The lysosome turns fifty

In the course of an investigation aimed at characterizing hepatic glucose 6- phosphatase, the unrelated acid phosphatase of rat liver was serendipitously observed to be latent and particle- bound in freshly prepared homogenates. Experiments designed to elucidate this intriguing finding led, 50 years ago, to the discovery of lysosomes. This could not have happened if strict adherence to a previously set programme had been mandatory.