THE AMOEBAE LIVING IN MAN. 



I. 



INTRODUCTION. 



I FIRST became interested in the amoebae which live in man some 

 twelve years ago. I was then investigating the amoebae of frogs, 

 and the observations which I made led me to study much of the 

 published work dealing with the related rhizopods occurring in man and 

 other animals. At that date Schaudinn's views were generally accepted ; 

 and so great was his prestige, that to question any of his pronounce- 

 ments in protozoology was almost to stamp oneself — in the estimation of 

 most zoologists and medical men — as an inexperienced or incompetent 

 worker. Nevertheless, my own observations soon constrained me to 

 believe that Schaudinn's conclusions regarding the intestinal amoebae 

 of man were mostly incorrect — as time has since shown convincingly : 

 but although 1 have always thought that my conclusions concerning 

 the development of the amoebae of frogs would ultimately prove to be 

 equally applicable to the species living in man, I was long unable to 

 verify this owing to my inability to obtain adequate material for a study 

 of the latter organisms. 



In the meantime, the wrong road of inquiry opened up by Schaudinn 

 was eagerly explored by many other workers : with the result that our 

 " knowledge " of the intestinal amoebae was soon a muddle of facts, 

 misinterpretations, malobservations, and fanciful speculations, from 

 which — only a few years ago — it seemed almost impossible to extricate 

 the truth. 



For some years I followed, with the greatest interest, all the work 

 published on this subject — noting the various " new species " from time 

 to time discovered, reading the writings of the older observers as oppor- 

 tunity occurred, and forming my own opinions of them to the best of 

 my ability. But I very soon realized that my opinions were almost 

 worthless without a very extensive first-hand acquaintance with all the 

 organisms under discussion : and consequently, whilst I criticized and 

 controverted many of the accepted views in conversation, in correspon- 

 dence, and in my lectures at the Imperial College, I did not permit 

 myself to express any opinions in print. Of this I am now glad, because 

 experience has taught me that it is impossible to draw correct con- 

 clusions from merely studying what has been written on this subject. 

 I thought too, and still think, that it is a mistake to confine oneself, in 

 dealing with such a subject, to the parasitic forms ; and my own work 

 has, accordingly, been carried out as a part of a more comprehensive 

 study of the amoebae generally — both parasitic and free-living. 



