PREFACE TO THE FOURTH EDITIOX. IX 



have already appeared in my Reports to the Board of 

 Agricvdture and in other pnblications. 



One hundred and thirty-three woodcuts and photographs 

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

 which J 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 reprodnce some of the photographs 

 in his excellent Atla>. 



I am particularly indebted to Professor Hamilton for 

 the use of cliches of figures in his classical treatise on 

 Pathology, and to the ZSew Sydenham 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. 



Saixt Hill, East Geixstead. Sussex, 

 Avgiiit 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. 



September 18«, Is^G. 



