130 NATURE STUDY 



the newest portion of wood and bark of the stem, and from these 

 again thru the fibers of the veins of the leaf. Now the water and 

 carbonic acid are together in the green part of the leaf. In the 

 presence of the green substance of the leaf called chlorophyll, by 

 means of sunlight, the leaf changes the water and carbonic acid 

 into starch, which is a plant substance from which other plant 

 substances are made by the plant. The starch may be changed 

 to sugar, this in solution may pass over the fibrous pathway in 

 the veins of the leaf and in the stem to serve as nutrition for 

 growing parts or be deposited as sugar or changed to starch again 

 and stored up for future use. 



The importance of the leaves and the meaning of their 

 arrangement on the stem are brought out by these facts. The leaf 

 presents great surface to the air and to the light. They are arranged 

 on the stem in such a way that they are well presented to the 

 light and at the same time shade their fellow leaves very little or 

 none at all. Gather branches of various plants and examine the 

 disposition of the leaves with reference to this fact. Whole plants, 

 such as the geranium, begonia, filarilla, turnip, and in fact any 

 plant will illustrate well how the leaves are arranged on the 

 plant to occupy spaces unoccupied by other leaves, and presenting 

 their upper surfaces to the light without shading those below. 

 This method of arrangement of leaves sometimes throws them 

 into a rosette, compact or loose, sometimes into a mosaic. The live- 

 forever and young filarilla are examples of the former, while cer- 

 tain forms of ivy and of maiden hair ferns of the latter. 



Fruits. 



Lessons with the various common fruits may with profit be 

 given thru August and September. These may be adapted to all 

 grades. The lessons on distribution of seeds have explained the 

 use of the edible parts of many fruits. It may be shown how 

 cultivation and selection have changed fruits to the form most 



