PREFACE TO THE FOURTH EDITION. IX 



have already appeared in my Reports to the Board of 

 Agriculture and in other publications. 



One hundred and thirty-three woodcuts and photographs 

 have been added in the text, and I have reverted to the plan 

 which I adopted in the second edition, of having many of 

 them printed in colours. 



I take this opportunity of thanking Professor Frankel for 

 kindly permitting me to reproduce some of the photographs 

 in his excellent Atlas. 



1 am particularly indebted to Professor Hamilton for 

 the use of c//W//.v of figures in his classical treatise on 

 Pathology, and to the New Syclenham Society for several 

 from the English translation of Professor Fliigge's well- 

 known work on micro-organisms. 



To my Demonstrator, Dr. George Xewman, D.P.H., I am 

 indebted for much assistance in correcting the proof-sheets, 

 and for the preparation of an index. 



EDGAR M. CROOKSHAXK. 



SAINT HILL, EAST (THIN-STEAD. Srssj-jx. 

 August 1st, 1896. 



P.S. Since this work was finally passed for press the con- 

 clusions of the Royal Vaccination Commissioners have been 

 published. I have at the last moment added extracts in the 

 form of a supplementary Appendix. E. M. C. 



