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successively occupy the territories now inhabited by their 

 predecessors. 



This law of life is of universal application, and is the final 

 expression of that deadly struggle to which all life is committed. 

 It is Nature's law that the weak must give place to the 

 strong, for the latest developed and most vigorous species 

 will always prevail against the older and more primitive forms, 

 and, bearing this in mind, we must regard as illogical and 

 untenable any theory or belief that the primitive species or 

 groups can extend their range to the disadvantage or detriment 

 of the superior and stronger forms of life. As reasonably 

 might we apprehend that the lower and more degraded races qf 

 mankind could invade the European region and overcome the 

 Europeans. 



Speaking broadly, there has thus been no interchange of life 

 between different regions, and no probability or even possi- 

 bility of any permanent invasion or occupation of the Palasarctic, 

 and more especially the mid-European region, by Arctic, Asiatic, 

 African, or American forms of life, all of which are confessedly 

 inferior to the inhabitants of Europe, and could not long survive 

 in competition with them if brought here, as the species now 

 inhabiting all these more primitive countries are members of 

 genera or families which probably emanated from the European 

 region and have mostly been expelled therefrom by the species 

 afterwards evolved there. 



Thus Australia, New Zealand, South America, or any other 

 archaic region, would assuredly not have remained so primitive 

 in their fauna and flora if these countries had possessed any 

 degree of evolutionary activity, or if the more or less complete 

 isolation from which they have suffered had not so efiectually 

 shut out the superior life which was being evolved in Western 

 Palœarctica, for then the Marsupial and other ancient forms 

 of life would have long ago ceased to exist or have lost their 

 local dominancy and been compelled to adopt nocturnal, sub- 

 terranean, or other modes of life, take refuge in forest recesses, 

 ascend lofty mountains, or become isolated in desolate and 

 uninviting districts, so that the severity of their struggle for 

 life with more dominant species must be greatly mitigated or 

 temporarily cease : for it is only by such methods that some 



