But I went back… after this, I did another six months and finally passed medicine, but I had done research all along and published, in fact one of my papers that I published during this time involved getting down and synthesising a lot of dyes because I... I was interested in mitochondria and thought that the whole supravital staining of mitochondria was due to the oxidising enzymes there and the redox potential and so on. And so I synthesised a lot of dyes in the series… papers published, which differed… which were very similar, but differed in their redox potential and showed that only ones of these below a certain potential would be supravital stains, whereas all the others would be reduced and so bleached, and that's one of the things I did then. I also did another, which... which is an interesting experiment and which laid the basis for much of my later work, and it was a paper that showed that Claude's microsomal particles were the same as what the histologists were calling chromodial substance or ergastoplasm, which is they had to do with protein synthesis. Now I think what's interesting is the way I did this. Right, Claude had fractionated cells, these ribonucleic acid particles in an ultracentrifuge and had showed that they came to occupy a certain band in this, and they contained nucleic acid and they of course are the ribosomes as we now know them, the seat of protein synthesis. All the histologists had stained sections with dyes, of which the famous one was methyl-green pyronine, with a pyronine-stained chromodial substance or... or ergastoplasm, as it was called – red – and of course this... these were also supposed to be ribonucleic acid, but how could you tell if the particles were sub-microscopic – you couldn't see them. So what I did was: there were no ultracentrifuges, so I decided to use each cell as an ultracentrifuge and so I built a Beams and King air turbine ultracentrifuge, took pieces of liver, put them in this ultracentrifuge and spun them at this high velocity which I could get in an air driven turbine, and then cut sections of them so that each cell was like a little ultracentrifuge tube, and showed that the ergastoplasm sedimented in this cell to the same level that it did in a test-tube, above the glycogen, whatever. And there… I was very proud of that experiment... also led to something which I could write about later, the same experiment, which I published later, which was something called the Chromatic Nuclear Membrane, because I showed that there was chromatin that you couldn't spin off a nuclear membrane, which I believe is now coming back into fashion these days. But that was an interesting thing because it's the conception of translating one thing into the other…

[Q] And then you stained them, of course?

Of course, I stained them, I cut sections, I embedded them. I stained them and found a lot of things with this and incidentally I... you know, I intend to use that again in my present research to try to concentrate the ribosome or particles in a cell for in situ localisation, this is just a very old technique. Now, I published that in 1948 in the South African Journal of Medical Sciences and was actually amazed, when I went to America, that people had read this and... and found, you know… so, that I would say is my first connection with what, you know, one would say is the modern molecular biology of ask... modern cell biology of trying to ask which are the parts of the cell doing this and I still think that that wasn't histochemistry.