10 PREFACE 



The pathogenic protozoa constitute a group which is particu- 

 larly difficult to treat adequately, largely due to the rapid growth 

 of the subject. Relatively few of the forms, moreover, are of 

 immediate interest to the North American student. 



I wish gratefully to acknowledge the assistance of my wife in 

 the preparation of illustrations and revision of manuscript, that 

 of Mr. Chas. Murray in proof reading, and that of Dean Chas. C. 

 Stange and Dr. Murphy, of the Division of Veterinary Medicine, 

 for critical reading of the manuscript. 



R. E. BUCHANAN. 



IOWA STATE COLLEGE, AMES, IOWA. 

 July, 19 11-. 



