Then I started to work on drugs. What I did is I got every drug capable of curing nematodes, you know, things they fed to cattle or pigs to cure them of this, or sprayed on plants and so on. And, of course, we found that some of these paralysed the nematodes. There's a very good one called Tetramysol, which paralysed nematodes. I then found I could get resistant mutants to them, and we then developed these techniques of selecting for rare mutants by taking a petri dish and putting a few thousand nematodes on one side of it and giving some bacteria on the other side. Of course, the nematodes can smell the bacteria and know they've got to get there, but of course it's only the ones that can move will get there very efficiently. Of course, you've got to give these others a little bit of bacteria so that they segregate the mutants. And with this you could always tell if there were mutants, because we could look down on the dish and see tracks of mutants and then go round and find this one. And so we could have very, very selective... this is almost like plating out bacteria. And so we found drug-resistant mutants of various sorts and they were put into the machinery. All of this then began to... to build up and began to attract other people. In fact, some people joined us from the transfer RNA experiments.