THE WORK OF ROOTS 



87 



about it. Pass the string over the pulley, and tie a bottle 

 or other container on the end. Now put shot or sand into 

 the bottle, a little at a time, until weight enough has been 

 secured to pull the plant from the pot. Weigh both shot 

 and bottle. 



Conclusion. — Why is it that such rivers as the Ohio, 

 Mississippi and others 

 in the Central West 

 carry so much greater 

 quantities of mud at 

 present than in an 

 early day when the 

 land which they drain 

 was in native grasses 

 and timber ? Why do 

 railroad companies 

 and land owners plant 

 willows along the 

 banks of encroaching 

 streams ? From this 

 experiment, would 

 you say that the 

 roots of plants bind 

 the soil quite firmly 

 together ? Why does 

 the government often 

 prohibit the cutting 

 of timber entirely off from hUl and mountain sides on 

 public lands ? 



Fig. 2S. — Pulling up a plant by means 

 of a pulley and weight. 



62. The Root a Storehouse of Food. — Every plant 

 stores in its stems and roots certain amounts of reserve 

 food to be drawn upon in time of iieed. The members of 

 one great class of plants which live two years and are 



