PREFACE TO THE FOURTH EDITION.

THE fourth edition of this book has been carefully revised and several errors, to which attention has been kindly called, corrected. A few methods have been omitted, and a number of new ones, which have stood the test of time and trial, added. Among other improvements and additions, the following deserve mention:

In Part II. are inserted Zinsser's anaërobic method for plate-cultures and three new methods for the cultivation and differentiation of the typhoid bacillus, the ox-bile method, the medium of Endo, and the malachite green medium. The paragraphs on the micro-organism of actinomycosis have been entirely rewritten to accord with recent investigations on this subject.

In Part III. the following additions will be found: Weigert's iron hematoxylin stain for nuclei; improvements in the methods for staining fibroglia, myoglia, and neuroglia fibrils; Wright's method for the differential staining of blood-platelets and the giant cells of the bone-marrow; Best's improved stain for glycogen; von Kossa's silver method for demonstrating lime-salts; staining methods for the treponema pallida; and Sir A. E. Wright's method of preparing bacterial vaccines.

BOSTON, July, 1908.

9

PREFACE TO THE FIRST EDITION.

THIS book is designed especially for practical use in pathological laboratories, both as a guide to beginners and as a source of reference for the advanced. We believe that the book will also meet the wants of practitioners who have more or less opportunity to do general pathological work.

Every autopsy presents for solution a problem which may be simple or complex. The known quantities are certain clinical symptoms and physical signs; the unknown quantities are not only the gross and microscopic lesions that may or may not have given rise to the symptoms and signs, but also the etiology of the lesions and the order of their sequence. The solution of the problem often requires the highest skill in post-mortem, bacteriological, and histological technique, but in its solution lies the fascination of pathological work.

It has seemed advisable to us to present, so far as possible, a consecutive statement of the methods employed in solving the various problems that arise, so as to avoid the repetitions that necessarily occur when the three usual divisions of the subject are separately considered by different writers. It is hoped that this method of presenting the subject will bring the student to the realization that the mechanical performance of a post-mortem examination and the inspection of the gross lesions constitute usually only the beginning of the solution of the problem, which should be investigated

bacteriologically, histologically, and chemically as far as our present knowledge will permit.

We should particularly advise the routine bacteriological and histological examination of the more important organs in all suitable cases. Naturally, the autopsies in which the lesions are due to a single etiological factor are the most valuable and instructive for a clear understanding of the pathological processes present.

Besides the methods of post-mortem examinations and of bacteriological and histological investigations connected with autopsies, we have added the special methods employed in clinical bacteriology and pathology.

In the parts devoted to Bacteriology and to Pathological Histology we have not endeavored to make an exhaustive collection of methods and formulæ, but rather to select those which have been found of the greatest service in practical work.