66 EASY LESSONS IN VEGETABLE BIOLOGY. 



ing carbonic acid gas are able to appropriate the car- 

 bon as food, and return the oxygen to the air. Chap. 

 V, Sec. 9. 



The length of life of leaves varies greatly. In 

 temperate climates the majority of leaves fall off in 

 the autumn, or are deciduous. In the so-called ever- 

 green trees and shrubs they persist through the win- 

 ter, and may even remain several years. 



9. The root, stem, and leaves of a plant constitute 

 its organs of nutrition. Fluid matters are taken up 

 from the soil by the cells of the roots, these are con- 

 veyed to the leaves, and under the influence of air and 

 light are fitted for the purposes of plant life, and for 

 the production of various materials, as starch, gum, 

 sugar, woody matter, gluten, oils, and resins. Chap. 

 V, Sec. 9. 



10. The flower is the organ, or assemblage of or- 

 gans, for the production of the seed. In Endogens 

 and Exogens this structure is conspicuous, and they 

 are hence called flowering plants, to distinguish them 

 from other types. 



Fig. 29 illustrates the general structure and ar- 

 rangement of parts in a flower. The poet Goethe 

 taught that all the various parts of a plant are modi- 

 fications of leaves. Not that they were originally 

 leaves and were transformed, but that they are formed 

 of the same elements, arranged upon the same plan, 

 and follow the same general laws as leaves. The 



