434 Life and Immortality. 



necessity of a large stock of the same species for its pres- 

 ervation, for in such cases we may believe that a plant could 

 only exist where the conditions of its life were so favorable 

 that many could exist together and thus save the species from 

 extinction. 



Complex and varied are the checks and relations between 

 organic beings which have to struggle together in the same 

 country. In the case of every species, many different 

 checks, some very complicated and unintelligible to man at 

 present, acting at different periods of life, and during different 

 seasons or years, come into play, some one check or some 

 few being generally the most powerful, but all concurring 

 in determining the average number or even the existence 

 of the species. Widely-different checks sometimes act on 

 the same species in different districts. Looking at the 

 plants and bushes that clothe an entangled bank, we are 

 tempted to ascribe their proportional numbers and kinds to 

 what we call chance. But this is a very false view to take 

 of the matter. Chance has no part in such things. They 

 follow in obedience to laws of which we know comparatively 

 little. When an American forest is cut down a very different 

 vegetation springs up. Ancient Indian ruins have been 

 observed in the southern parts of the United States, which 

 must in former times have been cleared of trees, but which 

 now display the same beautiful diversity and proportion of 

 kinds as are now found in the surrounding virgin forest. 

 What a struggle must have gone on during long centuries 

 between the several kinds of trees, each annually scattering 

 its seeds by the thousand, and what a war between insect 

 and insect, and between insects, snails and other animals 

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

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

 seedlings, or on the other plants which once clothed the soil, 

 and thus checked the growth of the trees ! It is easier to 

 account for the fall of an apple from a tree, or the descent 

 of a stone to the earth when hurled into the air, than to 



