PAET I. 



STRUCTURAL AND PHYSIOLOGICAL BOTANY. 



9. THE principal subjects which belong to this department of 

 Botany may be considered in the most simple and natural order, 

 by tracing, as it were, the biography of the vegetable through the 

 successive stages of its existence, the development of its essen- 

 tial organs, root, stem, and foliage, the various forms they assume, 

 the offices they severally perform, and their combined action in 

 carrying on the processes of vegetable life and growth. Then the 

 ultimate development of the plant in flowering and fructification 

 may be contemplated, the structure and office of the flower, of 

 the fruit, the seed, and the embryo-plant it contains, which, 'after 

 remaining dormant for a time, is at length aroused by the influence 

 of common physical agents, (warmth, air, and moisture conjoined,) 

 and in germination developes into a plant like the parent ; thus 

 completing the cycle of vegetable life. A preliminary question, 

 however, presents itself. To understand how the plant grows and 

 forms its various parts, we must first ascertain what plants are 

 made of. 



CHAPTER I. 



OF THE ELEMENTARY STRUCTURE OF PLANTS. 



SECT. I. OF ORGANIZATION IN GENERAL. 

 10. The Elementary Constitution of Plants, In considering the 



materials of which vegetables are made, it is not necessary at the 

 outset to inquire particularly into their chemical or ultimate com- 

 position, that which they have in common with the mineral world. 



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