rnE LEAF 71 



sky and earth like normal leaf blades, or to right and left. Do they 

 belong to the class of leaf formations or tliat of modified stems ? They 

 represent how much stem? leaf? 



Draw the body in qnestion, with enough of the stem to show the 

 position. 



X. THE LEAP 



103. We have seen that as soon as the seedling comes 

 np the cotyledons ave spread, and the leaves of the plumule, 

 if already formed, are shortly unfolded to catch the sun- 

 light ; and that even within the iirst day after emerging 

 from the soil, the leaves of the seedling take on a deep 

 green color, the sign of healthy activity in p)lants. In 

 huds, leaves liave been studied in tlieir early stages and 

 in the resting condition ; and it has heen seen liovif both 

 above-ground and beneatli-ground leaves are prepared long 

 before tliey are needed as foliage, and are held in reserve in 

 order that upon the return of warm weather in the spring 

 the plants may begin witli little delay to make new growth. 

 The varied developments of tlie stem, as rigid shafts of 

 great lieight, as twining or as climbing stems, have the 

 object of displaying the leaves to the liglit to the best 

 advantage. All tliesc tlungs point to the activity of the 

 leaf in carrying on vegetaljle life. 



THE OFFICE OF THE LEAF 



104. The leaf is doubly active in nourishing the plant. 

 In the first place, it absorbs, like the root ; only, while 

 the root takes up liquids and solutions, the leaf takes in 

 gases. Secondly, the leaf is especially tlie organ in which 

 solar energy is caught and stored by the formation of 

 certain substances. These substances are tlie food of the 

 plant, — using now the word food in the same sense in 

 wliich it was used in the cliapter on seeds and seedlings. 

 The food formed in the leaf contains energy to be used 

 in growth and motion. 



105. The food provided for the seedling by the mother 

 plant is of small amount. Very soon after germination 



