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 

 different substances therein produced and contain- 

 ed, termed Secretions, with the purposes which 

 such secretions 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 con- 

 sideration of certain characters in vegetables ; ei- 

 ther 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, Appen- 

 dages, Flower and Fruit. 



