vi PREFACE 



progress. Having the courage of his convictions along these 

 lines, the writer has spent much time which he might other- 

 wise have spent on original research in the compilation and popu- 

 larization of the subject matter of this book. 



It is the aim of this volume to present the important facts of 

 parasitology, as related to human disease, in such a manner as 

 to make it readable and useful not primarily to the parasi- 

 tologist, but to the public health and immigration service officers ; 

 to the physicians who are concerned with something more than 

 their local practice; to teachers of hygiene, domestic science or 

 other subjects in which health and preventive medicine are im- 

 portant; to college and high school students; to the traveler; 

 and to the farmer or merchant who is interested in the progress 

 of science and civilization. It is the hope of the author that 

 this book may not only be a means of making available for the 

 laity facts which may and probably will be of direct importance 

 to them at one time or another, but that it may also be instru- 

 mental in arousing the interest of more students in this branch 

 of science, to the ultimate end of enlisting a larger number in 

 the ranks of its workers. 



No attempt has been made in the following pages to give 

 detailed descriptions of parasites, or to go further into their 

 classification than seemed necessary to give a correct conception 

 of them. Likewise discussions of correct scientific names and 

 synonymy have been entirely omitted, since, important and 

 interesting as they may be to a parasitologist, they are of no 

 interest to the lay reader. An attempt has been made to use 

 scientific names which are most generally accepted as correct, 

 except that in cases of disagreement between American and 

 European usage, the American name has been used. In cases 

 where some other name than that adopted in this book has been 

 or is still in common use, it is given in parenthesis to afford a 

 clue to the literature associated with it. 



The endeavor to avoid repetition in the discussion of certain 

 parasites in one chapter, and of their transmitting agents in 

 another, has often presented difficulties, since some facts might 

 equally well be included in either place. As far as possible 

 these facts have been given in the place where the author has 

 felt that they would most often be sought, but mistakes have 

 undoubtedly been made, and furthermore what one reader would 



