A 2001 translation of the 1951 lecture originally published in German. The translation was published with remarks by Professor Bart Hargitay, then one of Kuhn's two former student aids. Harbitay says: Before settling in Basel, Kuhn did some very fundamental work in Kiel, separating isotopes in a centrifuge. This caused him to be fascinated with the effect of countercurrents in multiplying a very small single effect to significant separations. (Journal of the American Society of Nephrology website)
