Francis Crick DNA crystals revealed to Crick that the two DNA strands were antiparallel. In January 1953, Watson was shown an X-ray photograph of B-DNA (called photograph 51), by Wilkins. Wilkins had been given photograph 51 by Rosalind Franklin's Ph.D. student Raymond Gosling. Wilkins and Gosling had worked together in the Medical Research Council's (MRC) Biophysics Unit before director John Randall appointed Franklin to take over both DNA diffraction work and guidance of Gosling's thesis. It appears that Randall did not communicate effectively with them about Franklin's appointment, contributing to confusion and friction between Wilkins and Franklin. In the middle of February
DNA coworkers Colin MacLeod and Maclyn McCarty, identified DNA as the transforming principle, supporting Griffith's suggestion (Avery–MacLeod–McCarty experiment). DNA's role in heredity was confirmed in 1952 when Alfred Hershey and Martha Chase in the Hershey–Chase experiment showed that DNA is the genetic material of the T2 phage. Late in 1951, Francis Crick started working with James Watson at the Cavendish Laboratory within the University of Cambridge. In 1953, Watson and Crick suggested what is now accepted as the first correct double-helix model of DNA structure in the journal "Nature". Their double-helix, molecular model of DNA was then based on one X-ray