Each day I would go into the walk-in incubator and look at... raise the culture vessels up to the light – there were several lights in this incubator room – to see the condition of the cells and also remove them and put them under an inverted microscope to see how the cells looked. And there... for weeks and weeks, they were beautiful. You can easily tell that they're dividing because you can actually see with the naked eye the chromosomes during the period of time that the cells are dividing, which is a good indication of their health, because they're dividing happily. And this went on at first for several months and one day I walked into the walk-in incubator, looked at a couple of cultures, held them up to the light and with some practice, you can tell by holding a culture up to the light generally how their health is, but not specifically. And I took those cultures back to my lab, put them under the inverted microscope and looked at the cells. They didn't look right.

That wasn't a shock.  It was just accepted by me because as I think I indicated earlier, the mentality at the time was that we do not know how to grow cells indefinitely as the... as the dogma said because we don't understand the constitution of their nutrient requirements fully, which is why we add 10% animal serum as a cover-up. And indeed a large fraction of the field at that time was busy determining the nutrients required by cultured cells, so it was a highlighted area in the field at that time and therefore people casually accepted, as I did, that when you saw a culture that was unhappy, it either was a result of our ignorance of how to culture them, or some technical failure.

And so I thought to myself at this point in time that perhaps the technician who was handling these cell cultures had made a mistake, perhaps the glassware was not correctly cleaned, because at that time glassware was used over and over again and the cleaning procedures were unbelievably complicated. There were pages written that were adhered to by various laboratories all over the world describing how they washed their glassware compared to other people and it was a kind of art form. So that... that was also part of the mentality of why a culture would fail. So this... upon first notice, although I made a record of it, didn't impress.