VI 
PREFACE TO SECOND EDITION 
twenty pages on Non-Protoplasmic Cell Contents, the considera- 
tion of Woods, Root Tubercles, the gross structure and histology of 
different types of leaves, broad histologic differences between Mono- 
cotvl and Dicotyl leaves, the histology of floral parts and the his- 
tology of types of fruits and seeds. Chapter VIII on Taxonomy 
has been increased by the addition of 144 pages. Several new fami- 
lies of drug-yielding plants have been added and the treatment of 
family characteristics has in the majority of instances been broad- 
ened. The habitats of drug-yielding plants have been added. In 
that portion of the tables dealing with the names of official drugs, 
those official in the National Formulary have been so designated by 
the abbreviation N. F., to distinguish them from others that may 
occur in the same portion of the table and which are official in the 
Pharmacopoeia. 
In keeping with the increased size of the book, many new illus- 
trations have been introduced. A number of these are original draw- 
ings, photographs and photomicrographs. To the authors of other 
works from which cuts were borrowed, the writer’s thanks are due. 
The writer in conclusion desires to thank Dr. John M. Macfarlane, 
head of the Botanical Department of the University of Pennsylvania, 
for valuable suggestions during the preparation of portions of the 
text. 
H. W. Y. 
