Henry Barcroft was a distinguished physiologist who greatly extended knowledge of the nervous and chemical control of the circulation in human limbs. He was also except- ionally effective in stimulating and encouraging junior colleagues, and earnt their lasting friendship and affection.
He was born in 1904. His father was Sir Joseph Barcroft, a brilliant and charismatic Cambridge physiologist from an Irish Quaker background. His maternal grandfather, Sir Robert Ball, had been Astronomer Royal of Ireland and Professor of Astronomy at Cambridge. Henry entered King's College, Cambridge, in 1923 with an exhibition, and was awarded a double first in the Tripos examinations, and research studentships that enabled him to study circulatory problems in animals for the next two years.
He spent three years at St Mary's Hospital, London, completing his medical qualification, but decided immediately to become a scientist rather than a clinician. Within the prestigious department of physiology at University College London, he resumed his earlier animal work, but was, crucially, exposed to colleagues in other departments who were extending the application of scientific investigations to human clinical problems. Many of these colleagues subsequently assumed great importance in British medicine.
After three years at UCL Barcroft was, at the age of 30, appointed in 1935 to the Dunville Chair of Physiology at Queen's University, Belfast. It was the specific hope and expectation of the university that his appointment would stimulate research in the Faculty of Medicine. It did so.
In 1935 the staffing, accommodation and equipment at Queen's were meagre. Barcroft did have the help of recent medical graduates on short-term appointment as demonstrators, but no permanent lecturer until O.G. Edholm was appointed in 1938. The teaching duties were formidable. There were 678 students in the Medical Faculty, 43 per cent of all the students in the university. Student practical classes had to be triplicated. All these problems Barcroft overcame by rugged determination, hard work and skilful planning. To free as much time as possible for research all physiology lectures were given at 9am each weekday, including Saturday.
He now turned his full attention to human physiology, using himself, healthy volunteers and willing patients as subjects, and studied the regulation of the blood flow in the limbs. He measured flow by the non-invasive method of what is known as "venous occlusion plethysmography". This method enabled observations to be made several times a minute, which allowed fluctuations in flow to be followed.
Meticulous attention to detail was essential, and measurement of recordings was laborious, but the method served. Others had used it on humans, but Barcroft, Edholm and associates refined it and used it to determine the roles of the sympathetic nervous fibres in the constriction and dilatation of the blood vessels of skin and muscle, and the actions of adrenaline and noradrenaline and other substances on these vessels. Queen's medical graduates with an interest in research were likely to turn to the department of physiology, to join the work and to submit a thesis for the MD degree.
In 1948, Barcroft was appointed to the chair at the Sherington School of Physiology at St Thomas's Hospital Medical School in London. Legend has it that he was unable to add a floor to the building because his brother- in-law Archbishop Michael Ramsey had a right to view the Palace of Westminster from Lambeth Palace. Barcroft gathered enthusiastic co-workers, and together with H.J.C. Swan wrote the first monograph of the Physiological Society: Sympathetic Control of Human Blood Vessels, published in 1953, the shortest in the society's series of over 30 monographs, is couched in simple and direct language, and illustrated by the elegantly clear diagrams that characterise all Barcroft's papers. It has stood the test of time.
In the same year Barcroft was elected to a Fellowship of the Royal Society, and in 1957 he was appointed Chairman of the Editorial Board of the Monographs of the Physiological Society. Honorary degrees at home and abroad followed, and he was later appointed as a Wellcome Trustee. Many who worked with him or came under his influence continued in active research, and occupied chairs at the Mayo Clinic and elsewhere in North America, and in Australia, as well as in the United Kingdom.
He married Dr Bridget (Biddy) Ramsey, whom he had met at Cambridge, in 1933, and they had four children, and were a happy and most hospitable family. In retirement he faced increasing arthritic immobility with unrelenting courage and determination. He also had the support of the family, especially after the death of his beloved Biddy in 1990. In recent years, long after golf and sailing became impossible, he enjoyed researching with O.L. Wade the life and work of Admiral Beaufort, who devised the numerical wind force scale.
Barcroft's 80th birthday was celebrated at a dinner of the Physiological Society, and for his 90th 45 friends, some from North America and Europe, gathered to give him a celebratory luncheon at the Royal Society of Medicine. On 7 November 1997 he attended in good cheer and spirits the last meeting the Physiological Society was to hold at St Thomas's Hospital. At this, I.C. Roddie gave a lecture celebrating Barcroft's life's work, attesting to the scientific regard and personal affection in which he was held.