THE LEAF 



87 



essential to use the leaves mentioned above, any leaf with 

 a fairly long leaf-stalk will do equally well, the cork 

 being split as before and clipped around the leaf-stalk, 

 fitted into a slight groove made in one of the half corks 

 if necessary. 



Take a plant growing in a pot, and do not water it 

 for a day or two. The 

 leaves droop exactly as 

 those of the cuttings left 

 lying on the table. Soak 

 the pot with water, and the 

 plant revives. These ex- 

 periments teach us that 

 the leaves are continually 

 losing water, but that if 

 we supply sufficient water, 

 either through the stem 

 directly, or indirectly 

 through the roots, the 

 plant will keep fresh. 



Take two tumblers 



partly filled with water, FIG. 9. Second experiment to show 



that water is given off by leaves. 



and cover each with a 



piece of cardboard with a small hole in the centre (see 

 Fig. 9). Put through this hole the end of a leafy shoot 

 for instance, of dead-nettle or groundsel and arrange 

 matters so that the cut end of the stem dips under 

 the water. Block the hole with wax or other material. 

 Cover each of the shoots with a second tumbler, turned 

 upside down and resting on the cardboard covering the 

 first Place one set in the light in a window, and the 



