12 



Nature- Study Agriculture 



leaves come above ground, the roots have begun to form 

 and are searching in the soil for nourishment to take the 



Pollen Tube 



Pollen grain 

 nucleus 



The two 

 nuclei! 

 have grown 



g\ together. 



Ovule nucleus 



FIG. ii. How fertilization takes place. 



place of that stored in the seed, for the scanty supply 

 will soon be exhausted. (Exp. 12.) Rich soil is not 

 necessary to start seeds all they need at first is mois- 

 ture, warmth, and air. (Exp. 13.) 



Experiments and Observations 



1. Make a collection of roots of various forms: fibrous; 

 branching; with taproot; with store of nourishment; etc. Try 

 to tell why each form of root is advantageous to a different kind 

 of plant. 



2. Cut off near the ground some vigorous plant and, by wrap- 

 ping with adhesive tape, fasten a small glass tube to the cut stump. 

 The rise of sap in the tube shows that water must enter the plant 

 through the roots. 



3. Place radish seeds between two pieces of wet blotting 

 paper. Cover, and at one end let the blotter hang in water to 

 keep them from becoming too dry. Root hairs will form in a 

 few days (Fig. 4). 



