“I am just putting the final touches”: Letter from Linus Pauling to Peter Pauling on March 27, 1953. At http://osulibrary.orst.edu/specialcollections/coll/pauling/dna/corr/sci9.001.33-lp-peterpauling19530327.html.

Extensive studies by Swedish researchers: In the context of the Betula Project (a research project on human memory), psychologist Lars-Göran Nilsson and his colleagues gave many memory tests to people in the age range thirty-five to eighty, and repeated tests at one-year intervals. The project started in 1988, and the researchers studied a total of 4,200 individuals. A collection of articles describing many of the results is Bäckman and Nyberg 2010.

I asked molecular biologist: Conversation on April 18, 2011. Jack Szostak, Nobel laureate in Physiology or Medicine, whom I also asked about Pauling’s chemistry failure, also suggested that Pauling might have thought that he would find a way for the structure to work from a chemical perspective.

“We have also been stimulated”: Watson and Crick 1953a.

The dark cross was the unmistakable: Moreover, the spacing between successive dark spots indicates the distance covered by a complete turn of the helix (found to be 34 angstroms), and the distance between the center of the X shape (figure 14) to the top indicates the distance between successive bases.