Preface 



THE present work is similar in its primary aim to that of its 

 predecessor, Handbook of Protozoology (1931), in presenting 

 "introductory information on the common and representative 

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

 to advanced undergraduate and graduate students in zoology in 

 colleges and universities. With the expansion of courses in proto- 

 zoology at the University of Illinois and elsewhere, it seemed ad- 

 visable to incorporate more material for lecture and discussion, 

 in addition to the enlargement of the taxonomic section. The 

 change of the text-contents has, therefore, been so extensive that 

 a new title. Protozoology , is now given. 



Chapters 1 to 6 deal with introduction, ecology, morphology, 

 physiology, reproduction, and variation and heredity, of Proto- 

 zoa, Each subject-matter has been considered in the light of more 

 recent investigations as fully as the space permitted. Selection of 

 material from so great a number of references has been a very 

 difficult task. If any important papers have been omitted, it was 

 entirely through over-sight on the part of the author. 



The taxonomic portion (Chapters 7 to 43) has also been com- 

 pletely rewritten and enlarged. Numerous genera and species, 

 both old and new, have been added; synonymy of genera and 

 species has as far as possible been brought down to date; new 

 taxonomic arrangement of major and minor subdivisions in each 

 class has resulted in numerous changes. The class Ciliata has 

 completely been reclassified, following Kahl's admirable work on 

 free-living ciliates (1930-1935); however, unlike the latter, all 

 parasitic ciliates have also been considered in the present work. 



The author continues to believe that good illustrations are in- 

 dispensable in this kind of work, since they are far more easily 

 comprehended than lengthy descriptions. Therefore, many old 

 illustrations have been replaced by more suitable ones and nu- 

 merous new illustrations have further been added. All illustrations 

 were especially prepared for this work and in the case of those 

 which have been redrawn from illustrations found in published 

 papers, the indebtedness of the author is indicated by mention- 

 ing the names of the investigators from whose works the illustra- 



