Maurice Wilkins by James Watson. During the second phase, 1951–52, Wilkins produced clear "B form" "X" shaped images from squid sperm, images he sent to James Watson and Francis Crick, causing Watson to write "Wilkins... has obtained extremely excellent X-ray diffraction photographs" [of DNA]. In 1953 Wilkins' colleague Rosalind Franklin instructed Raymond Gosling to hand over to Wilkins a high quality image of "B" form DNA ("Photo 51"), which she had made in 1952 but had “put it aside” as she was leaving King's College London. Wilkins showed it to Watson. This image, along with the knowledge that Linus Pauling had proposed
Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid head William Lawrence Bragg, to publish their double-helix molecular model of DNA based on data from Franklin and Wilkins. By November 1951, Watson had acquired little training in X-ray crystallography, by his own admission, and thus had not fully understood what Franklin was saying about the structural symmetry of the DNA molecule. Crick, however, knowing the Fourier transforms of Bessel functions that represent the X-ray diffraction patterns of helical structures of atoms, correctly interpreted further one of Franklin's experimental findings as indicating that DNA was most likely to be a double helix with the two polynucleotide chains running in opposite