Vlll. PREFACE 



The third part is devoted to bacterial diseases, to the 

 effects of certain animal and vegetable poisons, and to 

 certain diseases the causation of which is unknown or 

 but imperfectly understood. 



The advantages of this arrangement are considerable, 

 as the general outline of the prophylactic measures 

 required differs for the diseases described in each part. 



Thus the measures described in the first part are 

 mostly directed against arthropoda, insects or arachnida, 

 which act as intermediate or alternative hosts for the 

 malarial and other protozoal parasites. The measures 

 described in the third part, including as they do those 

 for dealing with cholera, enteric fever and plague, 

 involve the consideration of the protection of water 

 supplies, the disposal of sewage, disinfection and other 

 sanitary problems ; while the measures dealt with in the 

 second part include some directed against insects, as in 

 the case of filariasis, and others, e.g., those for the preven- 

 tion of endemic haematuria and ankylostomiasis, dealing 

 with the water supplies and sewage disposal ; in both 

 cases, however, involving somewhat different problems 

 from those discussed in the other two parts of this work. 



Suitable technical methods of a simple character, as 

 well as data and measurements in common use, are given 

 in an appendix to each part. 



We are much indebted to numerous friends and past 

 students of the London School of Tropical Medicine 

 for valuable hints and aid in revision of proofs. Major 

 J. B. Smith, Major ]. H. McDonald, of the I. M.S., 

 Dr. Venis, and Dr. H. B. Newham must be specially 

 mentioned. The charts used for the illustrations are in 

 most instances those of patients at the Albert Dock 

 Hospital of the Seamen's Hospital Society, to which is 

 attached the London School of Tropical Medicine. 



