This completely revised, updated, and expanded edition has been neces­ sitated by the many important newer discoveries that have been made since the publication of the first edition. That volume contained almost 2000 references from the 1600s to 1953. Since then and after an extensive search, I have accumulated some 3800 additional titles from the world's literature on Paramecium. After certain titles that largely represented abstracts and preliminary reports that were followed by full research papers were eliminated, approximately 4400 full titles from the 1600s to the present were selected for inclusion in this edition. Most of the titles in the Bibliography are the more recent ones beginning with 1953. I consider the Bibliography an important part of the book: A good title of a paper in a journal is a minature abstract of its contents. Thus, the reader who may be interested in obtaining additional information not found in the book may refer directly to the original source. A cursory examination of the Bibliography will reveal that parame­ cium research has extended into all branches of biology, including bio­ chemistry and biophysics. Like other areas of science, paramecium research has become highly specialized and fragmented. I have attempted to organize and present the basic information in one book. Because of space limitations, some items may have been dealt with briefly. It is in such instances that the Bibliography will be found to be invaluable.