viii PREFACE 



their parasitism, in the minds of physicians in gen- 

 eral was hazy indeed. Intestinal protozoa were 

 parasites to be gotten in the tropics, the produc- 

 ers of amoebic and other tropical dysenteries. An 

 amoeba was an amoeba and a flagellate was a ^'cer- 

 comonas" ; most of the species now of familiar names 

 were unknown to them, some were unrecognized by 

 anyone. 



Since that time, perhaps due largely to the in- 

 terest incident to the world war and the care of large 

 bodies of troops and other people, but primarily due 

 to the persistent efforts of a few whose interest and 

 knowledge in this field came into play under the con- 

 ditions of war organization, the whole subject has 

 come into general prominence. Much valuable in- 

 formation has been added by careful scientific in- 

 vestigators, but a great deal of undigested writing, 

 especially by physicians who have not had particular 

 regard for scientific methods, has been done. Con- 

 sequently there exists considerable chaff with the 

 grain, and the medical profession has been fairly 

 confused by it. 



During recent times there have been published sev- 

 eral excellent books which cover the field in various 

 fashions, such as Wenyon's Protozoology, Calkin's 

 Biology of the Protozoa, Craig's Parasitic Protozoa 

 of Man, Human Protozoology by Hegner and Talia- 

 ferro, Chandler's Animal Parasites and Human Dis- 

 ease, The Intestinal Protozoa of Man, by Dobell and 

 O'Connor, and others, to which works the author re- 

 fers those who desire biological information beyond 



