I was starting work on what's now called peripheral tolerance, on making animals tolerant of antigens which are injected and reach cells after they've left the thymus. Right. What's now called T-cell after they've left the thymus. And that was part of what I'm sure was the best work in my life, over the next 10 years. And that was made possible because, having been- having messed around with this radio chromium in chickens in Edinburgh in a way which I would be sent to prison if I did now. I mean the chickens were running around and God knows what's happening to the chicken shit at the end of all this. I arrived in Mill Hill where there was a radiation safety officer who was actually extremely helpful and gave lots of good advice. And under his, sort of, with help from him, and especially with help from Rosalind Pitt-Rivers, I was able, along with other people, Americans and many other people in the world, particularly from the group then in Pittsburgh. Bill Weigle was a working- was a main workman, but they also had introduced the use of isotopes for detecting antibodies and if you want to work with mice, working the way that Peter Gorer had done before, with antibodies against red cells, where you need a special media and reagents to test then, wasn't at all attractive. Starting work with protein became much easier. I actually- Now I come to think of it, that work had started before in Edinburgh where my first research student, David Dresser had discovered that if you injected radio iodine labelled proteins- foreign immunoglobulin into a mouse, that was- that could do one of two things. It could either be eliminated in the way that the cells had been eliminated, that's to say that the protein circulated in the mouse for three or four days without being eliminated, then it would quickly clear, apparently by antibody, or it could also be given radioactivity and the radioactivity would survive forever. And that depended on whether adjuvants had been given. If the protein was given without adjuvants, then it induced tolerance in an adult mouse, but if it was given with adjuvants, then you got this- That's what we now know as a microbial molecule that stimulates the immune system. The adjuvant- The adjuvant. Right. Right. Right. No adjuvant, no immune response, basically. Exactly. But if you give it without it then you tolerise the mice. And that began a very productive 10, 15 years. That's right. That's right.