INTRODUCTION 



The problem of the status of the protozoa of the 

 ahmentary tract in relation to health and disease is 

 of great medical and economic importance. 



When we consider the great and world-wide prev- 

 alence of this class of parasites, the great number of 

 people who are not in good health who carry one or 

 more of species of these organisms, the great number 

 of people who are being treated by physicians over 

 extended periods of time with the finding of intes- 

 tinal protozoa as the basis of treatment, the subject 

 becomes of large proportions and of great consequence 

 to the public of the world. This is a responsibility 

 which the author w^ould bring to the medical profes- 

 sion. 



The second responsibility which belongs to them 

 in the matter is this. The search for and identifi- 

 cation of alimentary tract protozoa in the practice of 

 medicine, as done in this country outside of recognized 

 medical centers, is largely in the hands of unquali- 

 fied people. 



To many people who assume the responsibility for 

 identifying protozoa in the feces and of playing some 

 part in^ evaluating their relations to disease, that 

 all-important body, the protozoan cyst, is an un- 



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