Preface to the second edition 



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 protozoology at the 

 University of Illinois and elsewhere, it seemed advisable to incorpor- 

 ate more material for lecture and discussion, in addition to the en- 

 largement of the taxonomic section. The change of the text-contents 

 has, therefore, been so extensive that a new title, Protozoologij , 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 diffi- 

 cult task. If any important papers have been omitted, it was en- 

 tirely 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 ar- 

 rangement of major and minor subdivisions in each class has resulted 

 in numerous changes. The class Ciliata has completely been reclassi- 

 fied, 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 illustrations have been replaced by more suitable ones and numerous 

 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 mentioning the names of 

 the investigators from whose works the illustrations were taken. In 

 order to increase the reference value, all figures are accompanied by 

 scales of magnification which are uniformly somewhat greater than 

 those of Handbook of Protozoology, since the microscope now used in 

 the class-room has been improved upon in recent years. 



