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Show 2 INTRODUCTION· ·n I think £nd this plan a convenience, fo~, if he does ~ot Wl b' th ' ·lusion or care about the details, he can ea 1ly dou t e cone . tl t t I Y be permitted to say 1a some Pass them over; ye ma · 1 fr of t'1Ie a·l SCUSS.lO nS thus printed deserve attentwn, at east ·om the professed naturalist. . b f l to those who have read notbmg about It may e use u . . . S 1 . ·r I here give a bnef sketch of the whole Natural e ectwn, I . . . I Tl . . b . t d of I·ts bearino- on tlw orJgm of spemes. 1.Is Is su JeC an · b • . • • ·1 t the more d es.n.a bl e, a s it is Impossible m .t he pio. sent W· OJ c do avO.id many al lu sw. ns to questions which will be fully d1scusse in future volumes. From a remote period, in all parts of t~e ':orld, man has b. t c1 any animals and plants to clomesttcatwn or culture. Sll JeC e m d' · f }" f Ma~ has no power of altering tho absolute con Itwns o 1 e; he cannot change the climate of any country ; he . adds no new element to the soil; but he can remove an ammal or pl~nt from one climate or soil to another, and give it food on whiCh it did not subsist in its natural state. It is. an err?r ~~ speak of man "tampering with nature" and causmg vanab1hty. If organic beings had not possessed an inhe1~ent te~dency to vary, man could have done nothing.2 He unmtentwnally exposes his animals and plants to various conditions of life, and variability supervenes, which he cannot even prevent or ~heck. Consider the simple case of a plant which has been cultivated during a long time in its native country, and wh~ch consequently has not been subjected to any change of climate .. It has been protected to a certain extent from the compeb~g roots of plants of other kinds; it bas generally been grown m manured soil, but probably not richer than that of ma~y ~n alluvial fiat; and lastly, it has been exposed to changes m 1ts conditions, being grown sometimes in one district and sometimes in another, in different soils. Under such circumstances, 1 To any one who h1ts attentively rend my ' Origin of Species' this Introduction will be superfluous. As I staterl in that work that I should soon publish tho facts on which the conclusions given in it wore founded, I here beg pcrmissi.on to remark that tl1c grco.t delay in publi shing this first work has boon co.used by continued ill-health. 2 M. Pouchot hos recently (' Plurnlity of Races,' Eng. Translat., 1864, p. 83, &c.) insisted that variation under dome::, tication throws no light on the natural modification of species. I cannot perceive the forco of his argument:!, or, to spenk more accurately, of his asscr· tions to this effect. NATURAL SELECTION. 3 scarcely a plant can be named, though cultivated in the rudest manner, which has not given birth to several varieties. It can hardly be maintained that during the many changes which this earth has undergone, and during the natural migrations of plants f~·om one land or island to another, tenanted by different species, ~bat s~ch pJ~n~s will not often have been suujected to changes m theu c~nclitwns analogous to those whic~ almost inevitably ~au.se. cultivated plants to vary. No doubt man selects varying mcl1 v1dnals, sows their seeds, and again selects their varyinooffi pring. But the initial variation on which man works and ;vithout wh~c_h he ca~ do nothing, is caused by slight ch~nges m the conditions of life, which must often have occurred under natur~. Man, ther~fore,. may be said to have been trying an expenment on a gigantiC scale ; and it is an experiment which nature during the long lapse of time has incessantly tried. Hence it follows that the principles of domestication are important for us. The main result is that organic beings thus treated have varied largely, and the variations have been inherited. This has apparently been one chief cause of the belief long held by some few naturalists that species in a state of nature undergo change. I shall in this volume treat, as fully as my materials permit, tho whole subject of variation under domestication. vVe may thus hope to obtain some light, little though it be, on the causes of variability,-on the laws which govern it, such as the direct action of climate and food, the effects of use and disuse an~ of correla~ion of growtb,-and on the amount of change t~ wh1ch domesticated organisms are liable. We shall learn some~ hing on the laws of inheritance, on the effects of crossing different_ bre~ds, and on that sterility which often supervenes when orgamc bemgs are removed from their natural conditions of life ~nd li~{ew~se when they are too closely interbred. During thi~ ~nveshgatwn we shall see that the principle of Selection is all Important. Although man does not cause variability and cannot eve~ ~revent it, he can select, preserve, and accumulate the var.Iatwns given to him by the band of nature in any way wbwh he chooses; and thus he can certainly produce a great_ resu~t. Selection may be followed eitlter methodically and mtentwnally, or unconsciously and unintentionally. Man B 2 |