Of course, the most exciting things were the most difficult to work on. And halfway through my expected time at Cambridge, a specimen of pepsin came in, pepsin crystals, very beautiful crystals, from Uppsala in Sweden. They had been made by John Philpot, who was an Oxford chemist-cum-biochemist, that is to say, he wanted to read biology - poor young man - when he came up to the university, but Balliol had a very powerful chemistry tutor, who was Harold Hartley, who insisted he would, it was necessary for him to read chemistry first. But then he did get an appointment in the biochemistry lab, and could begin biochemistry, and he began by going to Scandinavia, and learning how to purify proteins with Tilselius. Well, what came out of this was pepsin, which was seen by another Cambridge friend of Bernal's, on his holiday journeys, one summer these beautiful crystals that John had made were... John was just taking out of the fridge after a holiday during which he had left them growing, and then Glenn Millikan said, well, I know a man in Cambridge who would give his eyes for those crystals. And John said, really friendly-like, well, have a tubeful, and so he put them in his shirt pocket and took them back...

[Q] And they survived?

And they survived in their mother liquor, which is the important part, scientifically, of the story.

[Q] And Bernal looked at those crystals?

He looked at those crystals, and, of course, he immediately wanted to take an X-ray photograph of them, so he raked one out of the tube with a needle onto the glass slide, and then set about mounting it on a glass fibre, which was his usual technique for arranging crystals for X-ray photography. He was a bit worried by it looking a bit shrivelled as it lay there, but he just tried the experiment of passing X-rays through it, and got almost nothing. He decided something must be wrong, and something almost had certainly... the water surrounding, the crystal had no longer water surrounding it, so he had working in the, amongst his research students, one research student, Helen Megaw, who was working on heavy water, and she was, put heavy water in lindemann glass tubes and grow a crystal inside by freezing it, and then photograph it, surrounded by the glass tube. So he borrowed some of her tubes and picked a crystal from the preparation he brought with... he got from John Philpot in its mother liquor into the glass, into the lindemann glass tube, and then sealed it up, and when he took the next photograph, it was full of reflections, rather large, blotchy reflections. I can remember it quite well, which is perhaps something, because it unfortunately seems to have disappeared since.