Introduction

This book is an attempt in response to the editor of this science series to set forth a popular scientific statement. Theoretical and practical textbooks of Bacteriaology, plantively exist both in England and America. It should be understood that the outline drawings are only of a diagrammatic nature. I am much indebted to Professor Crookshank, who in reading the manuscript has helped me by many valuable criticisms. My thanks are also due to Sir C.T.D. Acland for many kind suggestions,. E.J. Spitta, M.R.C.S., who has been good enough to take a number of excellent photo micrographs for him. Some other illustrations