LEONARD DONCASTER'S death from sarcoma at the age of forty-two has stopped a career of exceptional distinction. When I lately saw him, apparently in his usual health, presiding over his laboratory as the newly elected Derby professor of zoology at Liverpool, I had comfort in the thought that by his appointment a fresh centre of genetics was safely begun. Doncaster was a natural investigator. From his student days there was never a doubt as to the purpose of his life. The problems of biology were always in his mind. For him the materials were everywhere. Though circumstances led him into academic zoology, he was an excellent field entomologist and botanist, with a fair knowledge also of the domesticated forms. Latterly he became more and more drawn towards cytological methods, but he always kept in touch with the other lines, knowing that the next advance may begin anywhere.