610 NATURE STUDY. 



tically. One leaf stem, the one growing downward, is 

 usually very much elongated to push its leaflets out from 

 under the leaves at the side. The stem of the leaf just 

 opposite this, growing upward, has turned backward to 

 put its leaflets in the position to get the most light, and has 

 remained quite short. 



Perhaps the children can discover how the young horse- 

 chestnut leaves sleep. At night, and sometimes on cold, 

 stormy days, the leaflets droop or hang almost vertically, 

 making each leaf look like a partly closed umbrella. In 

 the morning they are lifted up and spread out like an open 

 umbrella or somewhat like a fan. 



As the younger leaves develop, notice how they fill the 

 spaces between the stems of the older leaves, some leaf 

 stems lengthening, some remaining short, some turning and 

 twisting, so that the younger leaves will not cover or be 

 covered by the older leaves. 



Why do they grow thus ? Keview what was shown in 

 the work on the morning glory about the leaves as starch 

 factories worked by sun-power. All the leaves arrange 

 themselves, in general, so as to get, and allow others to get, 

 the greatest amount of sunlight or of sun-power. 



Watch the stages in the development of the flower clus- 

 ter from the little " bunch of grapes " found in many buds. 

 Note how the leaves are turned back to give the flower 

 room; how the main stem and side stems of the flower 

 cluster lengthen, separating the green balls; how each of 

 these balls grows larger, opens at the tip, showing five 

 (usually) teeth around a white interior; how this white 

 part lengthens and opens; how growing from within it ap- 

 pear several brown knobs, each on a slender stem ; how the 

 mature flower finally appears. The outer green part of each 

 ball or flower bud is the calyx, with five teeth ; the white 

 part is the corolla, separating into five handsome petals ; 



