88 NATURE TEACHING. 



withered and at length die. Treat in the 

 same way, for comparison, some thick leaves, 

 such as ' dagger ' and notice that these take 

 a very long time before they show any signs of 

 drying up, showing of what use to these 

 plants, which can grow in places where they 

 get very little water, their thick, fleshy leaves 

 are. 



2. 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 experiments 

 teach us that the leaves are continually losing 

 water, but that if we supply sufficient w r ater, 

 either through the stem directly, or indirectly 

 through the roots, the plant will keep fresh. 



3. To prove that leaves actually give off 

 water, take two tumblers partly filled with 

 water, and cover each with a piece of card- 

 board with a hole in the centre. Put through 

 this hole the end of a leaTy shoot 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 



