A Manual Of Bacteriology. PREFACE TO THE FIFTH EDITION. IN the preface to the second edition of this manual the author states that the purpose of this book is to give in the smallest possible space the facts which a physician must know, with some of those which it is desirable that he should know, and a little of that which he may learn if his needs or inclinations lead him to go further. While in the present edition this purpose has been kept in mind by the reviser, nevertheless it has been necessary to make many alterations in order to place the work abreast of the progress which has been made since the publication of the last edition. Some things which have become obsolete have been omitted, much that is new has been added, and the scope has been somewhat widened. Since the book is designed primarily for medical students, the method of expression, as in former editions, is often more definite than is perhaps justifiable, and it must be understood that this form is adopred merely in order to make a clear presentation of the subject, not that the matter is in every such case finally settled, nor that the views as stated are necisarily shared by tbe author or the reviser, but that they are held by those whose opinions are worthy of consideration, and are the interpretation of the results of painstaking investigation, but which, nevertheless, may be in time modified or abandoned as a result of further research. Those who are familiar with the former editions of the book will find that the arrangement of chapters is the same as heretofore.