PREFACE.

THE following book, with few additions, is a reprint of a series of articles that have appeared in the Practitioner (1884). Not pretending to be in any sense an exhaustive treatise it will, I hope, nevertheless serve to illustrate most of the important points bearing on investigations into the life history of micro-organisms connected with infectious diseases.

I must not omit to mention that most of the investigations recorded here were carried out for the Medical Department of the Local Government Board during the past ten years.

E. KLEIN.