PREFACE 



The editors of this book have attempted to bring together 

 information of value to students and investigators in the field of 

 Protozoology that is at present either widely scattered in the liter- 

 ature or has never before been published. In the first half of the 

 nineteenth century it was possible for a scholar to treat in one 

 volume a large part of the existing knowledge of protozoology: 

 but specialization has entered this field as well as other fields of 

 science and now each student has a comprehensive knowledge of 

 only one or a few groups of protozoa or of only one or several 

 phases of their host-parasite relations. As a result of this tendency 

 an investigator in one field has difficulty in keeping up with the 

 problems and methods of research in other fields. Furthermore 

 those who wish to take up protozoology as a career are unable 

 to secure from any easily accessible sources an adequate idea of 

 problems available for study and of methods that may be em- 

 ployed in their study. 



This volume has been organized with the purpose of aiding 

 both the seasoned investigator and the beginning student. The 

 editors intended at first to prepare the entire manuscript themselves 

 but it soon became evident that the work would be much more 

 valuable if specialists in each field were to contribute chapters 

 on problems and methods of research in the various phases of the 

 subject about which they were most familiar. The response to 

 our invitation to contribute was very gratifying and we believe 

 that we are able to present to protozoologists a book that will be 

 of great value not only to their own investigations but to the 

 general subject to which we are devoting our time and energy. 



The editors wish to thank the contributors to this volume for 

 their cooperation and also the publishers for their willingness to 

 undertake the responsibility for a book of this type which can 

 hardly be a financial success. 



Robert Hegner 

 Justin Andrews 



