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
Francis Crick a double helical DNA backbone. Her identification of the space group for DNA crystals revealed to Crick that the DNA strands were antiparallel, which helped Watson and Crick decide to look for DNA models with two antiparallel polynucleotide strands. In summary, Watson and Crick had three sources for Franklin's unpublished data: 1) her 1951 seminar, attended by Watson, 2) discussions with Wilkins, who worked in the same laboratory with Franklin, 3) a research progress report that was intended to promote coordination of Medical Research Council-supported laboratories. Watson, Crick, Wilkins and Franklin all worked in MRC laboratories. Crick and Watson felt