PREFACE. 



Owing to the role played by vegetable substances in the treat- 

 ment of disease, pharmacognosy takes rank as one of the most 

 important divisions of applied botany. It is generally understood 

 to treat of the external characters, gross structure, histology," and 

 chemical constituents of the plant parts used in medicine. In 

 a broader sense it also implies the study of plants themselves, of 

 systematic botany, and of plant chemistry (phyto-chemistry). 

 Furthermore, when the factors which influence the formation of 

 the active principles in plants are taken into consideration, the 

 subject is seen to have a relation to plant physiology on the one 

 hand and to plant culture on the other. 



This work is divided into three parts. Part I comprises five 

 chapters, and is devoted to a consideration of the distinguishing 

 characters of the main groups of plants, from the lowest to the 

 highest; (2) the anatomy or outer structure of the Angiosperms 

 (or so-called Flowering Plants) ; (3) the inner structure or 

 histology of the higher plants, including the cell-contents ; (4) 

 a classification of the Angiosperms yielding vegetable drUgs and 

 other useful products, together with concise descriptions of the 

 plants, as also of the non-official drugs derived from them, and 

 (5) the subject of the cultivation of medicinal plants. 



Part II comprises two chapters, one devoted to the crude 

 drugs official in the United States Pharmacopoeia, including a 

 few non-official drugs, and another which treats of the subject 

 of powdered drugs and foods. The latter is designed not only 

 for the use of students but also to furnish assistance to food and 

 drug analysts in identifying and estimating the quality of vege- 

 table powders, and includes a descriptioh of the distinguishing 

 histological elements of over two hundred food, spice and drug 

 products, together with directions for making examinations of 

 materials of this kind. 



In Part III are given the various classes of reagents, together 

 with the technique involved in sectioning and the mounting of 

 specimens. In addition various tests are given in connection with 

 dififerent subjects in other parts of the book. ."A 



