X PREFACE 



black and white and coloured, the writer is much indebted to Mr. B. 

 Jobling, now on the staff of the Wellcome Bureau of Scientific Research. 

 His knowledge of biology combined with his artistic skill has enabled 

 accurate copies and many original drawings from preparations to be 

 produced. The writer's thanks are also due to his sister, Miss M. G. 

 Wenyon, Assistant Secretary to the Royal Society of Tropical Medicine 

 and Hygiene, who has read carefully the final proofs, and has been a 

 means of detecting errors which otherwise would have marred the pages. 



The writer is indebted to Professor Nuttall, F.R.S., Quick Professor 

 of Biology and Director of the Molteno Institute of Cambridge ; Dr. A. G. 

 Bagshawe, C.M.G., Director of the Bureau of Hygiene and Tropical 

 Diseases ; Professor Warrington Yorke of the Liverpool School of Tropical 

 Medicine; Professor A. E. Boycott, F.R.S., of University College, London; 

 Lieut.-Col. W. P. MacArthur, D.S.O., O.B.E., of the Royal Army Medical 

 College; Dr. Keilin of the Molteno Institute, Cambridge; and the Councils 

 of the Royal Society of Tropical Medicine and Hygiene and the Royal 

 Institution for the loan of blocks. He is also indebted to Mr. Clifford 

 Dobell, F.R.S., for the use of his original diagrams of Aggregata eberthi 

 and his drawing of the cyst of Balantidium coli, and for permission to 

 reproduce figures from his publications. 



Much assistance has been derived from many of the books on Proto- 

 zoology or one or other of its branches, particularly Doflein's Lehrhuch 

 der Protistenkunde, Laveran and Mesnil's Trypanosomes et Trypanoso- 

 miases, Laveran's Leishmanioses, Minchin's An Introduction to the Study 

 of the Protozoa, Dobell's The Amoehce Living in Man, Dobell and O'Connor's 

 The Intestinal Protozoa of Man, and many others; but of all the publica- 

 tions, apart from original articles, the careful reviews by Professor Mesnil 

 which have appeared regularly in the Bulletin de VInstitut Pasteur since 

 1902, and those by various writers in the Tropical Diseases Bulletin, 

 have been most helpful. Any worker who wishes to keep abreast of 

 the times cannot do better than to read one or both of these excellent 

 bulletins with regularity. 



Finally, the writer wishes to express his thanks to Mr. N. B. Kinnear 

 of the British Museum, Natural History, for the trouble he has taken 

 in checking the host list of birds, and to all the many others who have 

 been ever ready to give him valuable assistance. 



C. M. W. 

 London, 

 June, 1926. 



