28 THE STORY OF THE PLAxNTS. 



which happened to vary in the right directions 

 would most easily go on living and produce most 

 descendants, while those which happened to vary 

 in the wrong directions would soonest die out and 

 leave fewest descendants. 



Well, the world around us, both of plants and 

 animals, is full of creatures all struggling against 

 one another, and all competing for food and air 

 and sunshine. Moreover, each individual pro- 

 duces (as a rule) a vast number of young; some- 

 times, like the poppy, many thousand seeds on a 

 single flower-stem. Now suppose only ten of 

 those seeds succeed in growing each year. In the 

 first year, that poppy will have produced ten new 

 poppy plants; the year after, each of those ten 

 will have produced ten more, making the total 

 loo; in the third year, they will be i,ooo; in the 

 fourth, 10,000; and so on in the same progression 

 till in a very few years the whole world would 

 simply be full of poppies. And similarly with 

 animals. If every egg in a cod's roe developed 

 into a mature fish, the sea would soon be one solid 

 and compact mass of cod-fish. 



Why doesn't this happen ? Because every 

 other kind is producing seeds or eggs at about 

 the same rate, and every one of them is fighting 

 against the other for its share of light and food 

 and soil and water. The stronger or better- 

 adapted survive, while the weaker or less-adapted 

 go to the wall, and are starved out of existence. 

 At first, to be sure, it sounds odd to talk of a 

 Struggle for Life among plants, which seem too 

 fixed and inert to battle against one another. But 

 they do battle for all that. Each root is striving 

 with all its might to fix itself underground in the 

 best position ; each leaf and stem is struggling 



