Preface to the third edition 



IN REVISING Protozoology for the second time, the author has 

 maintained the original aim of the work for setting forth "in- 

 troductory information on the common and representative genera 

 of all groups of both free-living and parasitic Protozoa," and en- 

 deavored to limit its expansion to minimum. Errors, typograph- 

 ical and otherwise, which had appeared in the last edition have been 

 corrected. In this he is much indebted to his former students, both 

 graduates and undergraduates, who untiringly detected them and 

 suggested improvement of many passages for clearer presentation. 

 The criticisms offered by the reviewers of the second edition have 

 also been considered. 



Published papers that had been overlooked before and those that 

 have appeared in the last six years have been consulted and referred 

 to in the present edition. Chapters 4 to 6 were largely rewritten and 

 enlarged in the light of recent works. Alterations and additions have 

 been made in all other chapters. Two new chapters have been added; 

 they are chapter 7 (Major groups and phylogeny of Protozoa) and 

 chapter 45 (Collection, cultivation, and observation of Protozoa). 



Since there is now a greater demand of the information on Proto- 

 zoa that parasitize man than in the past, they have been more 

 thoroughly treated in the present edition. 



The author continues to believe in the importance of adequate 

 illustrations in this sort of work. Sixty-nine new figures have been 

 added; of these forty-seven have been newly prepared or rearranged 

 from former figures, while twenty-two have been taken from his 

 Manual of human Protozoa (1944). 



The author once more expresses his indebtedness to numerous 

 authors of published papers for the materials which have been in- 

 corporated in the work. He is under special obligation to Doctor 

 Harold Kirby, University of California; Doctor Reginald D. Man- 

 well, Syracuse University; Doctor Tracy M. Sonneborn, Indiana 

 University; Doctor David H. Wenrich, University of Pennsylvania; 

 and Doctor Lorande L. Woodruff, Yale University, for their kind 

 advices, sincere criticisms and suggestions. He further wishes to 

 thank Mr. Charles C Thomas for the interest and care with which 

 the present edition has been put in print. 



Richard R. Kudo 

 Urbana, Illinois 

 October, 1945 



