KELATIOXS ÜF FtJLIAGE-LEAVES TU ABSORBENT ROOTS. 



97 



of the stem are ouly erect for about three-quarters of their length; tlie upper- 

 most third, iuelucling the apex, is bent obliquelj' outwards and downwards. Drops 

 of rain falling on this upper third of a leaf would flow in a centrifugal direction, 

 and do, as a matter of fact, drip down from the apex. Now the leaves in all 



rif^. 14 — Irrigation of Kain-watev. 

 In Aifredla ceniua. - In a iluUeia (^Verbascum phlomoiden). 



these plants are shorter the higher their position upon the stem, so that the total 

 contour of the plant may be described as a slender pyramid. In consequence of 

 this, water dropping from the outward-bent and drooping apices of superior leaves 

 is arrested by that part of an inferior leaf which shelves towards the stem, and is 

 thereby conducted centripetally. Thus all the rain-water received by a plant 

 of this kind at last reaches tlie immediate neighbourhood of the tap-root, and is 



VOL. I. 7 



