by Andrew Brown
Stradling arranged to meet Bernal in London, and at the appointed time found Sage already in his office reading Stradling’s official papers.56 This minor breach of protocol did not stop Sage being appointed to the Civil Defence Research Committee, along with a small number of engineering professors and physical scientists, to advise the Lord Privy Seal and ‘to secure the fullest possible co-ordination over the wide field of work now comprised in civil defence’.57 Even after Bernal’s name was officially put forward there were concerns about his fitness to serve. A senior Home Office civil servant, while endorsing the rest of the committee, wrote that he was ‘not quite sure about Professor Bernal. Last year he was less reliable owing to his rather extreme political affiliations. But, this apart, he would be a reasonable addition.’58 Anderson replied with a pencil-written note on the Home Office minute: ‘Get on with it quickly. I don’t think in present circs. we need object to Prof Bernal.’
Sage attended the first meeting in London on 12th May and like other members of the committee signed the Official Secrets Act, apparently with no qualms. He was immediately appointed to Sub-Committee A, which was constituted ‘to study the physics of explosion, blast and penetration’.59 Amongst the most urgent problems identified by Stradling for the Sub-Committee to consider were blast measurements, the design specifications of air-raid shelters and the question of whether the tube tunnels passing under the Thames needed to be reinforced against possible bomb damage.
The British Government managed to preserve the traditional freedoms of scientific research to a remarkable degree in World War II and were rewarded for their trust with a string of ingenious inventions and discoveries that not only changed the course of the war, but still have a beneficial impact on our lives. Bernal in ‘Science and National Service’ emphasized that both citizens and scientists needed to keep in mind the ultimate aim of science, which, in his opinion, was to improve human welfare in times of peace. While it would be fatuous to suggest that events turned out to some extent as he hoped because of what he wrote in that 1938 editorial, he undoubtedly raised the scientists’ own awareness of their roles in society and added to their collective confidence to challenge authority, when it seemed necessary.
Bernal’s opposition to fascism in the thirties was public, relentless and right. Yet he completely ignored the growing evidence of even worse atrocities from the Soviet Union. He was far from alone in this, and the Spanish Civil War with the open involvement of Hitler’s and Mussolini’s forces, gave Stalin the most effective cover for his unspeakable terror. The twin evils were conjoined in the Nazi–Soviet Pact of August 1939, which came as no surprise to Polanyi and Muggeridge, but which so contorted the collective thoughts of progressive British intellectuals that, almost to a man and woman, they ignored it at the time and then forgot about it altogether.
One event widely covered in the British press that must have caught Bernal’s attention was the great Moscow show trial of 1938, in which Bukharin was one of the famous defendants. In addition to the blanket accusations of espionage, wrecking, undermining Soviet military power and supporting overthrow of the socialist system to return to capitalism, Bukharin faced the extra charge of plotting to seize power after the 1917 Revolution through the assassinations of Lenin and Stalin.60 Here was a man that Bernal admired, had talked to at length about science, socialism and the future, facing an appalling fate. After being tortured, and to prevent the execution of his young wife, Bukharin made a partial confession and was shot. Although Bernal could not have been expected to imagine the grotesque cruelty of Bukharin’s tormentors, did he just accept the confession at face value? Or did he make the sad reconciliation that innocent blood must be spilled to achieve the ultimate goals? Margaret Gardiner does not believe that Bernal subscribed to the ruthless principle of the end justifying the means, but rather that his political stance was grounded in emotion and this allowed psychological defences that resulted in him making excuses for or denying unpleasant facts. Margaret thought that he did have doubts about communism, but never mentioned them to her. She said to him at one point, ‘I suppose if you were ordered to kill me, you would.’ To which Bernal replied, ‘Yes I would – but very reluctantly.’61
8
The Entertainment of the Scientist
Dorothy Crowfoot spent the summer of 1934 in Cambridge taking more X-ray photographs of pepsin, but then returned to Oxford to take up a fellowship at Somerville College.1 At the same time, Bernal lost his other PhD researcher, Helen Megaw, who went to Vienna to spend a year working as a post-doctoral student with Hermann Mark, now professor of physical chemistry there. The loss of these two hard-working and talented young women resulted in a temporary drying-up of the stream of new data from Bernal’s laboratory. His growing involvement with the Association of Scientific Workers, FIL and the Cambridge Scientists Anti-War Group precluded him from spending the long hours necessary to generate and interpret X-ray photographs, and he could no longer summon the solitariness of purpose necessary to undertake such demanding work himself. He spent almost as much time in London as he did in Cambridge and was often out of the country. At the end of 1934, he spent two months in the USSR with Margaret Gardiner, coming home via Vienna. At the beginning of 1935, he returned to Paris and stayed with his cousin, Persis: his attempt to rekindle their affair was rebuffed so that the week was ‘rather miserable though wonderful food’.2 When he was in Cambridge, he continued to live with Eileen and their two sons, and although he was quite open about his divided affections, he experienced some ‘difficulties with Margaret in London’.3
Soon after the week in Paris, Bernal became ill with a fever and jaundice. Word of his illness reached Dorothy Crowfoot in Oxford just as she had made the first X-ray photograph of a crystal of insulin. She was bursting to tell Sage the news, but hesitated and instead wrote to Eileen asking her to tell him about the unit cell measurements of the rhombohedral-shaped crystals, ‘if he is well enough’.4 He was not all well, but nothing could stop him from responding to this exciting breakthrough. He made cryptic suggestions to Dorothy about how she might proceed and also urged her to write up her preliminary results. So she wrote a letter to Nature, but having posted it, started to get cold feet. This was her first independent research and she had grown the crystals herself, adding a dash of zinc to the insulin in solution so that the metal would be incorporated into the crystal. Unlike the pepsin crystals she had worked on in Sage’s laboratory, the insulin crystals did not disintegrate on drying so that she mounted them in the dry state for the ten-hour X-ray exposure. Her main concern was that the crystallization process and then the long period of radiation might have altered the chemical structure in some way, so that the diffraction pattern she obtained was not truly that of active insulin. She confided as much to Sage in a letter, dated 7th March: ‘I’m rather worried about the “insulin”… I wish really I’d waited the Nature letter till the biological tests were made. It’ll serve me absolutely right if the thing is all wrong.’5 To set her mind at rest, Bernal arranged for some of the zinc insulin crystals to be sent to Sir Henry Dale, the leading physiologist, for assay. Dale wrote to Dorothy, on 19th March, assuring her that the crystalline zinc insulin that she had been using for spectroscopy retained its biological activity and therefore the radiation exposure ‘did not significantly change the structure of the crystalline compound’.6
At Oxford, Dorothy continued to study the structure of sterols, a subject to which she had been introduced by Sage soon after she arrived in his laboratory, and which now formed the basis of her PhD thesis. She once described the hectic pace of working with Bernal in a Christmas letter to her parents. She had brought fresh photographs of ergosterol to Bernal in London, which he analysed on his way to give a paper at the Chemical Society: ‘It was simply marvellous. Sage was working out structures all the way there – in the bus, in the tube and in the station waiting for the next train – to say nothing of during the meeting while everyone else was speaking. And then it all came o
ut beautifully arranged and ordered as though he had known it all weeks ago!’7 Sterol structures remained the subject of controversy between British and German chemists, and Sage continued to supply expert opinion to both camps. In June 1935, Windaus wrote to him from Göttingen with a surprising new structure for calciferol (vitamin D). Bernal studied it for some months and concluded that for both Windaus’ formula and his own crystallographic data to be correct, the molecule would have to be curled up in an improbable way. He wrote back to Windaus in September admitting that he was still uncertain about the formula and found ‘it almost equally difficult to agree with your formula’8 or an alternative proposed by Rosenheim at the National Medical Laboratory in London. Bernal asked Windaus to send more crystals of different vitamin D compounds, no doubt intending to send them to Oxford for Dorothy to photograph.
Now that she was working in her own laboratory, Dorothy, in addition to generating new data on insulin, subjected some of her previous photographs of sterols to more rigorous analysis than the rather impressionistic review they had received from Bernal. She made use of a new mathematical tool developed by Lindo Patterson, who had worked at the Royal Institution with Astbury and Bernal. The Patterson map, derived from a Fourier analysis of X-ray diffraction waves (a technique that breaks complex waveforms down into constituent sine waves), is like a contour map; it can be used to define the distances between atoms in a crystal lattice. The calculations had to be made by hand and were laborious, often involving hundreds of trigonometric functions for each spot on the X-ray photograph. Dorothy, from the first, was a gifted exponent of the Patterson, and wrote to Bernal in June 1936 about her ‘first attempt at a Fourier of cholesteryl bromide’ – given the residual phase uncertainties with such a complex molecule and the limitations of the Patterson technique, she was pleased that ‘the whole thing does look rather surprisingly like a sterol.’9
Dorothy was in her mid-twenties, nine years younger than Sage, her PhD supervisor and scientific mentor. She had fair hair which, ‘when caught by the sun, stood around her head like the halo of a stained-glass window mediaeval saint’10 and she possessed a slow, captivating, smile, which only added to her air of innocence. Sage, despite his worldly experience, retained a youthful appearance with dimples and his trademark shock of thick, fair hair. In addition to introducing her to many of the leading biochemists and crystallographers in Britain and Europe, Bernal, through his example and conversations, persuaded Dorothy to take an interest in some of the political activities that consumed him. Although she knew about his ongoing affair with Margaret Gardiner and his marriage to Eileen, Dorothy was infatuated with Sage, and inevitably the two became lovers. There was not much opportunity for them to spend time together, but in November 1936 they travelled to the Netherlands, where Bernal had been invited to lecture on sterols to the Dutch Biochemical Society and to visit some university departments. Sage made a bargain with Dorothy that ‘he would give all the lectures and that I should write up a lecture text, which should be published… every morning in Holland we hurried down to breakfast to get the first news on the radio, of whether Madrid had fallen or not. All that time it held out.’11
On their return from Holland, as one of her PhD examiners, Bernal had to write a report on her 300-page thesis, ‘X-ray crystallography and the chemistry of sterols’. It was a monumental piece of work, which he described as ‘the first comprehensive attempt at a joint crystallographic and chemical study of a group of substances of great intrinsic interest as well as of critical biological importance.’12 Bernal was careful to emphasize the impossibility of arriving at complete solutions for sterol structures because of their complexity and the absence of ‘centres or axes of symmetry in the molecules’ but was genuinely impressed by the style and depth of Dorothy’s research. For once, Sage was discreet about their short affair and several reasons can be advanced for his uncharacteristic reticence. First, Dorothy was his PhD student and while he did not want to provoke the attention of the University authorities by his open immorality, he wanted even less to be responsible for any stain on Dorothy’s academic reputation. Second, Margaret Gardiner was pregnant and already posing ‘complications’; indeed he was ‘converted to trial monogamy with one spectacular failure’.13
Margaret’s son, Martin Bernal, was born in March 1937. That same month Dorothy was introduced to Thomas Hodgkin, a scion of the Quaker family of distinguished intellectuals. He had recently joined the CPGB and was training, unhappily, to be a teacher. Hodgkin was Dorothy’s age, classically handsome, and entertaining – despite a current period of depression. That summer, Dorothy wrote to ‘Sage dear’ expressing happy memories of time they had spent together, but suggesting a disentanglement of their physical relationship: ‘Do you think it would be very stupid to stay with you only for walking and talking?’14 A less tentative letter followed a few weeks later with Dorothy telling Sage that she felt ‘perfectly happy and oddly virtuous’. She said that she expected to marry Thomas, but could not ‘bear to think of you miserable and want to keep you somehow deeply in my life’.15 Absurdly for such a practiced Lothario, Bernal did seem to mind when Dorothy became engaged to Thomas, but was soon mollified. He always tried to stay friends with his ex-lovers, and in Dorothy’s case the depth of their shared passion for crystallography made it inconceivable that they would not remain on the closest personal terms.
A replacement for Dorothy in Bernal’s laboratory appeared towards the end of 1935. He was Isidore Fankuchen, the atheist son of a Brooklyn rabbi. After graduating in physics from Cornell University and working in various departments in the USA, Fankuchen came to Manchester in 1934 to work with Lawrence Bragg. Bragg wrote to Bernal about him in October 1935, asking if Bernal would mind him taking up work on the sterols.16 The request was prompted by a chemistry professor in Manchester, Heilbron, who thought the sterol formula proposed by Rosenheim from the National Medical Laboratory was wrong. Bernal replied that he shared Heilbron’s concern and would welcome active cooperation with Fankuchen, who should visit Cambridge. The visit was soon arranged and ‘Fan’ never returned to Manchester. He was the perfect addition to Bernal’s meagre staff – technically accomplished, inquisitive, good-natured, politically radical and tactless. The research tradition in Bragg’s department was to study inorganic substances, especially metals and alloys, which was why Bragg felt obliged to write to Bernal rather than just let Fan trespass into the organic world of sterols. For a short period after arriving in Cambridge, Fan worked on the structure of uranium compounds, and although he remained at heart a physicist, he soon became involved in the study of proteins. The protein was in a new guise – a virus.
Tobacco mosaic virus (TMV) causes tobacco leaves to become variegated, dark and light green, and the plants to be stunted. It is the most stable of viruses and was the first to be discovered at the end of the nineteenth century, when it was shown that sap from an infected plant remained infectious after being passed through filters that retained all known bacteria. Other viruses were identified over the years, some of which cause serious diseases like polio and smallpox in humans, but detailed knowledge about their structure remained elusive. They were known to be extremely small; unlike bacteria they could not be cultured on inert media, but needed host cells in which to reproduce, and they could not be made visible under the light microscope by staining procedures. In 1935, Wendell Stanley working at the Rockefeller Institute succeeded in preparing TMV as a crystalline protein – the first virus to be isolated. He showed that all the virus activity present in infectious sap was retained in the crystalline material, and that one billionth of a gram of the material was enough to cause infection. Stanley’s research was the biggest breakthrough in virology in over thirty years, and was immediately taken up in Cambridge by the biochemist Bill Pirie and Fred Bawden, (a plant virologist who had recently taken a position at the Rothamsted Experimental Station in Hertfordshire). Pirie and Bawden had been studying viruses that attack potato plants, a more important crop in
England than tobacco. Now Bawden switched to growing tobacco plants infected with TMV, and ‘in a few weeks, using methods that had been standard in protein chemistry for 50 years’17 (clarifying the sap in a centrifuge), they succeeded in preparing gram quantities of liquid crystalline TMV material. Stanley had reported his crystalline material as pure protein, but Pirie and Bawden detected 0.5% phosphorus and 2.5% carbohydrate. They concluded that in addition to protein, there was ‘nucleic acid of the pentose type’18 (i.e. RNA) present.
It was natural that Pirie should bring some crystalline material to Sage for X-ray study. It was equally natural for him to give the task to his new assistant Fankuchen. Fan immediately rose to the challenge, impressing Bernal: ‘Fankuchen threw himself into this examination. He excelled in the devising of apparatus specially tailored for the purpose. One problem was that of examining the liquid crystals at very low angles, and for this monochromatic X-rays were essential. He devised an X-ray monochromator made of a pentaerythritol crystal sliced in such a way that it could give a very narrow beam of strictly monochromatic radiation [X-rays of a single wavelength] of high intensity.’19 Bernal and his group observed that TMV in aqueous solution forms two layers. The bottom layer is a gel in which all the rod-like particles are aligned. In the less-dense top layer, there is no orderly arrangement and the particles are pointing in all directions (isotropic). Bernal thought of them as tumbling in the solution, with each particle sweeping a sphere. As the concentration of the solution is carefully increased, there comes a point where those spheres touch, the particles are no longer free and instead form a liquid crystal phase. If, at that critical concentration, the solution is gently agitated, the long rod-like particles become linearly orientated and, when viewed in polarized light, give a beautiful shimmering effect, known as anisotropy of flow. The Cambridge scientists demonstrated this at a Royal Society soirée, where instead of using mechanical stirrers, they let a goldfish and seahorse swim through the dilute solution. According to Pirie, the demonstration was more popular with fish physiologists than with plant pathologists, and their discovery of the first nucleoprotein ‘excited no interest at all’.20
