Predictably, Pauling’s passport trials and tribulations infuriated scientists worldwide. Sir Robert Robinson, the Nobel laureate chemist from England, wrote a letter to the London Times expressing his “consternation.” Leading American and British scientists, including physicists Enrico Fermi and Edward Teller, biologist Harold Urey, and crystallographer John Bernal, wrote letters in protest, and French biochemists elected Pauling to be the honorary president of an International Biochemical Congress scheduled to take place in Paris in July.

The international pressure eventually had an effect. When Pauling reapplied for a passport in June, the State Department overturned Shipley’s denial, and Pauling was allowed, on July 14 (Bastille Day), to travel to France and England.

In addition to its political significance, the entire passport debacle had some scientific consequences as well. Corey, who did attend the Royal Society meeting, used the opportunity to visit Franklin’s laboratory. There he was shown the superb X-ray photos she had obtained. However, he apparently did not grasp immediately the full implications of the photographs, since he did not communicate anything of significance to Pauling. Volumes of speculation have been written about what might have happened had Pauling himself been allowed to travel to see those photographs. These speculations are, in fact, quite irrelevant. Pauling had every opportunity to visit the King’s College team just ten weeks later, during the month he spent in England in the summer of 1952, and he chose not to do so. The reason was simple: Pauling was still focused on convincing everybody about the correctness of his alpha-helix model for proteins; DNA was not the main topic on his mind. As it later transpired, Franklin’s photos—in particular the soon-to-become-famous 51—contained the clear hallmarks of a double-stranded helix.

There was yet another important piece of information concerning DNA that Pauling had been made aware of but either had forgotten or at least had not internalized. This evidence was related to the bases in the nucleotides. The following anecdote demonstrates how emotional responses may interfere even with processes that are supposed to be governed by pure scientific reasoning.

The day after Christmas 1947, Pauling and his family had been on their way to Europe for Pauling’s six-month visit to Oxford. They traveled on board the famous Queen Mary. Coincidentally, Erwin Chargaff, who had been interested in nucleic acids since the war years, happened to be on board the same ship, and Pauling soon ran into him. Unfortunately, Chargaff was, in the words of biologist Alex Rich, a “very intense individual.” This did not suit Pauling, who was generally easygoing and, in this particular instance, was looking forward to a relaxing vacation. Consequently, Pauling not only paid little attention to Chargaff’s animated description of his research results but also later seemed to have ignored Chargaff’s important paper on nucleic acids. In that paper, published in 1950, Chargaff discovered a remarkable relation between the amounts of the bases in DNA. He showed that whatever the number of adenine molecules (usually abbreviated “A”) in a certain section of DNA, the number of thymine (abbreviated “T”) molecules was equal. Similarly, the number of guanine units (“G”) was equal to the number of cytosine (“C”) units. This meaningful clue to the structure of DNA—that the amount of A is equal to the amount of T, and the amount of G equals the amount of C—completely escaped Pauling’s attention. If it hadn’t, perhaps the discovery of DNA’s structure would have played out differently.