld mfcnor nests to old ones and the la.tter author observes that the best nests arc macle 'by birds whoso young remain lmtgcst in the nest. So mioTation is now well ascertained to be effected by means of ~i. i~n, long flights being made ~n bright moon~ight nio-hts when the birds fly very high, while on cloudy mght!'> th~y fl.v low, and then often lose thei: way. Th~u. a_nd. annually fly out to sea and perish, showmg t~at the mstmct 1 to migrate is imperfect, and is not a good substitute for reason and observation. Ao·ain, much of the perfection of in. tinct is due to the extre~e severity of the election durino· its development, any f<tilure involving destruction. ·Tho chick which cannot break the eo·crsholl tho caterpillar that fails to snf'pend itself properly or to bsbp in ' h . 1 :t sa.fe cocoon, the bee. that lose t en·. way or t ~~t fail to :tore honey, inevitably peri h. So the b1rds that hul to feed and prot~ct their young, or tho butterflies ~hat hy their eggs on the wrong food-plant,_ leave no offspn~g, and the race with impeded instincts perishes. Now, dunng . tho long and very slow course of development of each orgamsm, this rigid election at every step of progress has led ~o tho preservation of every detail of structt~re, faculty, or hab1t tha,t has been necessary for the preservatiOn of the raoc, and has t,hus gradualty built up the various instincts which ~cern so marvellou. to ns, but which ca.n yet be shown to be m m:1,ny cases still imperfect. Here, as everywhere else in nature, :"c find compamti ve, not absolute perfection, with every gradatwn from 'vhat is clea.rly due to imitation or rca.son up to wl_Htt seems to u. perfect instinct-that in which a complex :t<' tJOII is performed without any previous experience or instruction.1 1 \Veismann explains instinct on similar lin es, and gives_ m~ny i_ntcre~ting illustrations (see E ssays on lle1·eclity). He l1 olus "tl:at ~llm ·t1~1ct 1s nll i'l'ly due to the operatioH of natural selection, and has 1ts foundation,_ nol llJ~On inherite<l experiences, but upon variations of the germ." Many lllteres.twg and clifticult case: of instinct are discnsse<l by Darwin in Chapter VIII of the Ori,qin of Species, which should be read in com~ ection with the ~bove re lll ark~. Since this chapter was written my attent10n has been u1rectcd Lo :.\Jr. XIV :FUNDAMENTAL PROBLEMS 443 Concl?.tding Rerncwks. Having now passed in review the more important of the recent objections to, or criticisms of, the theory of natural selection, we have arrived at the conclusion that in no one case have the writers in question been a.ble materially to diminish its importance, or to show that any of the la.ws or forces to which they appeal ca.n act otherwi e tha,n in :trict subordination to it. The direct action of the environment as set forth by Mr. Herbert Spencer, Dr. Cope, and ] )r. Ka.rl Scml)Cr, even if we admit that its effects on the individual are transmitted by inheritance, are so small in compari on with the amount of spontaneous variation of every part of the organism that they must be quite over ·hadowcd by the latter. And if such direct action may, in ·orne ca. c., have initiated certain orga.ns or outgrowths, these must from their very first beginnings have been subject to vari~Ltion and natural selection, and their further development have boon almost wholly due to these ever-present and powerful causes. Francis Galton'. Theo1·y of Heredity (already referred to at p. 417) which was published thirteen years ago as an alternative for Darwin'~ theory of pangenesis. Mr. Galton's theory, although it attracted little attention, appears to me to be substantially the same as that of Professor \VeismaHu. Galton's "stirp" is Weismann's" germ-plasm." Galton supposes ihe sexu:1l elements in the offspring to be directly formed from the residue of the slitp uot used up in the development of the body of the parent- Weismanu's "continuity of the germ-plasm." Galton also draws many of the same conclusions from his theory. He maintains that characters acquired by tl1e individual a· the result of external influcuces cannot be inherited, unless such influences act directly ou the reprorluctive clement -instancing the possiule heredily of alcoholism, because the alcohol permeate. the tissues and may r •nell tl1e sexual elements. He discu ·ses th•~ supposed heredity of efl'eet. · JH'Otlu ce<l hy u e or disnse, anrl explains them much in the sam manner as doefi Weismann. Galton is an anthropologist, a1Hl applies the theory, mainly, to explain the peculiarities of hereditary transmission in man, many of .which pcculiaritie he liscu ·ses and elucidates. Weismann is a biolocri:t, and is mostly concerned with the application of the th ory to explain variation and instinct, anu to the furtlwr development of the theory of evolution. He has worked it out more thoroughly, and has ad luccLl eml>ryological evidence in itH iiupport; hut the views of both writers are substantially the same, antl il1cir tl1eories were arrived at quite imlepemlcntly. 'l'he names of Galton an<l Weiw1aun shoultl therefore be associated as discoverers of what may he considered (if finally established) tl1e most important contribution to tl..te evolution theory since the appearance of the Origin of Species. |