I was searching for a cell adhesion molecule, and I remember working with a Chinese post-doctoral student who never wrote anything in his notebooks but scribbled things on post-its and threw them around the lab – that was the striking set of events. And we had devised a sort of assay: how would we find out how one molecule was responsible for sticking one cell together with another? What we decided to do is make an antibody against the surface antibodies, against the surface molecules of a cell, and then search for fractions from the cell that would inhibit the antibody, and that must have been the one that blocked the... the adhesion molecule. Well, for a year and a half it was a totally vain search, and then one day, the serum from a set of an animal that was the worst possible protocol you could ever use which would have been thrown out of a grant right away – that one came out positive, and we discovered the neural cell adhesion molecule which linked all the cells of the retina together from chicks... from chick embryos. At that point an explosion occurred in our lab, by the way. We would have a thousand chick embryos, lots of eggs, so the whole place looked like a chicken farm... I mean, no, the early part of a chicken farm. I guess in a chicken farm you don't do that: if the egg has an embryo you throw it out. But whatever is the case. We got very, very excited and we found this molecule.

Now, I have to stop and tell you another story. I was invited to go to the University of Rochester to talk about this. That often happens, you know; in those days it happened when you had some announcement of some singularity and I'd just published our first paper. And I got up and I said, 'Okay, this is going to be about cell adhesion molecules and the molecular structure of one which I think opens up a whole new vista, but this really isn't as important as the first work in the field, which was done by a very great embryologist, Holtfreter, who's dead now and no longer with us, but he showed that you could pull apart all the three germ layers of an early embryo, stir them up, and they'd recombine in such a way that you get the layers back again... an incredible experiment.' And then I went on and I gave my lecture about how it's mediated by this NCAM, the Neural Cell Adhesion Molecule. At the end of the lecture an old man who was partially blind came up to me and said, 'I'm Holtfreter.' And I said, 'Well, sir...' I tried to mitigate my error. I said. 'All great men are dead aren't they?' And we became friends and we talked about... he told me about his experience.