Foster was a true scholar, a scientist who worked among medical academics in fields which ranged from early work in classical botany and moved through mammalian cell biology to molecular cell biology. He was also a respected teacher, remembered with gratitude and affection by former students and researchers.
Charles Foster seemed destined for experimental science from an early age. As a child, as well as a chemistry set (producing hydrogen, which exploded) his parents bought him a small compound microscope. The 13-year- old Foster was fascinated by ciliates (protozoa with hair-like lashes) which he had discovered for himself gliding in the flower-vase water. He bought a Guide to Protozoa from the Natural History Museum, read it at night and learned their names - Euptotes, Loxodes, and so on. From then on he was determined to be a biologist interested in cells.
He was educated at St Olave's Grammar School then went to University College London, as a Marshall Scholar, to do a BSc in Botany with T.D. Hill and Professor Sir Edward Salisbury - a most stimulating department. His MSc research was on "Sub-cellular Elements in Bulgaria inquinans" (a fungus known as "witches' butter") and in 1938 he joined the Middlesex Medical School, working with Professor J.H. Woodger, the eminent theoretical biologist.
During the Medical School's wartime evacuation to Leeds, Foster began working on the pituitary. He continued mammalian work at the Middlesex and was much influenced by Woodger, who taught a stringent approach to problems and also took Foster to study weekends with Karl Popper and Peter Medawar.
With a PhD in animal cytology Foster moved to St Mary's Hospital Medical School in 1947 to teach biology. Rather shy himself, he found it formidable to lunch with Sir Alexander Fleming, who was shy with strangers and limited his remarks to "yup" and "nope".
Foster's research was mainly in endocrine studies and he was a long-standing member of the Society for Endocrinology. He published many papers on the pituitary in Nature, the Journal of Endocrinology and Quarterly Journal of Microscopical Science, and was awarded a London University doctorate of science for this work. These were studies investigating, for example, the changes in the pituitary cells associated with events in reproduction - coitus, pregnancy and lactation (in the rabbit) - to help work out which cells produced the controlling hormones that acted on the target glands, e.g. causing mammary glands to produce milk.
In the 1970s he worked on Tamm Horsfall glycoprotein in the kidney and was most grateful to Professor Richard Creese and Professor Charles Michel at St Mary's, who enabled him to continue research and publishing in the 1980s, even after he had retired from his post in the Medical School.
Foster regarded the teaching of "real" cell biology as his major achievement, particularly the intercalated BSc units he initiated at St Mary's which produced successful science-based medical researchers. His students worked with live cells, such as tissue cultures of Xenopus (the clawed toad) and used phase contrast-cine and electron microscopes as well as learning histochemistry (the chemistry of living tissues). They visited other research institutes and received a serious grounding in scientific method.
He also brought his students scholarly attitudes to learning and life, which were introduced into practical classes and long discussions after class - about mutual interests in music, poetry, art, Italy, the origins of ideas and arcane natural history such as the constant movement of the Telegraph Plant (Desmodium gyrans). Students' interest in biology was aroused by his charisma, zest and warm enthusiasm. One former student said, "He gave us a grounding in integrity, so fundamental to medical education." Another (now a Professor and FRS) admitted he still had Foster's copy of John Donne's poems on "long-term loan".
Charles Foster's achievements show the necessity for sympathetic "interpreters" of science for the future development of medical research, but they are unlikely to travel such a long road, from classical botany to molecular cell biology techniques, as he did.
Charles Foster did not leave St Mary's on his retirement from the Chair of Cell Biology in 1979 but moved downstairs into the Department of Physiology and Biophysics, writes Charles Michel.
There he spent more than 10 years continuing research in collaboration with Pauline Alexander and Hubert Britton, first on attempting to discover the cells in the kidney responsible for the secretion of Tamm Horsfall glycoprotein, and later on atrial natriuretic peptide, a hormone discovered by a Canadian research team in the early 1980s, which is released from cells in the heart and controls, among other things, the volume of the blood.
Foster's real contributions during this period were more cultural and social. Both within the department and in the Medical School he befriended new research students, post- doctoral fellows and lecturers, winning their confidence, while encouraging them to take a broader view of science, philosophy and the arts.
A quietly contented man, Foster was most fortunate in his second marriage in 1976 to his colleague Dr Anne Maddocks, who not only gave him support and affection but shared his expertise for botanising, and his enthusiasms for music, painting and Italy.
Charles Lewis Foster, cell biologist and botanist: born 2 September 1912; Demonstrator, then Lecturer in Biology and Histology, Middlesex Hospital Medical School 1938-47; Lecturer in Biology, St Mary's Hospital Medical School 1947-48, Reader in Biology 1948-69, Professor of Cell Biology and Histology 1969-79 (Emeritus); married 1949 Margaret Woodward (died 1973, two daughters); married 1976 Anne Maddocks; died 27 September 1995.