PREFACE 



The first purpose of this book is to supplement a lecture course on microbial 

 genetics with original readings in a form most readily available to the student. 

 At most universities, the papers included in this collection will be represented 

 by single copies of the original journals. Thus, it is usually difficult for any 

 number of students to read the papers at all, and impossible for anyone (includ- 

 ing the instructor) to read and perhaps annotate them at leisure. This volume 

 is not intended to include all the reading on this subject which should be 

 required for a course. I hope, however, that it will make available most of 

 the papers requiring the most general or the most intensive study. 



The scope of the collection must obviously have some limits in size and 

 cost. These have led to the restriction to bacteria and bacterial viruses, although 

 consideration of fungi, protozoa, algae, and viruses is essential to a well-rounded 

 course, even to one organized, as at Wisconsin, primarily for students majoring 

 in bacteriology. Within this field, there are a great many important papers 

 which have necessarily been omitted. No apologies need be offered for a selection 

 which must be largely arbitrary. The papers selected were those which seemed 

 to illustrate best certain concepts and methodologies for the benefit of a course 

 in microbial genetics. In some choices, weight had to be given to other 

 circumstances such as the length and availability of alternative papers. It must 

 be emphasized that these selections do not reflect historical priority or scientific 

 worth as such. A bibliographic list is included to help remedy the unavoidable 

 deficiencies of the collection. 



This book could not have been produced without the magnanimous coopera- 

 tion of the publishers and copyright holders of the original papers, to whom 

 specific acknowledgment is made elsewhere. Special thanks are due to the 

 authors who have been very helpful, especially in providing scarce reprints for 

 use as copy. I must also record an obligation to my colleagues who did their 

 best to advise me on the proper scope and contents of this collection. 



j. L. 

 Madison, April i, 1951 



