MANOAI, Olf NAfURB STUDY. 9? 



make tlie soil ricli and tlius nourisli the plant. 

 Even their bodies when they die decompose and 

 become food for plants. 



Summary, 



What plants do for the animals. 



1. Plants furnish ready-made oxygen for ani- 

 mals to breathe. 



2. Plants gather the elements out of the ground 

 and make them over into food for the animals' sub- 

 sistence. 



3. Plants hold back the moisture on sloping 

 lands and thus prevent arid wastes. By this means 

 gushing springs, to slake the thirst of animals, 

 burst out at the foot of the hills and bluffs. 



4. Plants furnish protection from storm and 

 scorching sun. 



How the animals repay the plants. 



1. Animals yield up carbon dioxide as food for 

 the plant. 



2. Animals drain the ground and thus make 

 the soil in proper condition for the plants. 



3. Animals (earth-worms) lead the water of 

 heavy rain in dry time through the soil to an 

 underground outlet, rather than permit it to rush 

 away in one general flood and thus do the soil no 

 good. 



4. Animals assist in fertilization. 



