One of the first things that happened was I was in... having read about McCulloch and Pitts and starting to read about the nervous system, I found a laboratory where people were working on nerves. And this was run by a professor named John Welsh at Harvard. And... it’s a nice story because the Harvard Biological Laboratory is a huge building and this building was new at this time. We’re talking about 1949 or... it must have been '48 or '49. So, the building was two thirds finished and almost empty. So, I encountered this Professor Welsh and said I was interested in learning more about nerves and things like that. And he said: 'Well, we do a lot of experiments with invertebrate nervous systems and we’re... we're interested in how the crayfish claw works.' It’s a little arm. The joints of the arm are tetrahedra. They’re sort of hinged this way and then at right angles. The next hinge is this way and the next one is this way. And that’s the anatomy of the mechanical arm I built that you see in the MIT Museum today. It's... the joints are modelled on the joints of the crayfish claw. But anyway, Dr Welsh said: 'The interesting thing about this crayfish claw is that it’s so easy to get at the nerves because...' he took out a crayfish and he said: 'You just break the limb off like this and pull it just like this and there’s this little transparent thread sticking out.' And it’s right there and you can see it with the naked eye and it consists of five nerves. And with a magnifying glass you can... and a needle, you can separate the five nerves. And one of them is an inhibitor nerve, so that if you stimulate with this nerve, the claw will close. Or, if you stimulate another nerve, it’ll move here but... you find the one that causes the claw to open and close. And then if you stimulate this other one, which is smaller, that’s the inhibitor nerve, it’ll open again even... so, I arranged a set of five switches and batteries or something – no, they must have been AC things – so that I could mount this crayfish claw here and the five nerves are connected to these five switches and... actually, I had it on potentiometers so you could vary the signal.

And after a couple of days, I got this thing arranged so I could get the crayfish claw to reach down and pick up a pencil and pick it up again. And... John Welsh called all the other biologists in and said: 'Look at this' and...  I was interested that they were so interested because... it seemed like such an obvious thing to do. So, he also... and you could get new crayfish every day because somebody drove up to some lake and... nearby and got them. And then, he also had me do some experiments with turtle hearts. And I don’t remember what these experiments were, but the main thing is that if you irrigate these things with cold water... these invertebrates are wonderful because these are cold blooded animals. And the turtle heart will work for a week if you just run Ringer’s solution through it and you can do really complicated experiments with almost no equipment.