STRUCTURE AND PHYSIOLOGY OF PLANTS 9 



"Wrap some black or dark paper around the body of the bottle 

 to exclude the light. Roots seek darkness. Keep the soil 

 moist and in a warm room for a week or so. The growth of 

 the young roots will then have reached the inside surface 

 of the glass. Notice their very fine, plush-like appearance 

 (Figs. 2a and 6). Notice also which grow in length faster 

 during the first two weeks, the roots or the tops of the young 

 corn plants. 



FIG. 2o. Corn grown in a bottle of soil. The dark paper around it excludes 

 the light, so the roots may be studied by removing the paper. 



FIG. 2&. Corn grown as in Fig. 2a, showing fibrous roots and root-hairs for 

 absorbing moisture. 



EXERCISE. Root-hairs on Seedlings. Sprout some seeds 

 of squash or beans in folds of moist blotters between two 

 plates until the roots are two or three inches long. Examine 

 for root-hairs on these by holding them against a dark cloth 

 or paper. 



Stems of plants have several uses: They support the 

 leaves and hold them up to the air and light. They serve as 

 storehouses for the saving of starch, sugar, and other forms 

 of nourishment for the future use of the plant. They are 

 the channels of circulation of plant sap and the transfer 

 of plant food from root to leaf and from leaf to root. 



