And I think the main new thing that came out of our work was that these digestive systems do not exist – only in eating cells, in cells that are professionally involved, like macrophages or white blood cells – in the uptake and destruction of foreign bacteria... foreign materials in general. But that every cell type, even nerve cells and muscle cells, have a digestive system, have lysosomes. And so this really led to the discovery that what in the original protozoa was essentially a function connected with feeding, and digesting of food had been converted into higher organisms into all kinds of different functions. This basic digestive function, the function of taking up, really had specialised functions in different cell types. In the kidney they would be involved in the uptake and digestion of proteins that have passed through the filter in the tubules of the kidney. And so on – in the liver it would be different, in the... in the thyroid lysosomes would be involved in the digestion of thyroxine, the thyroid hormone from the thyroid globulin, and so on and so on. And then the more general function was also discovered, which was important even for cells like muscle cells or nerve cells that hardly are involved in taking up foreign materials and this is a function which I didn't discover but I called it autophagy. I invented a few words in my life; that's probably, again, my classical education. And autophagy is a self-eating by cells – it's a mechanism whereby small bits of the cell are segregated... it's a complex mechanism... are segregated within a membrane and then conveyed to lysosomes for breakdown. So this is autophagy; self-eating is one of the mechanisms whereby cells degrade their own substance and replace it, so it's part of turnover. So autophagy is involved even in cells that do not... do not carry out any sort of endocytosis.