If it had not been for John Randall’s creation of an MRC Research Unit dedicated to the study of the physical and biological mechanisms of single cell division, the structure of DNA would not have been revealed in the U.K. Most likely it would have been discovered in Linus Pauling’s laboratories in America.
Today, if you asked who discovered the structure of DNA, the response should be: Watson and Crick building atomic models in Cambridge and Wilkins and Franklin et al., exploring x-ray diffraction patterns at Kings College in London.
Randall held the Wheatstone chair of physics and was director of the MRC unit, funded in perpetuity with the avowed intent of applying “The Logi of Physics to the Graphi of Biology”—in particular to the mechanisms causing division of living cells.
In the 1940s it was still being debated as whether it was the nuclear protein, the DNA or both together that were instigating cell division. Randall was convinced by the work of Avery and others that DNA alone was the agent of division. Accordingly he had several avenues of research progressing in his laboratory concerned solely with DNA.
Knowing that sperm heads were closely packed with DNA, he had directed me, as his Ph.D. student, to make flat flakes of rams’ sperm and expose them to x-rays, edge on, in the hope that the resulting diffraction pattern would reveal something of their DNA structure. The result was a disappointing, fuzzy fiber diagram.
Meanwhile Maurice Wilkins had attended a lecture at the Royal Society by Rudolf Signer, a Swiss biochemist who had managed to extract DNA from calf thymus gland at a very high molecular weight—around 12 million.
At the end of his lecture, Signer offered some freeze-dried samples of this sodium salt of the DNA, which Wilkins quickly accepted. Back in the lab he found that fibers drawn from a water gel of this material were highly birefringent. I asked him if I could try to get a diffraction pattern from a specimen of these fibers to compare as a gold standard with those from my various attempts to persuade rams’ sperm to lie flat.
So Wilkins pulled the fibers varying from 5–10 µ in diameter and I wound them onto a paper clip. Testing the first specimen of 35 fibers with an x-ray machine produced a result not much better than my sperm flakes. This should not have been surprising since most of the atoms in the fibers were the same as the air within the camera. The next step was to displace the air with hydrogen.