PDF - Wallace Online
PDF - Wallace Online PDF - Wallace Online
158 NATURAL SELECTION vncurious modifications of plumage, and the capacity of perpetualegg-laying.In pigeons we have a still more remarkableproof of the universality of variation, for it has been atone time or another the fancy of breeders to change the formof every part of these birds, and they have never found therequired variations absent. The form, size, and shape of billand feet have been changed to such a degree as is found onlyin distinct genera of wild birds the number of tail feathers;has been increased, a character which is generally one of themost permanent nature, and is of high importance in theclassification of birds ;and the size, the colour, and the habitshave been also changed to a marvellous extent. In dogs,the degree of modification and the facility with which it iseffected is almost equally apparent. Look at the constantamount of variation in opposite directions that must havebeen going on to develop the poodle and the greyhound fromthe same original stock !Instincts, habits, intelligence, size,speed, form, and colour have always varied, so as to producethe very races which the wants or fancies or passions ofmen may have led them to desire. Whether they wanted abull-dog to torture another animal, a greyhound to catch ahare, or a bloodhound to hunt down their oppressed fellowcreatures,the required variations have always appeared.Now this great mass of facts, of which a mere sketch hasbeen here given, are fully accounted for by the "Law ofVariation " as laid down at the commencement of this paper.Universal variability small in amount, but in every direction,ever fluctuating about a mean condition until made to advancein a given direction by " selection," natural or artificial isthe simple basis for the indefinite modification of the formsof life ; partial, unbalanced, and consequently unstable modificationsbeing produced by man, while those developed underthe unrestrained action of natural laws are at every step selfadjustedto external conditions by the dying out of allunadjusted forms, and are therefore stable and comparativelypermanent. 1 To be consistent in their views, our opponentsmust maintain that every one of the variations that haverendered possible the changes produced by man have been1 That the variations occiirring among wild animals are ample both in numberand amount is proved in Darvrinism, chap. iii.
CREATION BY LAW 159determined at the right time and place by the will of theCreator. Every race produced by the florist or the breeder,the dog or the pigeon fancier, the ratcatcher, the sporting man,or the slave-hunter, must have been provided for by varietiesoccurring when wanted and as these variations were never;withheld, it would prove that the sanction of an all -wiseand all-powerful Being has been given to that which thehighest human minds consider to be trivial, mean, or debasing.This appears to be a complete answer to the theory thatvariation sufficient in amount to be accumulated in a givendirection must be the direct act of the creative mind, but it isalso sufficiently condemned by being so entirely unnecessary.The facility with which man obtains new races depends chieflyupon the number of individuals he can procure to select from.When hundreds of florists or breeders are all aiming at thesame object, the work of change goes on rapidly. But acommon species in nature contains a thousand or a millionfoldmore individuals than any domestic race ;and survivalof the fittest must unerringly preserve all that vary in theright direction, not only in obvious characters but in minutedetails not only in external but in internal organs so that if;the materials are sufficient for the needs of man, there can beno want of them to fulfil the grand purpose of keeping up asupply of modified organisms, exactly adapted to the changedconditions that are always occurring in the inorganic world.Tfte Objectionthat there are Limits to VariationHaving now, I believe, fairly answered the chief objectionsof the Duke of Argyll, I proceed to notice one or two of thoseadduced in an able and argumentative essay on the " Originof Species" in the North British Review for July 1867. Thewriter first attempts to prove that there are strict limits tovariation. When we begin to select variations in any onedirection, the processis comparatively rapid, but after a considerableamount of change has been effected it becomesslower and slower, till at its lengthlimits are reached and nocare in breeding and selection can produce any further advance.The racehorse is chosen as an example. It is admitted that,with any ordinary lot of horses to begin with, careful selectionwould in a few years make a great improvement, and in a
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CREATION BY LAW 159determined at the right time and place by the will of theCreator. Every race produced by the florist or the breeder,the dog or the pigeon fancier, the ratcatcher, the sporting man,or the slave-hunter, must have been provided for by varietiesoccurring when wanted and as these variations were never;withheld, it would prove that the sanction of an all -wiseand all-powerful Being has been given to that which thehighest human minds consider to be trivial, mean, or debasing.This appears to be a complete answer to the theory thatvariation sufficient in amount to be accumulated in a givendirection must be the direct act of the creative mind, but it isalso sufficiently condemned by being so entirely unnecessary.The facility with which man obtains new races depends chieflyupon the number of individuals he can procure to select from.When hundreds of florists or breeders are all aiming at thesame object, the work of change goes on rapidly. But acommon species in nature contains a thousand or a millionfoldmore individuals than any domestic race ;and survivalof the fittest must unerringly preserve all that vary in theright direction, not only in obvious characters but in minutedetails not only in external but in internal organs so that if;the materials are sufficient for the needs of man, there can beno want of them to fulfil the grand purpose of keeping up asupply of modified organisms, exactly adapted to the changedconditions that are always occurring in the inorganic world.Tfte Objectionthat there are Limits to VariationHaving now, I believe, fairly answered the chief objectionsof the Duke of Argyll, I proceed to notice one or two of thoseadduced in an able and argumentative essay on the " Originof Species" in the North British Review for July 1867. Thewriter first attempts to prove that there are strict limits tovariation. When we begin to select variations in any onedirection, the processis comparatively rapid, but after a considerableamount of change has been effected it becomesslower and slower, till at its lengthlimits are reached and nocare in breeding and selection can produce any further advance.The racehorse is chosen as an example. It is admitted that,with any ordinary lot of horses to begin with, careful selectionwould in a few years make a great improvement, and in a
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