American Scientist

We Can Sleep Later: Alfred D. Hershey and the Origins of Molecular Biology. Franklin W. Stahl (ed.). xii + 359 pp. Cold Spring Harbor Laboratory Press, 2000. $39.

The focus in molecular biology in the 1950s was on whether DNA, protein or some combination of the two was the heritable material passed between cells. The work of Alfred D. Hershey, Max Delbr?ck and Salvador E. Luria answered this question and led to their sharing the Nobel Prize for Physiology or Medicine in 1969. In We Can Sleep Later, well-known molecular biologists share personal and professional memories of Hershey, giving readers an inside view of the early days of their field. A memorial to Hershey, who died in 1997, the volume includes selections from Hershey's own writings as well as essays and reminiscences contributed by his colleagues. We see Hershey first through the eyes of others. Eleven essays, occupying the first 80 pages of the book, combine appreciation of Hershey's work with views of the man himself. These are followed by a section containing shorter reminiscences.

Both the essays and the reminiscences offer much material that is intriguing. Unfortunately, many of the stories about Hershey are somewhat similar to one another, and it often happens that one story is retold by several contributors. Hershey was respected as a consummate editor and was noted for crossing out whole pages or sections of drafts; it's too bad that the editor of this collection was not as fervent. One version of a tale about Hershey's editorial pen has him deleting 4 pages of a manuscript by Mark Ptashne and another says it was 11 pages; eventually, we learn from Ptashne himself that it was the first 3 pages that were excised.

Perhaps Hershey's personality helps explain why some stories about him were widely circulated: He was a man of few words, but what he did say had an impact and was likely to be talked about. Nearly every contributor mentions that Hershey was an intensely focused, personal man, given to straight yes or no answers?if he answered at all. In a tribute to Hershey that originally appeared in the New York Times, James D. Watson notes that Hershey's hour-long concluding remarks at the annual phage meeting at Cold Spring Harbor "struck those of us aware of his acute taciturnity as containing more words than he might have spoken to outsiders over the course of the past year."

Despite some redundancy, these pieces give us a clear picture of the man whose experiments played such a critical role in determining that DNA rather than protein is the source of inheritance. It was Hershey's personality that drove the critical experiments, which were so meticulous that perhaps no one else could or would have performed them.

In what is by far the longest section of the book, some of Hershey's most influential scientific papers are reprinted. Several pieces stand out as gems that show how to present excellent work concisely and directly. These make the section worth reading even for those not particularly interested in the subject matter.

Much of Hershey's work dealt with the nuances of bacteriophage genetics. Although the technical details of phage genetics are themselves confusing at times, the experimental details, results and interpretations put forth by Hershey are elegant in their simplicity. Among his major achievements was the determination that phage genes were linked along chromosomes in much the same way as genes in higher organisms. In his famous Waring blender experiment, he and his assistant Martha Chase showed that bacteriophage T2 DNA was necessary for inheritance rather than its associated protein. Through his phage explorations he developed key methods that remain heavily used today. For example, his searches for the number and size of phage T2 chromosomes led him to develop chromatographic and centrifugal methods that are still commonplace. Another major contribution was Hershey's identification of "sticky ends" in the DNA molecule of bacteriophage l: These complementary DNA overhangs are the basis for most types of recombinant biology. Throughout this section, Hershey's matter-of-fact presentation of the data is refreshing.

This collection opens a unique window into the early days of molecular biology and the life of an extremely private scientist to whom personal satisfaction with an experiment well done was more important than acclaim. The reader is left with a feeling of regret that Hershey and his brand of methodical, concise science are no longer with us.