So back to the H2. I did my work on two levels. One was the somatic level, which was based on the variant selection model. And the other was... I decided to do a straightforward classical Mendelian genetics on the H2 system to look for a recombinance. It looked like it's not a single gene - that it might be multiple genes, or that there was an intragenic recombination in the H2. So I began to look for such recombinants and was getting... I was not the first... there were before Snell and his co-workers, Stimpfling and Gorer, and others, but as you will realize later the recombinants I got were then essential for some of the studies that followed later by myself and by other people. So in terms of the... at the somatic level I... the main result I was getting was that there were many antigens by that time known in the H2 system already. And the question was, was each of these antigens specified by a different gene? Or did some of the genes specify multiple antigens? And so I was taking one of these antigens after the other and asking can I delete one of these antigens without affecting the others? Which would indicate that it's separate... on a separate molecule and perhaps a separate gene. Or if I delete one will the others go with it? I don't want to go into any details... the end result was that some of the... most of the antigens you could not delete alone, but some of them you could delete together while others would remain. The... basically it appeared that there were two regions in the H2 genetic segment. One so-called K and the other D, they were just called by the antigens, and that you can delete them separately. The K with all the whole entourage of other antigens you can delete as a single unit while the other unit, the D, will be untouched. The same thing you could do in the reciprocal way. So it appeared like there were two parts of the H2 segment in this.

So this is as far as I brought it. I was awarded a PhD degree in 1964, I think, and in that... by that time I was more interested... I didn't feel like that project will lead too far. I mean there was... whatever could be done I thought I did and I didn't how... how to... how I can do more. But the H2 itself began to attract me very much. I mean here was an example of something that seemed like it was complex genetically and it was very exciting to find out what does the complexity mean. There was no, in mammals, no other system, no what... how are genes organised? Or what do they... in cases of blood groups, for instance, what is the relationship between the antigen and the genes?