42 DARWINIANA. 



ignorance, and so high our presumption, that we marvel when 

 we hear of the extinction of an organic being ; and as we do not 

 see the cause, we invoke cataclysms to desolate the world, or 

 invent laws on the duration of the forms of life!"— (pp. 72, 73.) 

 " When we look at the plants and bushes clothing an en- 

 tangled bank, we are tempted to attribute their proportional 

 numbers and kinds to what we call chance. But how false a 

 view is this ! Every one has heard that when an American 

 forest is cut down, a very diiferent vegetation springs up ; but 

 it has been observed that the trees now growing on the ancient 

 Indian mounds, in the Southern United States, display the same 

 beautiful diversity and proportion of kinds as in the surround- 

 ing virgin forests. What a struggle between the several kinds 

 of trees must here have gone on during long centuries, each 

 annually scattering its seeds by the thousand; what war be- 

 tween insect and insect — between insects, snails, and other 

 animals, with birds and beasts of prey — all striving to increase, 

 and all feeding on each other or on the trees, or their seeds and 

 seedlings, or on the other plants which first clothed the ground 

 and thus checked the growth of the trees ! Throw up a hand- 

 ful of feathers, and all must fall to the ground according 

 to definite laws ; but how simple is this problem compared 

 to the action and reaction of the innumerable plants and ani- 

 mals which have determined, in the course of centuries, the 

 proportional numbers and kinds of trees now growing on the 

 old Indian ruins ! " — (pp. 74, 75.) 



. For reasons obvious upon reflection, tlie competi- 

 tion is often, if not generally, most severe betwen 

 nearly related species when they are in contact, so 

 that one drives the other before it, as the Hanoverian 

 the old English rat, the small Asiatic cockroach in 

 Russia, its greater congener, etc. And this, when duly 

 considered, explains many curious results ; such, for 

 instance, as the considerable number of different gen- 

 era of plants and animals which are generally found 

 to inhabit any limited area. 



