Hodgkin, Dorothy Mary Crowfoot
(19101994), chemist and crystallographer
, was born on 12 May 1910 in Guizeh, near Cairo, Egypt, the eldest of four daughters of John Winter Crowfoot (18731958) and his wife, Grace Mary (Molly) Hood (18771957). Her father was an inspector with the ministry of public instruction for Egypt and the Sudan, but he also developed considerable expertise as an archaeologist, and later became director of the British School of Archaeology in Jerusalem. Her mother, although largely self-educated, shared her husband's interest and became an authority on ancient textiles in her own right. Both were descended from moderately prosperous families. The Crowfoots came from Beccles in Suffolk, where many of John Crowfoot's relatives entered the medical profession, although his own father had taken holy orders and eventually became chancellor of Lincoln Cathedral. The Hoods owned the small estate of Nettleham Hall, near Lincoln.
Early years and education
Until the outbreak of the First World War Dorothy and her next two sisters, Joan and Elisabeth, lived in Cairo with their parents, returning to England for three months each year to escape the summer heat. In 1914 their mother left the girls in the care of their nurse at a house near to their Crowfoot grandparents, who had retired to Worthing in Sussex. She and her husband stayed in Cairo and Khartoum throughout the war; John Crowfoot was appointed director of education for the Sudan in 1916. After the armistice Molly Hood arrived back in England bearing a fourth baby daughter, Diana, and soon afterwards took the family to live at her parents' home, Nettleham Hall. Dorothy had attended school in Worthing, but her mother decided that for the next year she would educate her daughters and some of their cousins herself, developing a curriculum that strongly featured her own interests in history, nature study, and poetry.
In 1920 the Crowfoots took a lease on the Old House in Geldeston, near Beccles. Here the four daughters spent the rest of their childhood, cared for largely by friends and relatives while their parents continued to spend most of the year in Khartoum, and subsequently Jerusalem. As the eldest daughter, Dorothy assumed a degree of responsibility for her sisters from an early age. She attended a small class in Geldeston run by the Parents' National Educational Union. Here for the first time she encountered chemistry, growing crystals of alum and copper sulphate. I was captured for life, she wrote in her memoirs, by chemistry and by crystals (Ferry, 8). She at once set up her own laboratory in one of the attics at home, and carried out experiments with materials bought from the local pharmacist. At the age of eleven she was enrolled in a mixed, state-run secondary school, the Sir John Leman School in Beccles. She successfully fought to be allowed to continue her studies in chemistry, then regarded as exclusively a subject for boys even though the chemistry teacher at the school, Criss Deeley, was a woman. When she was thirteen Dorothy and her sister Joan made a three-month visit to their parents in Khartoum, during which she received further encouragement from the government chemist, Dr A. F. Joseph. After helping her to identify a sample of ilmenite she had panned from a stream in the garden, he presented her with a surveyor's box containing forty-eight tubes of chemicals and tools for mineralogical analysis which she took home to add to her attic laboratory. Dorothy's mother also encouraged her interest in chemistry, presenting her with the published volumes of the Royal Institution Christmas lectures given by Sir William Bragg in 1923 and 1925. Here Dorothy read for the first time of the use of X-ray diffraction to see the arrangement of atoms in crystals, the technique demonstrated by Bragg and his son Lawrence in 1912.
After leaving school with an outstanding result in school certificate, she entered Somerville College, Oxford, in 1928 to read chemistry, with the intention of specializing in crystallography. There were only three other scientists among that year's intake at Somerville, and in the university's honour school of chemistry as a whole men outnumbered women by at least twelve to one. Dorothy quickly established a reputation as an exceptional student whose enthusiasm for laboratory work extended to analysing samples of ancient coloured glass sent by her parents from excavations in Palestine. She also found time to develop her own interest in archaeology through completing a detailed illustration of a Byzantine mosaic for one of her father's publications, and joining in local digs at weekends. She was an active member of the Labour Club; her interest in left-wing politics was also sparked by her mother, who had encouraged her to stand as a Labour candidate in a mock election at school.
After the first three years of her course Dorothy undertook research for part two of the honours degree under the supervision of H. M. Tiny Powell, the university demonstrator in the department of mineralogy. Powell had just acquired Oxford's first X-ray set for crystallographic work, which was installed in the University Museum. They worked on the structures of a class of organometallic compounds, the thallium dimethyl halides. Dorothy grew the crystals and took the X-ray photographs, calculating from the diffraction patterns she obtained that the compounds had a face-centred lattice similar to that of common salt but more elongated. A short report of the work was published in Nature
in 1932 (H. M. Powell and D. Crowfoot, Layer-chain structures of thallium di-alkyl halides, Nature
, 130, pp. 1312).
On graduating from Oxford with first-class honours, Dorothy went to Cambridge as a research student in the laboratory of John Desmond Bernal. Bernal had trained with Sir William Bragg at the Royal Institution in London, and now headed the X-ray crystallography laboratory in the mineralogy department at Cambridge. There he was pioneering the use of the technique to study biological molecules. Before Dorothy's arrival he had resolved a dispute between two rival groups of organic chemists over the three-dimensional structure of the sterols. As a result his laboratory was in great demand to analyse crystals of compounds whose structure was unknown. As Bernal was frequently abroad pursuing his political interests (he was a fervent admirer of the Soviet Union, and a prolific writer on the social function of science), much of this work fell to Dorothy. Most significantly, she assisted Bernal in the first description of a diffraction pattern taken from a protein, the digestive enzyme pepsin. Neither the data collection apparatus nor the methods available for mathematical analysis were sufficiently advanced at the time to solve the structure of this complex molecule, but the experiment established for the first time that proteins had regular structures and therefore were potentially amenable to crystallographic analysis (J. D. Bernal and D. Crowfoot, X-ray photographs of crystalline pepsin, Nature
, 133, 1934, 7945). Bernal also showed that in order to obtain good data from protein crystals it was necessary to keep them wet, photographing them inside a fine glass tube containing the mother liquor.
Soon after she left for Cambridge, Dorothy was offered a temporary fellowship at Somerville College. She hesitated, not wishing to leave the stimulating environment of Bernal's laboratory, but accepted when Somerville agreed that she could remain in Cambridge for the first year of the fellowship. She therefore returned to Oxford in 1934, completing her Cambridge PhD on the sterols two years later. With funds obtained from ICI on her behalf by Sir Robert Robinson, the professor of organic chemistry, she set up her own X-ray equipment in a new laboratory she shared with Powell in a basement corner of the University Museum. Almost at once Robinson presented her with crystals of another protein, insulin. Her successful attempt to obtain an X-ray diffraction pattern from the crystal (despite having dried it) was published in Nature
the following year, the first paper on which she was sole author (D. Crowfoot, X-ray single crystal photographs of insulin, Nature
, 135, 1935, 5912). She remained in close touch with Bernal, whom she regarded as a mentor on both scientific and political matters until the end of his life, but at the same time was recognized as a member in her own right of the élite circle of protein crystallographers then being established in Britain.
Marriage and family
In 1937 Sir William Bragg invited Dorothy to use the superior X-ray equipment at the Royal Institution to try to get better photographs of her insulin crystals. While in London she stayed with Margery Fry, the former principal of Somerville, who had befriended Dorothy when she was a student there. Staying in the house at the same time was , son of Robert Howard Hodgkin, provost of Queen's College, Oxford. He was Fry's cousin, a graduate in history who had been Dorothy's exact contemporary at Oxford. He had recently lost his job as personal secretary to the British high commissioner in Palestine through his vociferous support of the Arabs, had become a communist, and was now reluctantly being trained as a schoolteacher.
Dorothy's beauty had an other-worldly quality, with her slight figure, wavy fair hair, startlingly blue eyes, and preference for handmade clothes that made few concessions to fashion. She appears not to have noticed men at all until she went as a research student to Cambridge, where relationships frequently developed among the men and women who were represented more or less equally in the crystallography and biochemistry laboratories. When she first met Thomas Hodgkin, Dorothy was in love with Bernal, who was not only married but involved in at least one other serious alliance. But after only one or two further meetings, she and Thomas agreed to marry. By the time of their wedding on 16 December 1937, Thomas had discovered a vocation in adult education and was teaching history to unemployed miners in Cumberland. Dorothy, with the support of both families, retained her fellowship at Somerville, which had by this time been made permanent, and continued her research. She published under the name Dorothy Crowfoot until 1949, when she bowed to social pressure and gave her name as Dorothy Crowfoot Hodgkin on the first major publication on the penicillin structure.
The couple's first child, Luke, was born in December 1938. Soon afterwards, following a breast infection, Dorothy suffered an attack of acute rheumatoid arthritis. She was treated both with gold injections and by spa baths at Buxton and made a good recovery. But her hands were left permanently distorted, and the arthritis recurred as she grew older, often causing her intense pain. She had two further children, Elizabeth in 1941 and Toby in 1946. The family set up home in a flat in Bradmore Road, north Oxford, that belonged to Dorothy's parents-in-law. For the first eight years of their marriage Thomas lived mostly in lodgings where he was teaching, first in Cumberland and later in Stoke-on-Trent, returning to Oxford only for weekends and holidays. The Hodgkins' almost daily correspondence during this period provides a very full record of their activities and concerns. Dorothy meanwhile employed nursemaids and cooks to enable her to keep working.
In 1945 Thomas at last settled in Oxford when he was appointed secretary to the university's delegacy for extramural studies. Three years later he was invited to visit the Gold Coast, Nigeria, and the Sudan to advise on the establishment of adult education programmes in countries working towards independence from British rule. Thereafter he devoted himself to chronicling the progress of African nationalism. He resigned his post at Oxford and throughout the 1950s made extensive trips to Africa. From 1957 the Hodgkin family shared a large house in the Woodstock Road with Dorothy's sister Joan, whose marriage had broken down, and her five children. A constant stream of visitorseminent scientists, African politicians, schoolfriendsmingled over convivial dinners: Thomas was a great bon viveur and liked to cook for whomever happened to be passing through when he was at home.
In 1961 Thomas was personally appointed by Kwame Nkrumah as director of the Institute for African Studies in Accra, Ghana. Thereafter Dorothy visited him in Ghana for a month or two each year, until with Nkrumah's fall from power in 1966 Thomas returned to England. With his health in a precarious statehe was a lifelong smoker and suffered from emphysemahe and Dorothy eventually moved into Crab Mill, the rambling stone house in Ilmington, Warwickshire, that had been bought by Thomas's parents before the Second World War. They both received frequent invitations to visit other countries and often travelled togetheras far afield as Vietnam, India, Africa, and the US.
Thomas died in March 1982 in Tolon, Greece, while returning with Dorothy from a winter sojourn in the Sudan. He was buried in a nearby graveyard overlooking the sea. Dorothy was grief-stricken at his death. With his frequent absences (and several acknowledged infidelities), he could not be classed as a wholly supportive husband to a woman with a busy research career; however, at the time of their marriage he was unusual in accepting that his wife might have a career at all. And there seems little doubt that despite the outwardly unconventional course of their marriage, Dorothy and Thomas were bound by a strong mutual affection, admiration for each other's work, and passionately held political views.
In 1940 Dorothy received a large grant from the Rockefeller Foundation to continue her work on the structure of insulin. At the same time she took over equipment evacuated from Bernal's lab (he had moved from Cambridge to Birkbeck College in London), and two of his research assistants, Harry Carlisle and Käthe Schiff. With Carlisle she solved the complete three-dimensional structure of cholesterol iodide, including all the bond lengths and angles. This was the first crystallographic study she had pursued to its conclusion, and the first anywhere of such a complex organic molecule (C. H. Carlisle and D. Crowfoot, The crystal structure of cholesterol iodide, PRS
, 184A, 1945, 6483).
At the same time Dorothy was beginning to collaborate with other Oxford scientists on the study of penicillin. Howard Florey and Ernst Chain demonstrated its efficacy against bacterial infections in animals and humans during 1940 and 1941, but its chemical formula was unknown. The chemists suggested two opposing theories, the thiazolidine-oxazolone formula championed by Sir Robert Robinson, and the beta-lactam formula, which included an unusual four-membered ring, favoured by Edward Abraham and Ernst Chain. A successful X-ray crystallographic study could resolve the question, but penicillin proved extremely difficult to crystallize. Dorothy did not obtain suitable crystals until 1944, when samples of benzylpenicillin were shipped from America and brought to her by Kathleen Lonsdale, then a senior crystallographic researcher at the Royal Institution. With her assistant Barbara Low, one of her students from Somerville, Dorothy embarked on studies of three different salts of benzylpenicillin, each with a different heavy atom, trusting that the structure would emerge from comparisons between the three.
In collaboration with Charles Bunn and Anne Turner-Jones at ICI's Northwich laboratories, who analysed the sodium salt using the fly's eye method of modelling diffraction patterns, they solved the penicillin structure by 1945. With the help of the scientific computing service run by L. J. Comrie, they calculated the complete three-dimensional structure on a Hollerith punched card calculator, one of the earliest examples of crystallographic computing. News of the success gradually leaked out into the crystallographic community: what had begun as wartime secrecy continued after VE-day as commercial secrecy to protect the interests of the US firms who had undertaken the mass production of the drug, and the penicillin structure was not formally published until 1949 (D. Crowfoot, B. W. Rogers-Low, and A. Turner-Jones, The X-ray crystallographic investigation of the structure of penicillin, The Chemistry of Penicillin
, ed. H. T. Clarke, J. R. Johnson, and R. Robinson, 1949, 31067).
Oxford University was slow to recognize Dorothy's scientific distinction. She was shortlisted for the readership in chemical crystallography in 1944, but the post went to Powell, her former supervisor. In 1946 she was appointed to the lesser post of university demonstrator, which nevertheless doubled her income; she had previously kept her family on only her college fellowship. The following year she was elected a fellow of the Royal Society at the relatively early age of thirty-six.
Through her work on penicillin Dorothy had made many industrial contacts, and in 1948 Lester Smith of Glaxo gave her some dark red crystals of the anti-pernicious anaemia factor, vitamin B12. Soon afterwards the Glaxo chemists told her that the factor contained cobalt, which was heavy enough to show up on the Patterson maps that were Dorothy's preferred approach to structure analysis and could therefore help to solve the problem of phase determination. With a series of assistants, principally her student Jenny Pickworth (later Jenny Glusker), she embarked on a solution of the structure. At the same time Alexander Todd and his colleagues in Cambridge were working on a chemical analysis of the vitamin, whose formula was unknown. From Todd's laboratory Dorothy obtained a crystal of a cobalt-containing fragment of B12, the hexacarboxylic acid, that made it possible to elucidate the inner core of this complex molecule.
While actively encouraging the establishment of the first computing facilities in Oxford, Dorothy took advantage of an offer from Kenneth Trueblood of the University of California at Los Angeles to calculate atomic positions on one of the first electronic computers, the National Bureau of Standards western automatic computer, at no cost. Between 1953 and 1955 data and results went back and forth across the Atlantic, until the structure of the fragment was solved (D. C. Hodgkin and others, The crystal structure of the hexacarboxylic acid derived from B12 and the molecular structure of the vitamin, Nature
, 176, 1955, 3258). It proved to include an unusual set of rings known as the corrin nucleus. Working out from this nucleus, Dorothy and her colleagues solved the full structure of vitamin B12 by 1957. The fact that she had succeeded with a molecule of 100 atoms of unknown chemical formula moved Lawrence Bragg to describe her achievement as breaking the sound barrier.
As Dorothy established her pre-eminence in the field, honours quickly followed. Oxford University promoted Dorothy to a readership in 1955. In 1956 the Royal Society awarded her its royal medal, and four years later appointed her its first Wolfson research professor, a post she could hold at any university and which came with funds both for her personal salary and for research assistance and expenses.
In 1964 (having been proposed at least twice previously) she was awarded the Nobel prize for chemistry, only the third woman to be so distinguished after Marie Curie and her daughter Irène Joliot-Curie, and the fifth woman to win any science Nobel. To date (2001) she remains the only British woman scientist to win a Nobel prize. When the prize was announced she was visiting Thomas in Ghana, and she heard the news from two young Ghanaian reporters who had been sent to cover the story. The telegram from Stockholm arrived three months later, forwarded by sea mail from Woodstock Road by a niece brought up to be careful with money, along with all the other telegrams of congratulation.
In the following year Dorothy received a black-bordered envelope from Buckingham Palace, containing an invitation to join the Order of Merit. She and Benjamin Britten were admitted to the order to fill the vacancies left by the deaths of Sir Winston Churchill and T. S. Eliot. Although she disliked titles and had frequently declared to Thomas that she would refuse a DBE if it were offered, she saw the OM as rather different really (Ferry, 294), and acceptedjust as she accepted the first freedom of Beccles, an honour hastily invented for her by the town in which she spent her schooldays.
Dorothy's greatest scientific achievement was still to come. She had never given up hope of solving a protein structure, and specifically the structure of insulin which she had photographed in 1935. From the end of the 1950s onwards insulin was the primary focus of the research in her group. In 1958 and 1959 John Kendrew and Max Perutz at the Medical Research Council's Laboratory of Molecular Biology in Cambridge had solved the structures of myoglobin and haemoglobin, showing for the first time that protein molecules were indeed amenable to crystallographic analysis. They used the heavy atom method, in which the diffraction patterns of derivatives containing different heavy atoms at the same sites were compared. Insulin was more difficult because its threefold symmetry complicated the ever-present problem of calculating the phases. It also proved difficult to prepare suitable heavy atom derivativeseither the crystal would not take up the heavy atoms at all, or they might attach themselves to so many sites that it was impossible to compare one derivative with another, or the crystal might simply fall apart.
Dorothy acted as a source of inspiration and encouragement to an evolving population of researchers working on insulin in her lab, principal among whom was Guy Dodson who joined her in 1962 having just gained his PhD in New Zealand. Dodson soon afterwards married Eleanor Coller, an Australian with a degree in mathematics whom Dorothy had recruited as a technician. Eleanor Dodson undertook the task of analysing the vast amount of data generated by the insulin project with the limited computing resources available at the time, and subsequently played an important role in developing new mathematical approaches to solving the structure. Over the course of a decade a series of advances steadily improved both the quality of the data and the resources that could be deployed to analyse it. First, Dorothy learned from two Swedish chemists that it was possible to remove the zinc atoms that sat at the centre of each insulin molecule, and replace them with other metal atoms. Using this method members of the group successfully made lead and cadmium insulin crystals as well as zinc-free crystals. With the uranyl derivatives produced by Tom Blundell, who joined the department of chemical crystallography in 1964 as a part two student and stayed on to work with Dorothy's group, they at last had a series of suitable crystals that could in principle yield adequate data for a solution. But the data collection called for great accuracy and precision, comparing minute differences in the intensity of the X-ray reflections. Only in 1968, when Dorothy purchased an early model of the automatic four-circle diffractometer developed by David Phillips and Uli Arndt, did they finally obtain data of high enough quality.
Late in July of the following year it finally became clear that the electron density maps based on analysis of these measurements could be interpreted to show the positions of the atoms in the molecule. Over a single weekend, working almost non-stop, Dorothy, with Guy Dodson and M. Vijayan, a visiting scientist from Bangalore, built the first model of the molecule, an occasion which Dodson remembers vividly. It was a triumphant occasion in which Dorothy, though suffering from swelling ankles and forced into wearing slippers, worked with concentration and wonderful spirits (Dodson). In a characteristic gesture she gave the honour of presenting the structure a few weeks later at the 1969 meeting of the International Union of Crystallography to Tom Blundell, the youngest member of the group, who had been abroad and so missed the excitement of the model-building weekend (M. J. Adams and others, Structure of rhombohedral 2-zinc insulin crystals, Nature
, 224, 1969, 4915).
In the case of each of the three projects for which she is best knownpenicillin, vitamin B12, and insulinDorothy pushed the boundaries of what was possible with the techniques available. Her distinction lay not in developing new approaches, but in a remarkable ability to envisage possibilities in three-dimensional structures, grounded in a profound understanding of the underlying chemistry. She kept an open mind, not committing herself to a structure until it was supported by the unequivocal evidence of a successfully completed crystallographic study. She was exceptionally determined, persisting with apparently unpromising projects long after others would have given up in despair. While she did not consider it part of her role to explore the function of the molecules she studied, her results made it possible for others to increase their understanding of their biosynthesis and chemical interactions, and hence to develop improved therapies for disease. In 1976 her work was recognized by the Royal Society's most prestigious award, the Copley medal; she was the first woman to receive it.
Despite her increasing eminence, Dorothy retained a gentleness of manner, quietness of speech, and egalitarian outlook that inspired loyalty and devotion among most of her younger colleagues. She drew her research team partly from among the Somerville chemistry students she supervised (these briefly included Margaret Roberts, later the British prime minister Margaret Thatcher), and partly from a steady stream of mostly international post-doctoral workers who wrote asking if they could join. She insisted that everyone in her lab, from the most junior technician to the most distinguished academic visitor, simply call her Dorothy.
Partly, though not entirely, as a result of the Somerville connection the lab contained approximately equal numbers of male and female research workers, exceptional among chemistry laboratories at Oxford. Dorothy herself denied that her gender had ever hindered her progress, but when she encountered instances of discrimination against her own junior female colleagues she resisted them vigorously. For example, she was incensed to discover that female graduate students routinely had their grants reduced on marriage. However, it took a stint on a committee investigating the administration of Birmingham University in 1970 to bring home to her the insecurity of many women workers with families, including those in her own lab. After this she ensured that they had proper contracts with paid maternity leave, rather than simply paying them for the hours they worked.
She directed the laboratory with a very light touch, taking it as read that everyone was as committed as she was to the task in hand. To outside observers the lab could appear chaotic, with the younger members as likely to be engaged in games of indoor cricket or political arguments as scientific experiments. Dorothy herself avoided administrative tasks as far as possible, unless they were directly related to advancing her research. The officers of funding bodies (particularly the Rockefeller Foundation, which continued to support her until the 1960s) often had to remind her to ask for grants. Yet against all appearances the lab was immensely productive.
For all its success, her group was entirely dependent on Dorothy for its continued existence; not one of her assistants held a permanent post. As an interdisciplinary science, the crystallography of biological molecules did not fit into any of the established departments at Oxford. Over the years it was moved from mineralogy to inorganic chemistry, thence to zoology, and ultimately (well after Dorothy's retirement) to biochemistry. It was always a challenge to find enough space to accommodate her research assistants and the equipment that she had no difficulty in funding through outside grants: her appointment to the Wolfson chair was greeted privately by the university authorities as a new and confusing problem (Ferry, 284). But although at different times Dorothy received offers to move elsewhere that included attractive research facilities, she chose to stay in Oxford because of her family circumstances.
With a view to strengthening the position of crystallography in Oxford, and recruiting someone to deputize for her during her increasingly frequent absences abroad, in the early 1960s Dorothy encouraged David Phillips, then at the Royal Institution, to think of moving to Oxford. He eventually did so in 1966, having negotiated with the university authorities a personal chair, permanent posts for several members of his group, and space for a laboratory of molecular biophysics within the new department of zoology. But Dorothy's own group remained separate from Phillips's, belatedly accommodated in the adjacent department of experimental psychology, and by the time she retired all of its members had found jobs elsewhere. As long as she had been present in Oxford, Dorothy had been able to keep her show on the road by virtue of her great distinction and her powers of persuasion. But she had never undertaken the political negotiations that would have been necessary to establish her group on a more permanent footing.
International and political activities
In 1925 Dorothy's mother, who had lost all four of her brothers as a result of the First World War, took her to observe the sixth assembly of the League of Nations in Geneva. Dorothy retained a lifelong conviction that the problems of the world could be resolved through dialogue, and that armed conflict should be avoided at all costs. Under the influence first of her mother, and later of Bernal and Thomas Hodgkin, she also developed an unshakeable faith in socialism and an admiration for communist regimes that often blinded her to the abuses of human rights perpetrated by their leaders.
However, she was no party hack: she exercised her political consciousness on the level of personal contacts with individuals, being particularly concerned to keep channels of scientific communication open despite antagonism between East and West. As a result her politics never prevented her from interacting comfortably with those who held more conventional views, whether in the scientific or the political sphere. The only serious opposition she encountered was from the US government during the McCarthy era. Her membership of an organization called Science for Peace (and possibly her links with Bernal and Thomas Hodgkin) resulted in her being declared statutorily inadmissible by the state department in 1953, and she was unable to obtain a waiver of this ruling until 1957, despite numerous appeals on her behalf by members of the American crystallographic community. For the rest of her life every visit to the US necessitated a trip to the embassy in London to have the waiver renewed. Her exclusion from that country in 1953 provided an opportunity for her to make the first of many visits to the Soviet Union. Her support for its scientists and for EastWest détente
was recognized by the Mikhail Lomonosov gold medal in 1982, and by the Lenin peace prize in 1987.
In 1959 Dorothy was one of a delegation of British academics who visited China to mark the tenth anniversary of the founding of the People's Republic of China. On discovering that Chinese scientists were working on insulin, she gave them every support and encouragement, and made several return visits right through the period of the cultural revolution, when China was virtually closed to the outside world. In her capacity as president of the International Union of Crystallography from 1972 to 1975 she was the first to report the success of the Chinese team in arriving at an independent solution of the insulin structure, and she worked tirelessly for the readmission of China to that body (finally achieved in 1978). She developed equally warm relationships with India through a succession of visitors to her lab, who came mostly from the Indian Institute of Sciences in Bangalore during the 1960s and 1970s.
In addition to promoting international scientific contacts, she realized that her Nobel prize put her in a position to campaign on behalf of other causes in which she believed strongly. She was a member of the Campaign for Nuclear Disarmament, and vehemently opposed America's intervention in Vietnam and Cambodia. She accepted an invitation to become president of the Medical Aid Committee for Vietnam, and later sat on an international commission into US war crimes in Vietnam. She and Thomas visited North Vietnam in 1971, and again in 1974 when their daughter Elizabeth was teaching English and editing English-language publications in Hanoi.
In the early 1960s Dorothy had attended a meeting in London of the Pugwash Conferences on Science and World Affairs, an organization founded by Bertrand Russell, Albert Einstein, and others in 1955 to bring together scientists from East and West to discuss disarmament. She attended a few further meetings, but did not become actively involved until 1975, when she was invited to become its president. Accepting with some misgivings at the commitment involved, she thereafter travelled tirelessly on behalf of the organization, working in particular on a goal dear to her heart, the participation of Chinese representatives in the Pugwash meetings. After her former student Margaret Thatcher was elected prime minister in 1979, she took the opportunity to approach her personally to argue for a rapprochement with the Soviet Union, and corresponded with her on detailed questions such as the verification of chemical test bans.
Another cause in which she believed strongly was that of support for higher education. In 1970 she was elected chancellor of the University of Bristol, normally a purely honorary position. However, she made a point of visiting the students and hearing their concerns, and used the role to protest about the swingeing cuts in university budgets introduced by the government in 1981, which resulted in reduced student numbers and the closure of Bristol's school of architecture. She also helped to establish Hodgkin House, a hostel for international students at Bristol, in memory of Thomas, and encouraged the students to raise funds to support a Hodgkin scholarship for students from South Africa.
Dorothy retired from her university post in 1977, but retained a room in the chemical crystallography department where she could work. She continued to refine the structure of insulin with Guy Dodson, who had moved to the University of York, until 1988. In that year they published a solution of the structure at such high resolution that the position of every intervening water molecule could be discerned (E. N. Baker and others, The structure of 2Zn pig insulin crystals at 1.5Å resolution, PTRS
, 319A, 1988, 369456).
In the same year Dorothy gave up her other commitments, to Pugwash, the University of Bristol and other organizations, and began to turn down more of the invitations to travel and speak that she still received in great numbers. Her arthritis was making walking increasingly difficult, and she had begun to use a wheelchair. In 1990, a few months after friends and colleagues from all over the world had gathered in Oxford and at Crab Mill to celebrate her eightieth birthday, she fell at home and broke her hip. Despite her great frailty she recovered, although she never walked again and she ceased to give lectures. However, she continued to delight in the company of her children, grandchildren, and great-grandchildren, and of former colleagues who visited whenever they could. She retained an intense interest in world affairs and scientific progress.
In September 1993 the International Congress of Crystallography was to be held in Beijing. After watching a television programme critical of China, Dorothy suddenly announced that she intended to go to the congress, and no one could dissuade her. Both the Royal Society, which was to fund her trip, and her Chinese hosts expressed their anxiety that she would not survive the journey. Her doctor refused to certify her fit to travel. But accompanied by Elizabeth and with the support of the Dodsons she successfully made the journey to Beijing and back. While there she attended several of the lectures, and back in her room each evening she would whisper shrewd observations about them (Ferry, 401). But her obvious frailty was a shock to many of her international colleagues who had known her previously.
In the following July Dorothy suffered another fall, and two weeks later, on 29 July 1994, she died at home at Crab Mill with her family and friends around her. She was buried in the churchyard of the parish church of St Mary the Virgin in Ilmington. A service was held in her memory on 4 March 1995 at the university church of St Mary the Virgin in Oxford, attended by all of her family, many of her scientific colleagues, and a large crowd of well-wishers including Sir Isaiah Berlin, Baroness Thatcher, and Lord Jenkins. The address was read by Max Perutz, who had been a close friend since he came to Cambridge from Vienna as a young researcher in 1936. His summing up of Dorothy's character has not been bettered:
There was a magic about her person. She had no enemies, not even among those whose scientific theories she demolished or whose political views she opposed … It was marvellous to have her drop in on you in the lab, like the Spring. Dorothy will be remembered as a great chemist, a saintly, tolerant and gentle lover of people and a devoted protagonist of peace. (Ferry, 402)
Many of the bodies with which Dorothy was associated took steps to ensure that she would remain permanently in the public eye. The Royal Society commissioned portraits from Graham Sutherland and Bryan Organ, together with an exquisite pen-and-ink drawing of her hands by Henry Moore. Somerville College has a bronze bust of Dorothy modelled from life by Anthony Stones in 1983. The best-known and most controversial portrait is the 1985 painting by Maggi Hambling that hangs in the National Portrait Gallery. It shows Dorothy in severe, black-framed spectacles, wisps of hair rising unrestrained from her head, hard at work in her room at Crab Mill. To indicate the rapidity with which Dorothy worked through the electron density maps on her cluttered desk, the artist has given her an extra pair of hands. Dorothy is also commemorated through the Dorothy Hodgkin fellowships awarded by the Royal Society to young researchers, many of them women, and by a plaque placed on the wall of the inorganic chemistry laboratory at Oxford University as part of the Royal Society of Chemistry's national chemical landmarks scheme.