WHAT STRUGGLE FOR EXISTENCE IS 



211 



The tree hns appropriated the food 

 that a large area remains hare of 



tion for every inch of its 

 not populated with plants 

 cently been moved. If the 

 his soil frequently', various 

 plants get a foothold, and 

 these plants he calls weeds. 

 Determine how much room 

 an apple tree, or other plant, 

 occupies : then calculate 

 how much space would be 

 required for all the seed- 

 lings of that tree or plant. 

 The (jreafer Hip popnhition 

 "/«>'!/ (it'''<i, fhc less rJi(i)ire 

 hare other phmfs fo </(iin a 

 foothold. When tlie wheat 

 completely covers the 

 ground, as in Fig. 3.") 7, 

 there are no weeds to l)e 

 seen. 



352. Plants of different 

 form and habit may grow 



space, for food 

 and moisture in 

 the soil, for 

 light. We may 

 consider exam- 

 ples in each of 

 these three cate- 

 gories. 



351. If the 

 earth is filled 

 with plants , 

 there must be 

 sharp competi- 

 surface. If any good soil is 

 it is usually because it has re- 

 farmer does not move or till 



and moisture, so 

 vegetation. 



3G0. Tlie clematis elimhing into the sunlight. 

 Compare Fig. 73, 



