THE CSHL ARCHIVES BLOG: DNA Letters, 1951-1953

In honor of the 60th anniversary of the discovery of the structure of DNA, we are proud to present a series of letters related to the famous discovery, all of which are housed at the CSHL Archives. Enjoy.

These letters, collected from the James D. Watson Collection and the Francis Crick series of the Sydney Brenner Collection, tell several stories regarding the lead up to the discovery of the double helix structure of DNA. The letters illustrate the many difficulties that almost prevented Watson and Crick from ever meeting, let alone collaborating. Even after the two paired up, trouble seemed to follow. The letters between Crick and Maurice Wilkins illustrate the many conflicts and personalities involved in the DNA discovery. After the discovery, letters between Milislav Demerec, Max Delbrück, and Watson discuss the first presentation of the double helix to the world at the 1953 CSH Symposium.

Letter from Max Delbrück to the Chicago Selective Service Board
20 March 1951
Courtesy of the James D. Watson Collection

At age 23, it was very possible that Watson could have been drafted into the military to serve in Korea. In this letter Max Delbrück explains, “That there is no question in my mind that it is of the national interest to permit Dr. Watson to continue his studies and research.” Watson would remain deferred, and was allowed to continue his scientific studies, which eventually led him to Cambridge and Francis Crick.

Letter from Herman M. Kalckar to C.J. Lapp
5 October 1951
Courtesy of the James D. Watson Collection

After receiving his PhD from Indiana University, Watson received a National Research Council Fellowship to study nucleic acid chemistry under Herman M. Kalckar in Copenhagen. Watson did not enjoy his biochemical studies, and was relieved by Kalckar’s suggestion that he take a trip to the Zoological Station at Naples. It was here he attended Maurice Wilkin’s talk on nucleic acids and observed an early X-ray photograph of DNA. After this talk, Watson knew he had to leave Copenhagen and move to a laboratory that would allow him to further investigate DNA. In this letter, Kalckar writes to C.J. Lapp at the National Research Council encouraging him to allow Watson to transfer to Cambridge.

Letter from Salvador Luria to James D. Watson
20 October 1951
Courtesy of the James D. Watson Collection

Sal Luria was crucial in getting Watson out of Copenhagen and into Cambridge. In the summer of 1951 he met John Kendrew, who then passed on the word to Max Perutz that Watson was interested in studying crystallography at the Cavendish. Watson soon met with Perutz, and with Sir Lawrence Bragg’s blessing was allowed to begin work that autumn. There was one slight problem: Watson had failed to inform the National Research Council, who was funding his research with a fellowship. In this letter Luria assures Watson that he will write to the Council on Watson’s behalf. It also includes a humorous postscript in which Luria admonishes Watson for his notoriously illegible handwriting.

Letter from Salvador Luria to Paul Weiss

20 October 1951
Courtesy of the James D. Watson Collection

Luria explains Watson’s situation in great detail to Paul Weiss (chairman of the fellowship board) in an effort to allow Watson to transfer his fellowship from Copenhagen to Cambridge. He concludes the letter by stating: “I feel Watson’s present plan, far from being a drift into the wilderness, is a considerate search for the type of preparation that may improve his usefulness to biology.” How right he was.

Letter from Paul Weiss to James D. Watson

22 October 1951
Courtesy of the James D. Watson Collection

Paul Weiss requests that Watson submits a statement outlining his plan of study at Cambridge.

Letter from James D. Watson to Paul Weiss

14 November 1951
Courtesy of the James D. Watson Collection

In his reply to Weiss, Watson begins with apologies, first for leaving Copenhagen without permission, and then for ignoring the fellowship board’s request to leave Cambridge and resume his work in Kalckar’s laboratory. Watson quickly asserts that since his collaborator (Ole Maaloe) had left Copenhagen for Caltech, there was no longer any reason for him to stay. Watson then outlines his plans: First, to work with Roy Markham on “the determination of the sequence of nucleotides in ribonucleic acid.” Secondly, he planned to study, “possible models for the general structures of nucleic acids within virus nuclear-proteins.” He justified the change in study stating, “The change in emphasis from the metabolic to the structural approach is the consequence of our belief or to be honest, our hunch, that a knowledge of the structure of nucleic acids might lead us more directly to the mechanism of replication.”

Letter from James D. Watson to C.J. Lapp
27 November 1951
Courtesy of the James D. Watson Collection

In this letter Watson gives a full account of his reasoning behind leaving Copenhagen to study the structure of nucleic acids in Cambridge. Although Watson would not receive approval from the fellowship board until January 1952, he was already in Cambridge, and had no intension to leave. Soon he would pair up with Francis Crick, one of the few people at Cambridge interested in deciphering the structure of DNA. Watson would also meet another major player in the DNA discovery, Rosalind Franklin, who gave a talk in November 1951 outlining her research into the nucleic acid. Crick had missed the talk, and unfortunately Watson had misremembered some crucial technical information regarding the water content of the DNA samples. This would result in the construction of an incorrect model and soon they would no longer be allowed to work on the DNA problem at all.

Letter from Maurice Wilkins to Francis Crick

11 December 1951
Courtesy of the Sydney Brenner Collection

In this letter Wilkins explains to Crick that the MRC Biophysics Research Unit at King’s College had decided against Watson and Crick’s proposal to continue research on nucleic acids. This occurred after Watson and Crick showed their incorrect DNA model to Franklin and Wilkins. Wilkins himself preferred that both his group at King’s and the Cavendish group continue exchanging ideas and working on the structure of DNA, but superiors at both institutions had decided otherwise.

Letter from Maurice Wilkins to Francis Crick

11 December 1951
Courtesy of the Sydney Brenner Collection

This letter was written at the same time as the previous letter, although this one is handwritten and less formal. One can assume that the typed letter was approved by John Randall, the Director of the MRC Biophysics Research Unit, and that this letter was sent “under the radar.” In this letter Wilkins describes the opposition of Randall to the collaboration and his own attempts to mediate the problem. Wilkins was ultimately unsuccessful, and it would be over a year until Watson and Crick were once again allowed to work on the DNA problem.

Letter from Crick and Watson to Maurice Wilkins
13 December 1951

Courtesy of the Sydney Brenner Collection

Watson and Crick sent back a heavily edited letter to Wilkins. There is a striking difference between the attitudes of the two parties. As Alexander Gann and Jan Witkowski explain in their Nature paper on the Crick-Wilkins letters, “the agonized tone of Wilkins’s letters and the cavalier ring of Watson and Crick’s reply, even at this low point for the Cambridge team . . . [was a] reminder that the group at King’s was already divided and dysfunctional.”

Letter from Maurice Wilkins to Francis Crick

January 1953
Courtesy of the Sydney Brenner Collection

Several events unfolded in early 1953 that set Watson and Crick on the path to deciphering the structure of DNA. Linus Pauling’s manuscript describing the incorrect “triple helix” was being circulated and Watson brought the paper to London to show Wilkins and Franklin. It was during this visit that Wilkins showed Watson the famous X-ray diffraction “Photograph 51” of B-form DNA, which clearly demonstrated a helical structure.

In this letter, Wilkins discusses an upcoming talk by Franklin, which Watson and Crick are eager to attend. Unfortunately, they were barred from the discussion because it was closed to external visitors. They would arrive two days after the talk (and after Franklin had departed King’s to join J.D. Bernal’s group at Birkbeck College), and finally see Photograph 51 for the first time. Lawrence Bragg, eager to beat Pauling to the discovery, finally allowed Watson and Crick to devote their time to DNA. Soon they would construct their famous double helix model.

Letter from Max Delbrück to James D. Watson
17 April 1953
Courtesy of the James D. Watson Collection

Max Delbrück states that he is trying get Watson an invitation to the 1953 CSH Symposium on Viruses to present the DNA structure. He also notes that Alexander Rich has an X-ray photograph of DNA that is just as good as King’s College’s.

Letter from Milislav Demerec to James D. Watson
27 April 1953
Courtesy of the James D. Watson Collection

Demerec invites Watson to present the structure of DNA, for the first time, at the 1953 CSH Symposium.

Letter from Max Delbrück to James D. Watson
1 May 1953
Courtesy of the James D. Watson Collection

In this letter Delbrück explains that, “You are invited because I swore (and Pauling seconded my oath…) that the Watson-Crick DNA structure is of basic importance in connection with at least half a dozen of the principle papers to be given at the Symposium.”