120 • Bulletin 174. 



itself, acts in such a manner as to make plant-food already in the 

 soil more available, or which improves its texture, 



21. Is the soil in your garden sour? Try it. 

 See Reading-Lesson No. 3, page 7. 



22. In lohat inaterials can yonhuy jyhosphoric acid for fertilizer 

 jpurposes f 



The most common materials are ibrms of hone. South Carolina 

 rock and Florida rock are ancient deposits of fossihzed bone. Ground 

 fresh bones are sometimes used as a source of phosphoric acid. 



23. In what can you huy potash? 



The common commercial forms of potash are sulfate of potash 

 and muriate of potash. Wood ashes are also a source of this plant- 

 food. 



24. In lohat can you huy nitrogen f 



Sulfate of ammonia and nitrate of soda are common forms. Cot- 

 ton-seed meal, dried blood and tankage are some of tlie organic sources. 



25. A7'e there any home fertilizers^ or cominon farm materials 

 {aside from ham manure)^ in which you can get these elements f 



The plowing under of green-crops, like clover, peas, vetch and 

 the like will furnish nitrogen; wood ashes furnish the only "home 

 supply " of potash ; phosphoric acid must usually be purchased from 

 the dealers. 



NO. 4. HOW THE PLANT GETS ITS FOOD FROM THE SOIL. 



1. Do the rootltairs finally hecome roots, or do they stay on as 

 the main root grows f 



The root-hairs never become roots. As the young rootlets which 

 bear the root hairs enlarge and their tissues become hard, the root- 

 hairs perish. 



2. Are there root- hairs on old roots f 

 No. 



3. On what p>ctrt of the roots are the root-hairs ? 

 On the 3^0 ung, tender rootlets. 



4. Where does the radish plant, ivJnch yon greio i?i moss or cloth, 

 get nourishment for making the first rootliairs f 



This nourishment probably comes from the food-material stored 

 up in the seed. 



