By the early years of the '70s the nematode program had become established. Genetics — the basic genetics — had been done and there were now many people exploring other mutants and analysing them in the same way. The anatomy was slowly being completed, and of course many people were looking for systems that they could begin to exploit. And many people came to the lab, isolated various mutants, mapped them and then began to do complementation with them. Apart from looking at the structural changes we could analyse these mutants by putting them in combinations, the so-called analysis of epistasis. Namely if you put two mutations together and the phenotype was like A, then it meant that B had no extra effect and therefore acted after A. And so one could then analyse what came to be called genetic pathways. But the core of it, and it worried me all the time, was how on earth would one ever get down to finding the molecules involved in regulation? If there are proteins like Jacob-Monod, that recognised DNA, and if any of our mutants affected these, how on earth would we actually prove this? And although, as the muscle program was kind of the first approach to use molecular biology, it was kind of token molecular biology, that is, we would actually work with proteins. But it wasn't getting to the essence of... of the molecular basis of development.