FOREWORD 



These reports* from various members of our staff and the effort as a whole 

 are of the nature of a research exploration to get a general survey of the 

 problem and to choose the most promising aspects for future exploration. 

 These reports are by no means considered to be anything but a step to 

 further research and are given here with the hope that they will show vari- 

 ous aspects of attack and that they will enlarge the perspective of those 

 who wish to join in the study. 



To put this volume through the press with a number of authors on various 

 papers of scientific endeavor, with many different kinds of illustrations has 

 required much scrutiny and discussion. Its completion is due to the con- 

 sistent efforts of our librarian, Mrs. Anne Himmelberger Longenbach, and 

 her two efficient assistants, Misses Mary Pearce and Alary ^'irginia Gard- 

 ner. When it came to precision and constructive criticism, their "spear 

 knew no l^rother". I take this opportimity of publich' tendering my 

 grateful acknowledgment. 



Ellice McDonald. 



Biochemical Research Foundation, 

 Newark, Delaware. 



* Since writing this book, we have advanced considerably in our research to ex- 

 plain the mechanism of radiation on mammalian cells. It is my regret that these 

 findings have come too late for incorporation in this book and must wait for a later 

 publication. 



Ellice McDonald 



