The cell biologist Henry Harris, who has died aged 89, made the key discovery that the inactivated form of a virus responsible for a respiratory tract infection in mice could fuse cells together very efficiently, even when they differed widely in type and species of origin. He showed that this remarkable finding could be exploited to reveal how the expression of genes was controlled, how they could be assigned to specific chromosomes and, of central interest to his later research, that some could suppress the growth of cancer cells. Fusion produces either single large nondividing cells containing multiple separate nuclei of each type or, most interestingly, hybrid cells in which all genes of the participants are encompassed within a single common nucleus. The hybrids are of particular value in showing sustained growth and division, and in tending to shed chromosomes more or less at random. In elegant experiments in which he made such hybrids between cancer cells and their normal counterparts, Henry found that malignancy was consistently suppressed, only to re-emerge later among some of the descendants of the hybrid cells. He was able to correlate the recrudescence of malignancy with loss of a specific chromosome of the normal partner cell. This provided the first clear evidence for the existence of a class of tumour suppressor genes. By using x-rays and later harnessing DNA technology, he was eventually able to identify a gene capable of suppressing a wide range of malignancies; it produced a type of collagen that is deposited in the material in which many types of cells are embedded. Cell fusion has also proved to be of clinical value, with the development of monoclonal antibodies for treating an increasing number of diseases. Henry's scientific achievements were recognised by his election as a fellow of the Royal Society in 1968 and the award of a knighthood in 1993. Born in Russia, Henry was the son of Jewish parents, Sam and Ann. In 1929 the family emigrated to Australia. From Sydney Boys high school, Henry went to the University of Sydney to study modern languages. On graduating in 1944, he embarked on a medical degree inspired, he claimed, by the works of literary doctors, in an attempt to become a latter-day Chekhov. He began to dabble in experiments during his medical training, and this developed into an obsession with basic biomedical research that captivated him for the rest of his life. When he qualified as a doctor in 1950, he married Alexandra Brodsky, also of Russian Jewish origin, whose family had gone to Australia from Belgium after the second world war. Thereafter, he won a scholarship to take a DPhil degree at the Sir William Dunn School of Pathology, Oxford University, under the supervision of a fellow Australian, Professor Howard Florey, who led the team that had earlier demonstrated the clinical efficacy of penicillin. Once Henry had gained his DPhil (1954), he became director of research for the British Empire Cancer Campaign at the Dunn School. After a year in the US (1959-60) and three as head of cell biology at the John Innes Institute at Bayfordbury, Hertfordshire (1960-63), he returned to the Dunn School as professor of pathology, in succession to Florey. He continued to head the Dunn School after being appointed regius professor of medicine in 1979, and carried on working in the department for some years after retiring in 1992. Throughout his career, he undertook much of the experimental work with his own hands, seldom attending conferences and strictly limiting other engagements that would interfere with his research. He also adopted various measures to minimise the burden of other duties on members of staff who were active in research, including recruiting distinguished retirees to help with the preclinical teaching of bacteriology and virology. Henry had a deep feeling for history, both within the biological sciences and more generally. It gave him great satisfaction that when Henry VIII established the regius chair of medicine he chose to link it with the mastership of the almshouses in the medieval Oxfordshire village of Ewelme, which were founded by Geoffrey Chaucer's granddaughter, Alice, and her husband, Thomas de la Pole, Duke of Suffolk, and are still in existence. He appreciated the Dunn School for its unusual elegance and setting as a laboratory, and fought successfully against the university's repeated attempts to destroy its gardens for car parking. Henry's writings after retirement included a book offering novel insight into the history of discovery of the cell, The Birth of the Cell (1999), and another, Things Come to Life (2002), which traced the history of the notion that living creatures could arise spontaneously from nonliving material, and described just how difficult it was to design experiments to disprove the idea. He also produced a masterly translation of a book on cancer written a century ago by the great German embryologist Theodor Boveri (2008). Moreover, both before and after retiring, he wrote engaging short stories about academic life for the Oxford Magazine, which were brought together in Remnants of a Quiet Life (2006). He is survived by Alexandra, his son, Paul, and daughters, Helen and Ann. Henry Harris, cell biologist, born 28 January 1925; died 31 October 2014