2 SUBJECT. 



4. Physiological Botany, besides a knowledge of the 

 external forms of the vegetable body, requires an 

 acquaintance with its internal structure, and the dif- 

 ferent substances therein produced and contained, 

 termed Secretions, with the purposes which such se- 

 cretions answer. 



5. Economical Botany is either empirical or philo- 

 sophical. The former originates in the experience 

 and practical observation of mankind, from one age 

 to another : the latter is deduced from a consideration 

 of certain characters in vegetables ; either indicating 

 peculiar properties ; or pointing out affinities, more 

 or less remote, by which certain known qualities in 

 some plants, are presumed to exist in others. 



6. Before any knowledge of Systematical Botany (3), 

 or the Classification of Plants, can be understood, it 

 is necessary to be acquainted with the various parts 

 of which the Vegetable body consists. These are 

 the Root, Stem, Stalks, Buds, Leaves, Appendages, 

 Flower and Fruit. 



