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 those who 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 



