EDITORS' PREFACE 



At the time of his death on October 17, 1956, Mark Adams 

 had written all but four chapters of the present book. Messrs. 

 Anderson, Gots, Jacob, and Wollman contributed the remainder, 

 completing the text according to Adams' plan. 



The original chapters were written over a period of several 

 years. They had to be revised, completed, and brought up to 

 date, with a minimum of editorial changes. The necessary work 

 was done by S. Benzer, G. Bertani, M. Delbriick, A. Garen, W. 

 Harm, R. M. Herriott, A. D. Hershey, F. Lanni, R. G. E. Mur- 

 ray, F. W. Stahl, G. S. Stent, G. Streisinger, J. D. Watson, and 

 J. J. Weigle. Hershey is responsible for the form in which these 

 chapters now appear. 



E. Kellenberger and his colleagues furnished many electron 

 micrographs, and assisted in the selection and presentation of 

 those appearing in this book. Unless otherwise stated, specimens 

 were prepared by Kellenberger's agar filtration method (see 

 Chapter XI), shadowed with uranium oxide, and translated to 

 film in the RCA-EMU 2 microscope. 



Appreciation is due the Year Book Publishers, Inc., Chicago, 

 Illinois, for permission to reprint, as an appendix to this volume, 

 "Methods of Study of Bacterial Viruses," from Vol. 2 of Methods 

 of Medical Research. The appendix was edited by Rollin D. 

 Hotchkiss and Nancy Collins Bruce. 



Carnegie Institution of Washington A. D. Hershey 



Cold Spring Harbor, New York for the editors 



June, 7958 



