I can tell you one other epiphany. Having the business of the cleavage is one sort of... minor... The one of the Bence Jones protein is pretty impressive. The third one, which came with the help of my fellow scientists, was: when we had the whole structure, I disappeared in a room with some poppit beads, child's beads that... these little round plastic beads that hook into each other to make a chain, and some piano wire, and a frame you use usually to erect organic chemical reaction – sort of like the thing supporting the lights here – and after about two days, and my colleagues thought I was nuts, I had built a chain model of the antibody molecule. And of course it wasn't like what you really see when they finally did the X-ray but it was enough to do something really very satisfying, and I have to speak to that... sometimes you're lucky when you mean actually... put luck it... not important, just about four thirds. What was lucky was that the antibody problem was so severely constrained that once you saw that Macfarlane Burnet's theory was correct, and once you saw the structure, you could answer a huge number of questions that people were never able to answer. For example: what part of the molecule bound to the antigen?

Well, here Porter did something very remarkable because he cleaved the molecule by cutting the chains – instead of breaking the disulphide bonds he broke the chains themselves – and he got one part that bound the antigen and another part that happened to crystallize, that is in fact, we showed, responsible for the other functions of antibodies. So in short order what we got was a picture of a molecule that had these domains that had variable domains in the light and heavy chains, where the sequence changed, and which was accounting for why each myeloma protein antibody was different from the other, and constant domains, and we could actually... I think it was really one of the first proteins if not the first where domain structure was shown. And I'll come back to that because it's an important genetic problem, and you as a geneticist would realize this. Well, we could then assign to each domain a particular function, and then we could even hook the molecule and see how it was hooked up to the cell, and you'll remember that it was one cell, one antibody, and that if... and this generated the next question... if each antibody was different, how did they become different. Well, it turned out that here was a problem that Joe Gally and I worked on theoretically.