How were we going to study the mutants? And what I'd come to the conclusion was that we'd have to do electron microscopy. Now, why was that? That was very simple: because if I wanted to see which cell was joined to another cell, I would have to look at membranes. So I'd have to look, and this is the fault of all other microscopic anatomy, they all got lost in the neuropile, they couldn't trace out the connections. But an electron microscope can resolve membranes, can resolve small things, and so we said, well, with the electron microscope you could trace the path quite... quite adequately. And what we needed to do was to do three-dimensional electron microscopy, just get all the information. Now, how were we going to do that? In a very classical mode. I had, as a student, reconstructed a brain of galago by serial sectioning of colloidal sections, and by tracing these on paper and transferring these to slices of wax, I actually made a three-dimensional model of this brain in wax with all the... the holes in it and you could open it up and look inside, and so we decided we'd have to do something like that. We'd have to cut serial sections and we'd have to go from one section to the other and trace it. Now, the electron microscope is extremely powerful, but it has a very tiny window, you can only look at a small piece of it at a time. And so to do this even on one neurone of a higher organism would be... would be impossible. That meant for one to do this on a whole organism, we would have to get something that was very, very small in order to fit it into the window of the electron microscope. And that of course was the dominant condition saying we must go to micro-metazoa, because they were small and they did fit into the window of an electron microscope.
