The major credit I think Jim and I deserve ... is for selecting the right problem and sticking to it. It's true that by blundering about we stumbled on gold, but the fact remains that we were looking for gold. Both of us had decided, quite independently of each other, that the central problem in molecular biology was the chemical structure of the gene. ... We could not see what the answer was, but we considered it so important that we were determined to think about it long and hard, from any relevant point of view.

Again the message to experimentalists is: Be sensible but don't be impressed too much by negative arguments. If at all possible, try it and see what turns up. Theorists almost always dislike this sort of approach.

If poly A is added to poly U, to form a double or triple helix, the combination is inactive.

For simplicity one can think of the + class as having one extra base at some point or other in the genetic message and the - class as having one too few.

A theory should not attempt to explain all the facts, because some of the facts are wrong

A comparison between the triplets tentatively deduced by these methods with the changes in amino acid sequence produced by mutation shows a fair measure of agreement.

Moreover the incorporation requires the same components needed for protein synthesis, and is inhibited by the same inhibitors. Thus the system is most unlikely to be a complete artefact and is very probably closely related to genuine protein synthesis.