2 INTRODUCTION. 



various branches of economic botany, as Forestry, Floricultural, 

 Agricultural, Horticultural, Pharmaceutical and Medical Botany. 

 For the purposes of this work the subject will be treated of 

 mainly under four heads, as follows : 



I. Organography, that branch of structural botany which 



treats of the organs or instruments with which plants do 

 their work, as roots, stems, leaves, parts of flowers, etc., 

 their forms and modifications. 



II. Vegetable Histology, that branch of structural botany 



which treats of the minute or microscopical structure of 

 plants. 



III. Vegetable Physiology, that branch of botanical science 

 that treats of the functions of plants and their organs ; that 

 undertakes to explain how the plant and its various parts 

 perform their work. 



IV. Vegetable Taxonomy. Under this head will be con- 

 sidered the mode of naming and classifying plants, and 

 some brief account of the life histories of the more impor- 

 tant types of vegetable life will be given. 



Some subjects which cannot be strictly included under any 

 of the above heads will also be briefly treated. Due attention 

 will be given to vegetable morphology in the first two parts, and 

 a brief account of the geological succession of plants will be 

 given in separate chapters at the close of Part IV. 



