Joseph Barcroft was a highly distinguished physiologist of international repute, whose scientific interests were of wide range, but principally centred on respiratory functions, studies relating to blood, aspects of nutrition, and aspects of foetal development. He was also known for rather fearlessly experimenting on himself.

Barcroft was born in his parents' house, The Glen, Newry, the second of the five children of Henry Barcroft, linen merchant and inventor, and Anna Richardson Malcolmson, of the well-known Richardson family of linen producers. Both parents were Quakers, the family religion since the 1660s (the Barcroft family line can be traced to before the Norman Conquest). Henry's maternal great-uncle, John Grubb Richardson, had acquired The Glen for the newly-wed couple at the same time as appointing Henry a Director of the Friends' industrial village which he had recently set up at nearby Bessbrook.

Barcroft (widely known as "JB") received his early schooling at home until he was twelve. He had two tutors: Miss Day, later principal of Ladies' Intermediate School, Trevor Hill, Newry, taught him arithmetic and Latin, and Miss Barritt, a Quaker from Croydon, who was a resident governess (The Glen was a house of considerable size) who taught him science subjects.  The young boy's exercise books and test-papers survived many decades and display considerable scientific and mechanical learning, perhaps not surprising given his father's bent for things mechanical, though less than a precocious aptitude for spelling.

In 1884 he was sent to the Quaker Bootham School, in the city of York, where he was encouraged by several teachers in his growing interest in sciences; similarly, from 1888 as a pupil at the relatively new (Methodist) Leys School, Cambridge, the headmaster, Reverend Doctor W.F. Moulton, was so encouraging of Barcroft that he allowed him to matriculate at the University of London, in January 1889, in order to sit for the BSc degree, which he obtained in 1891. This degree had been in existence for around 30 years; though records are not entirely clear, Barcroft seems to have been the first to be awarded the degree while still at school. However, the effort required for this considerable achievement apparently affected his health to such an extent that he then took a year off study. While at Leys he was Secretary of the Missionary and Literary Societies, and won his "colours" (that is, represented the school) at cricket, playing on the second eleven. Ever the experimenter, when batting he held the bat not by its handle, for which it was designed, but halfway down the blade. Despite his limited athletic prowess, he nevertheless was also a keen rider, sailor, skater, tennis player and, particularly, golfer. His father laid out a nine-hole course at The Glen, of which the son made considerable use, developing a passion for the game which continued throughout his life. He was tempted to follow hounds, but, whereas in Ireland this was widely pursued, the disapproval shown in the Barcrofts' Quaker milieu served to make him demur at the activity.

During this time he was a frequent passenger across the Irish Sea, always travelling through the port of Greenore, in County Louth, at the eastern end of Carlingford Lough, which on its northern shore washes County Down. He befriended many of the ferry captains, who would welcome him on the bridge. Barcroft remained attached to Carlingford Lough and its surroundings all his life. He spent part of his honeymoon there and frequently enjoyed yachting on the Lough. He was also a keen and, apparently, accomplished painter in watercolours; his marked preference for seascapes - very possibly inspired by his Carlingford background - remained, according to his wife, marked throughout his life. Often on his trips home to Ireland, he would visit his relatives at Moyallon, County Armagh, residence of his great-uncle John Grubb Richardson. One of these relatives described him in glowing terms: she highlighted his charm, as well as his attractiveness in looks and manner.

Following his "convalescing" year which he spent at home in Ulster, Barcroft went up to King's College, Cambridge, to read for the natural sciences tripos, as Prizeman and Exhibitioner, obtaining first-class honours in part one of the tripos in 1896, and part two (physiology) in 1897. Though it was fairly early on in his undergraduate studies that he took up the interest in physiology which would his life's work, he had nevertheless displayed his catholic scientific interests when he appeared before the Belfast Natural and Philosophical Society on 7^th January, 1895 to give a paper on the properties of the surface of liquids. This lecture would become the first of over 300 papers he would publish in his lifetime. His wider scientific interests were also displayed when he gave what some claimed was the first (if not, it was probably the second) demonstration of Röntgen's new X-ray photography in the United Kingdom, early in 1896.  

Barcroft began a research programme in the Cambridge Physiological Laboratory in 1897 and continued this, with occasional interruptions, throughout his entire life. His first interest was in blood gases, and his early work in this field led to a lifelong interest in haemoglobin, and particularly its combination with oxygen; he was awarded the Walsingham Medal in 1899 and a prize fellowship and appointed lecturer at King's College. Aspects in his preferred field which he studied included the effects of temperature, carbon dioxide pressure, acidity, salts, dialysis, diet and exercise and high altitude; for the latter, he participated in high-altitude expeditions, in Tenerife in 1910 and at Monte Rosa, Italy in 1911. These studies on haemoglobin were synthesised in his widely-acclaimed book The Respiratory Function of the Blood (1914) and regarding the second expedition, was supplemented by information gleaned from studies at Carlingford on one of his many trips back to Ireland.

He attempted in 1902 to settle in Belfast, applying for the Dunville Chair of Physiology at Queens College, Belfast. Despite his record and a glowing encomium from the highly distinguished physiologist Professor Angelo Mosso, Barcroft was passed over for the post, which was awarded to TH Milroy of Edinburgh; on his retirement in 1935 he would be succeeded by Barcroft's elder son (see below). Also in 1902 the annual meeting of the British Association for the Advancement of Science took place in Belfast. Both Joseph Barcroft and his father, Henry, joined the Association at this meeting; furthermore, Joseph was one of the secretaries for Section I (Physiology). Barcroft would have close links to the Association throughout his career. On 15^th September he gave a paper to the Belfast meeting, later published.

On the outbreak of the First World War, Barcroft, as a practising Quaker, might have been expected to have refused any military service. However, he went against the local Cambridge Meeting of the Society of Friends (though he never formally resigned) by writing to the War Office offering any assistance they might request, basing this decision on the parable of the Good Samaritan, who did not wish "to pass by on the other side". Initially he was asked to remain where he was, and continued to correspond through colleagues in neutral countries with German scientists with whom he had worked before the wars. However, in April 1915, after the second battle of Ypres, which saw the first poison gas attacks, Barcroft with his extensive knowledge of problems arising from oxygen deprivation, soon found himself called upon to cross the channel to examine the effects of gas poisoning. At Boulogne, he came across Almroth Wright, the bacteriologist, Belfast educated (at the Royal Belfast Academical Institution), who had established a treatment and research centre in Boulogne Casino, and in whose laboratories his junior, Alexander Fleming, would later discover penicillin.

Throughout the war, Barcroft carried on his work both at Cambridge and at the government's chemical warfare station at Porton Down where he eventually became Chief Physiologist. During his time at Porton Down Barcroft took part in one enterprising experiment, when, characteristically, he exposed himself, along with a dog, to hydrocyanic acid in a closed chamber. The animal nearly died, but Barcroft was unaffected, which demonstrated of how different species vary in their responses to toxic gases. He was appointed CBE (a civilian honour) in 1918 for his services during the war.

He returned to Cambridge as Reader, later becoming Fullerian Professor of Physiology at the Royal Institution (1923) and Professor of Physiology at Cambridge (1926), and developed his interest in high-altitude physiology, in particular, whether the lungs actively secreted oxygen, as had been claimed by some scientists before the war. Barcroft tested this in a famous experiment in 1920, when he placed himself in a glass box for six days, while the oxygen concentration was gradually reduced until it was equivalent to the oxygen pressure at a very high altitude. Blood was drawn from his radial artery using the newly developed technique of arterial cannulation, and there was a dramatic moment when the first blood came out blue rather than red, indicating that oxygen secretion by the lungs was not occurring. Subsequent careful measurements confirmed this.

In 1921-2 Barcroft led a high-altitude expedition to Cerro de Pasco in Peru, to study pulmonary gas exchange, blood biochemistry, and several other topics. These high-altitude interests culminated in "Lessons from high altitudes", the first part of the second edition of The Respiratory Function of the Blood, which was published in 1925 and earned wide acclaim. Barcroft was appointed Professor of Physiology at Cambridge the same year. Another area in his research involved work on the storage organs of the blood, particularly the spleen. During this time Barcroft organised a substantial extension of the Cambridge Physiological Laboratory, with the result that it became one of the most impressive physiological institutions in the country. He visited the United States, and gave a series of lectures to the Harvard Medical School, published in 1934 as Features in the Architecture of Physiological Functions, acclaimed for the breadth of its scholarship.

His final period of research focused on foetal physiology, including blood volume, placental blood flow, the physiology of the foetal heart, both foetal and maternal haemoglobin, and metabolism and growth in utero. This work he brought together in Researches in Pre-Natal Life, the first volume of which was published shortly before his death in 1947.

Barcroft was elected Fellow of the Royal Society in 1910 and knighted in 1935. He delivered the Croonian lecture to the Royal Society in the same year, and the Linacre lecture at Cambridge in 1941. By this time he was head of the Agricultural Research Council unit in animal physiology at Cambridge. In 1943 he was awarded the Copley medal of the Royal Society; he had already won its Royal Medal in 1922. His honorary degrees included doctorates from Queen's University, Belfast, (DSc, 1931), the National University of Ireland (DSC, 1933; the parchment was signed by Eamonn de Valera, as President of the University, and a fellow recipient was TH Milroy, his rival for the Dunville Chair in 1902), Harvard (1936) and Dublin (1937). In 1952 Mount Barcroft, a "Thirteener" peak in the White Mountains, California, was named in his honour.

In 1903 Barcroft married Mary Agnetta ("Minnie") Ball (1875-1962), daughter of the Dublin-born astronomer Sir Robert Ball, sometime Astronomer Royal of Ireland and Professor of Astronomy at Cambridge. They had two sons, one of whom, physiologist Henry Barcroft FRS, was appointed to the same Dunville Chair at Queen's University, Belfast which his father had failed to secure in 1902.

Barcroft died suddenly of a heart attack, in Cambridge.

Born:	26 July 1872
Died:	21 March 1947