Most of the references in this volume concern papers published between 1960 and 1962. The index includes volumes 16 and 17, the first two of the fourth series. It also contains additional or revised entries to former volumes. I again wish to acknowledge with gratitude the help and advice I have had from Dr. John T. Plati, Dr. Bernhard Prijs, and Mr. Peter Schneider. I also want to thank Dr. William R. Sullivan, Director of Research Services, for his kind cooperation in matters concerning Hoffmann-La Roche Inc., Nutley, N. J., as headquarters of this enterprise, and Mrs. Carole Majdanski for skilled secretarial help.