INTRODUCTION 3 



germane to my present purpose, which is to collect and coordinate all 

 our present zoological knowledge of the amoebae which live in man. 

 My original intention was to confine myself to the intestinal amoebae ; 

 but this soon became almost impossible, as the others had so frequently 

 to be discussed or compared. I decided, therefore, to attempt to deal 

 with all the amoeboid organisms which have been described from 

 human beings. My work is obviously incomplete and faulty in many 

 ways, but even these deficiencies may have their uses : for the mere 

 exhibition of a glaring defect, or the clear definition of a difficulty, 

 frequently hastens the advance of science by indicating a pitfall or 

 a wrong road of inquiry. 



Although I have always formed my opinions independently, and 

 attach — as every honest worker must — particular importance to my own 

 personal observations, I have undoubtedly been influenced, in the 

 present work, by the advice and assistance which I have received from 

 my fellow-workers. Such help is impossible to assess, or even to define. 

 My obligations in this respect are none the less immense, and I can at 

 least attempt to acknowledge them. In the first place, my indebtedness 

 to Dr. C. M. Wenyon — now Colonel, A. M.S. — is gratefully recorded. 

 When I began to study the amoebae of man in earnest, his help — always 

 most generously given — was invaluable. I learnt more in conversation 

 with him than I had ever previously learnt from books. My ignorance 

 of medicine has to some extent been compensated by working in 

 collaboration with other medical friends, who have always given me 

 help and instruction in the kindest possible manner. In this connexion 

 I am glad of an opportunity to acknowledge my obligations to Dr. H. H. 

 Dale, F.R.S., with whom I had the good fortune to work in the early 

 days ; to Dr. A. C. Stevenson, of the Wellcome Bureau, who has shared 

 much arduous work with me throughout, and with whom I have dis- 

 cussed — with much profit to myself — most of the questions here 

 considered ; and to Dr. G. C. Low, whose extensive clinical experience 

 has always been freely placed at my disposal. For much good advice 

 and frequent assistance in bacteriological matters I am further indebted 

 to Capt. S. R. Douglas, I. M.S. (ret.) and to the late Dr. H. S. Gettings. 



The friendis, pupils, and fellow-workers who have helped by giving 

 me material, by supplying me with information, or by directing my 

 attention to various points of interest, are innumerable. But in this 

 connexion I would again thank the following for their assistance on 

 divers occasions : Captain F. W. O'Connor, R.A.M.C, Dr. P. P. 

 Laidlaw of Guy's Hospital, Dr. E. H. Kettle of St. Mary's Hospital, 

 Dr. G. T. Western of the London Hospital ; and Messrs. H. A. Baylis, 

 the late W. O. Redman King, A. Malins Smith, J. R. Matthews, 

 Geoffrey Paget, R. E. Savage, A. G. Thacker, and Hugh Watson. Miss 

 M. W. Jepps, who for a time acted as my assistant, has also given me 

 much help. I am further indebted to Captain F. L. Armitage, N.Z.M.C., 

 for specimens from a case of amoebic abscess of the brain ; to Dr. 

 J. W. Scott Macfie for material from a case of " urinary amoebiasis " ; 

 and to Mr. T. Goodey for some preparations of Entamoeba gingivalis. 

 Several patients with interesting amoebic infections have also given me 

 the greatest assistance by submitting themselves to repeated and irksome 

 examination. Though nameless here, they are neither forgotten nor 

 unthanked. 



Much of the work whose results are here recorded has been carried 



