PREFACE TO FOURTH EDITION. 



With each edition of this book the author has found it 

 desirable to make certain changes and additions, not only with 

 the object of increasing its usefulness as a text-book for the 

 student, but also for the purpose of making it still more valuable 

 as an aid and guide in practice. In the present edition a number 

 of improvements have been made in the text as well as in the 

 illustrations. The botanical portion of the book has been revised, 

 the author having been fortunate in securing the cooperation of 

 Dr. Theo. Holm, of Brookland, D. C, who has critically gone 

 over certain portions of the morphology and classification of the 

 Angiosperms and re-written a number of the articles. While 

 there are some teachers who naturally prefer their students to 

 have an independent course in botany before taking up pharma- 

 cognosy, the treatment of this subject in this book is such as to 

 be directly applicable to pharmaceutical work, and will be found 

 useful to the student of pharmacy in the college course, as well 

 as of assistance to the pharmacist and analyst who engages in 

 practical pharmacognostical work. 



Up until the present time, the anatomical or histological 

 method has received the sole attention of pharmacognosists. By 

 this method, based for the most part upon the study of tissues, 

 the identity and general quality of drugs and foods are ascer- 

 tained, and the results thus obtained, when taken in conjunction 

 with those of chemical analysis, have been of great value in deter- 

 mining the purity of the products examined. For some years it 

 has seemed to the author important that the pharmacognosist 

 study the active and other constituents of drugs, such as may be 

 obtained in crystalline form from sections, from extractions of 



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