In selecting the plants employed as examples of the different groups, such were chosen, as far as possible, as are everywhere common. Of course this was not always possible, as some important forms, _e.g._ the red and brown seaweeds, are necessarily not always readily procurable by all students, but it will be found that the great majority of the forms used, or closely related ones, are within the reach of nearly all students; and such directions are given for collecting and preserving them as will make it possible even for those in the larger cities to supply themselves with the necessary materials. Such directions, too, for the manipulation and examination of specimens are given as will make the book, it is hoped, a laboratory guide as well as a manual of classification. Indeed, it is primarily intended that the book should so serve as a help in the study of the actual specimens. Although much can be done in the study, even of the lowest plants, without microscopic aid other than a hand lens, for a thorough understanding of the structure of any plant a good compound microscope is indispensable, and wherever it is possible the student should be provided with such an instrument, to use this book to the best advantage. As, however, many are not able to have the use of a microscope, the gross anatomy of all the forms described has been carefully treated for the especial benefit of such students. Such portions of the text, as well as the general discussions, are printed in ordinary type, while the minute anatomy, and all points requiring microscopic aid, are discussed in separate paragraphs printed in smaller type. The drawings, with very few exceptions, which are duly credited, were drawn from nature by the author, and nearly all expressly for this work. A list of the most useful books of reference is appended, all of which have been more or less consulted in the preparation of the following pages. The classification adopted is, with slight changes, that given in Goebel's "Outlines of Morphology and Classification"; while, perhaps, not in all respects entirely satisfactory, it seems to represent more nearly than any other our present knowledge of the subject. Certain groups, like the Diatoms and _Characeæ_, are puzzles to the botanist, and at present it is impossible to give them more than a provisional place in the system. If this volume serves to give the student some comprehension of the real aims of botanical science, and its claims to be something more than the "Analysis" of flowers, it will have fulfilled its mission. DOUGLAS H. CAMPBELL. BLOOMINGTON, INDIANA, October, 1889. TABLE OF CONTENTS. PAGE CHAPTER I.--INTRODUCTION 1 Composition of Matter; Biology; Botany; Zoölogy; Departments of Botany; Implements and Reagents; Collecting Specimens.