PREFACE 



Numerous textbooks of varying degrees of excellence for the study 

 of Protozoa are now on the market and should be consulted for a 

 general treatment of these unicellular forms. This volume will not fill 

 such a need, but has been prepared as a result of a discussion by a 

 group of specialists assembled during the summer of 1937 at the 

 Marine Biological Laboratory at Woods Hole, Massachusetts, for the 

 purpose of ascertaining the best means to stimulate further research 

 on these unicellular animals. 



As a result of these discussions it was decided that one good way to 

 attain our end would be to have a group of specialists in the field of 

 proto2o5logy prepare a work on research in this field, each specialist 

 to provide a chapter on the subject in which he is best known, and 

 about which he can speak with authority. 



Our first real difficulty was to select a limited number of topics from 

 a vast number of possibilities, and then to choose the biologists who, in 

 our opinion, were the best men to write these chapters. As can be 

 readily imagined, this opened up a long list of difficulties and led to 

 many vexatious troubles, but the present work, finally, is the outcome. 



To our very great regret, one of the men chosen — Professor Noland, 

 of the University of Wisconsin — who was most enthusiastic over the 

 project, has been forced by reason of continued illness, to drop out. 

 The loss of others, on the plea of pressure of work, and so forth, has 

 also depleted our ranks. But the remainder have completed their labors, 

 have come through, and the results here speak for their continued in- 

 terest and assiduity. 



While the arrangement of our material does not make a great 

 deal of difference, some order nevertheless is advantageous, and we 

 have therefore arranged the chapters, according to the general character 

 of their materials, into groups having a more or less common subject 

 matter. 



Gary N. Calkins 

 Francis M. Summers 

 New York City 

 January 2, 1941 



