THE DARWINIAN THEORY. 



91 



Darwin states there is little doubt that the stock of partridges, 

 grouse, and hares on any large estate depends chiefly on the 

 destruction of vermin, though others might also suggest that 

 the amount of protection is important. Thus the Malthusian 

 doctrine — that population, if left to itself, increases at some- 

 thing like a geometrical progression, while the means of susten- 

 ance from the fertility of the land and bringing in waste only 

 increases at something like an arithmetical progression — suits 

 well with the Darwinian theory, and, like it, requires the agency 

 of checks. The lucky and the strong must prevail, or multiply 

 and vary, while the weaker and ill-favoured perish. 



[No more striking instance of the feature alluded to by 

 Darwin could be mentioned than the introduction of rabbits 

 into Australia. The same may be said of the Voles (Arvicola 

 agrestis) of our own country, which occasionally appear in in- 

 credible numbers in woods, and do great damage to trees and 

 shrubs both above and below ground. The plan of sheltering 

 young trees and shrubs in exposed situations by permitting the 

 grass to grow around them prevents the owls and hawks from 

 preying so readily on the Voles, and thus aids in keeping up 

 their numbers.] 



His opponents, however, instance the fact that according to 

 the rate of modification experimentally proved in regard to 

 domestic pigeons, we ought to find evidence of progressive in- 

 crease, for example, in the combative qualities of the antlers in 

 those deer that for centuries have fought and bred in the moun- 

 tain wilds of Scotland. Such is found not to be the case on 

 comparing modern antlers with the most ancient ones from sub- 

 merged forest lands. Cuvier, too, proved that no change of 

 specific characters had occurred in the ibis, cat, and crocodile 

 found in the tombs of Egypt, and ranging back three, four, or 

 five thousand years ago. Moreover, Agassiz adduces the evi- 

 dence that the coral polyps engaged at present in constructing 

 the reefs on the coast of Florida have been engaged there for 

 thirty thousand years at least, and all this time no change has 

 ensued in their specific characters. Darwin gets over this diffi- 

 culty by saying that it is not necessary that every species should 

 vary, but only some, and that only occasionally. 



There are others, again, who object to the notion that any 



