94 



YOUNG AND OLD LEAVES. 



of the leaf lies in deep folds, the ribs are brought 

 very near together, and the long, silky hairs on 

 one rib project far over the next, so that the fur- 

 rows between are covered, and the effect of a leaf 

 clothed wholly with silk is produced. There can 



FIG. 19. VERNATION OF THE BEECH. 



I. Bud beginning to expand. 2. Same, more advanced, showing the Leaves between the 

 Scales. 3. Same, still more developed. 4. Back of a Young Beech Leaf, showing 

 the Plicate Folding. 5. A Part of the Same Leaf, showing the Silky Hairs. 6. Upper 

 Surface of Unfolded Leaf ; the Stipules withered and about to fall. 7. Cross-Section 

 of Leaf, perpendicular to the Midrib. 8. Vertical Section, parallel to the Midrib. 

 (" Pflanzenleben.") 



be no doubt about the meaning of these hairs ; they 

 protect the tissue from the rays of the sun until 

 the epidermis is sufficiently thickened. After this 

 thickening has taken place, the folds straighten, 



