I did all of these experiments with my own hands, for the simple reason that I loved the cultivation of organisms. I think I just loved the idea of growing all these strange bacteria and one of the things that I always want… I always… always found interesting to do is in fact to bring it to the stage that in fact other people can take it over and develop all the little tricks… tricks about… about handling the organisms oneself. After many of these desultory excursions I came to the conclusion that many of these sub-models were not… would not necessarily tell us the right thing, and it was at that time… it was some time later that I invented this new class of organisms. I used to say that organisms are divided into vertebrates, invertebrates, and the third class were called pervertebrates. These were organisms that were thought to be like others but were simply models of themselves. Like slime moulds is the one I did apply this to, much to the anger of the people who worked on this, who felt that they had been thereby reduced to a lower position in the hierarchy of biological investigations. I pointed out to them, position was not lower; it was just on the side. Now, nonetheless, in order to get to grips with these… with these questions, one had to begin to think of experimental models. At that time we had got a new building and what we decided is: we'll just get a whole lot of people, young people, and we'd give them the opportunity to work on this.