CHAPTER II. 

 ROOTS. 



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1. The Roots serve the double purpose of fixing the plants 

 securely in the soil, and of absorbing the nourishment which 

 is largely contained in solution in the soil-water. They branch 

 irregularly, and subdivide repeatedly, finally ending in a mul- 

 titude of very small rootlets. A portion, near the tip only, of 

 each rootlet is thickly covered with very small hairs. These 

 absorb the soil-water. As the rootlet elongates new hairs are 

 produced, the older ones quickly dying and leaving no scar. 

 Both the rootlets and hairs are most abundantly developed 

 in fertile soils that contain a moderate amount of moisture. 

 The hairs are not developed at all when the roots grow in 

 water. The older roots and older portions of the rootlets are 

 destitute of hairs and they do not perform the function of 

 absorption, or to an inconsiderable extent only. In the 

 resting or dormant (winter) stage of plants, when no new 

 roots nor root-hairs are being developed, but little absorption 

 takes place. At this time transplanting can be done with less 

 injury than if done during the growing season. 



Numerous plants should be pulled or dug up and their roots examined. 

 The germinator previously described, if provided early enough, will furnish 

 a variety of examples. Also make a root-cage by tying together two panes 

 of glass, kept one-fourth inch apart by narrow strips of wood placed near the 

 edges on three sides. Fill the space between the panes of glass with fine 

 sand or soil and plant a seed of Sunflower or Corn (or other plants) near the 

 upper open edge ; supply moisture, keep at a proper temperature, and watch 

 the root-development from day to day. Make sketches and notes of the 

 observations. 



2. The Root-hairs (called rhizoids) apply themselves very 

 closely to the minute particles of which the soil is composed, 



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