[Illustration: Plate I. _London, John Van Voorst._] AN ELEMENTARY TEXT-BOOK OF THE MICROSCOPE; INCLUDING A DESCRIPTION OF THE METHODS OF PREPARING AND MOUNTING OBJECTS, ETC. BY J. W. GRIFFITH, M.D., F.L.S., ETC., MEMBER OF THE ROYAL COLLEGE OF PHYSICIANS; CONJOINT AUTHOR OF THE MICROGRAPHIC DICTIONARY, ETC. WITH TWELVE COLOURED PLATES, CONTAINING 451 FIGURES. [Illustration] LONDON: JOHN VAN VOORST, PATERNOSTER ROW. MDCCCLXIV. [_The right of translation is reserved._] PREFACE. The object of this little work is to furnish an elementary course of instruction in the use of the Microscope, and on its application to the examination of the structure of plants and animals. Assuming that the reader has had no previous acquaintance with the Microscope, or with the study of natural history, I have attempted to render the descriptions of the objects as simple as possible. At the same time, the technical terms have been added and explained, in order gradually to render them familiar to the reader, and thus facilitate the future study of larger and more detailed works. The objects figured and described comprise the principal structures and more minute forms of both the vegetable and the animal kingdom, those having been selected which are common and readily procurable. A chapter has been given upon the optical principles on which the action of the instrument depends (which will assist the reader to understand the operation of its constituent parts), including a sketch of the subject of polarized light. The order in which the subjects are treated is scientific, and particular directions have been given for the examination of the objects. The small size of the work has necessitated the exclusion of figurative descriptions, so that it is adapted rather for a worker than a reader; at the same time, the matter forms a course, and must be taken as a whole for the proper comprehension of the subjects. The technical terms used are referred to in the Index, so as to furnish to some extent a glossary of terms; and their derivation is given, to facilitate their recollection. The figures, with very few exceptions, are drawn from nature, and are coloured that the objects may be more easily recognized. The magnifying powers under which they have been drawn are denoted by a small number placed beneath each figure: and the particular attention of the reader is requested to this point; otherwise the whole subject will be utterly confused; so much does the appearance of objects vary under different powers.