PART 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 biogi'aphy 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, at length in germination develops 

 into a plant like the parent ; thus completing the cycle of vegetable 

 hfe. A preliminary question, however, presents itself. To under- 

 stand how the plant grows and forms its various parts, and to get 

 a clear idea of what growth is, we must first ascertain what plants 

 are made of. 



CHAPTER I. 



OF THE ELEMENTARY STRUCTURE OF PLANTS. 



Sect. I. Op 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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