E. C. Noble in June 1921, and his account of the discovery of insulin.

This article concerns the events in Toronto during June 1921 that led to the discovery of insulin and the controversy that followed. It draws attention to the hitherto unnoticed participation of E. C. Noble in the early lab work on dog 386 between 17 June and 26 June 1921. None of the accounts of the discovery of insulin written by the principal discoverers, Frederick Banting, Charles Best, J. B. Collip, and J. J. R. Macleod, acknowledge Noble's participation in the lab. The fact of his participation has several implications worth noting, as they refine the history of the discovery of insulin-not the least of which is the demonstration of his credentials as a reliable witness to the lab environment in which the first successes were achieved. He remains the only participant in the discovery whose account of the insulin project has not been published; this article includes Noble's anniversary account of 1971.