Seite - 220 - in The Origin of Species

220 ORIGIN OF SPECIES arrange his genealogical tree" in such a manner that all the descendants have longer lives than their progenitors! Can- not our critic conceive that a biennial plant or one of the lower animals might range into a cold climate and perish there every winter; and yet, owing to advantages gained through natural selection, survive from year to year, by means of its seeds or ova? Mr. E. Ray Lankester has re- cently discussed this subject, and he concludes, as far as its extreme complexity allows him to form a judgment, that longevity is generally related to the standard of each species in the scale of organisation, as well as to the amount of ex- penditure in reproduction and in general activity. And these conditions have, it is probable, been largely determined through natural selection. It has been argued that, as none of the animals and plants of Egypt, of which we know anything, have changed during the last three or four thousand years, so probably have none in any part of the world. But, as Mr. G. H. Lewes has re- marked, this line of argument proves too much, for the ancient domestic races figured on the Egyptian monuments, or embalmed, are closely similar or even identical with those now living; yet all naturalists admit that such races have been produced through the modification of their original types. The many animals which have remained unchanged since the commencement of the glacial period, would have been an incomparably stronger case, for these have been exposed to great changes of climate and have migrated over great distances; whereas, in Egypt, during the last several thousand years, the conditions of life, as far as we know, have remained absolutely uniform. The fact of little or no modifi- cation having been effected since the glacial period would have been of some avail against thosewho believe in an innate and necessary law of development, but is powerless against the doctrine of natural selection or the survival of the fittest, which implies that when variations or individual differences of a beneficial nature happen to arise, these will be preserved; but this will be effected only under certain favourable cir- cumstances. The celebrated palaeontologist, Bronn, at the close of hisi German translation of this work, asks, how, on the principle i