PDF - Wallace Online

18 NATURAL SELECTION iThere must be a cause for them ; they must be the necessaryresults of some greatnatural law. Now, if, as it has beenendeavoured to be shown, the great law which has regulatedthe peopling of the earth with animal and vegetable life is,that every change shall be gradual that no new;creatureshall be formed widely differing from anything before existingthat in; this, as in everything else in nature, there shallbe gradation and harmony, then these rudimentary organsare necessary, and are an essential part of the system ofnature. Ere the higher Vertebrata were formed, for instance,many steps were required, and many organs had to undergomodifications from the rudimental condition in which onlythey had as yet existed. We still see remaining an antitypalsketch of a wing adapted for flight in the scaly flapper of thepenguin, and limbs first concealed beneath the skin, and thenweakly protruding from it, were the necessary gradationsbefore others should be formed fully adapted for locomotion. 1Many more of these modifications should we behold, and morecomplete series of them, had we a view of all the forms whichhave ceased to live. The great gaps that exist between fishes,reptiles, birds, and mammals would then, no doubt, besoftened down by intermediate groups, and the whole organicworld would be seen to be an unbroken and harmonioussystem.ConclusionIt has now been shown, though most briefly and imperfectly,how the law that " Every species has come into existencecoincident both in time and space with a pre-existing closely alliedspecies" connects together and renders intelligible a vastnumber of independent and hitherto unexplained facts. Thenatural system of arrangement of organic beings, their geographicaldistribution, their geological sequence, the phenomenaof representative and substituted groups in all theirmodifications, and the most singular peculiarities of anatomicalstructure, are all explained and illustrated by it, in perfectaccordance with the vast mass of facts which the researches ofmodern naturalists have brought together, and, it is believed,1The theory of Natural Selection has now taught us that these are not thesteps by which limbs have been formed ;and that most rudimentary organshave been produced by abortion, owing to disuse, as explained by Mr. Darwin.