84 pages • 2 hours read
James D. WatsonThe Double Helix
Nonfiction | Book | Adult | Published in 1968A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Chapters 17-20Chapter Summaries & Analyses
Chapter 17 Summary
Pauling’s visit to London is blocked by the American State Department due to suspicions about his politics beliefs and his public involvement with the World Peace movement. Watson is furious about the decision to let a world-leading scientist attend a non-political meeting, and of the conservative attitudes of the governing board at Cal Tech.
Luria is barred from attending the London meeting for the same reason, so Watson is left to give a survey of the latest phage developments, in his absence. The summary is provided in advance. The key point referenced is that the infection of bacteria by a phage involves the injection of viral DNA into the host, powerful new proof “that DNA is the primary genetic material” (86).
Watson finds little support for his ideas on TMV at the gathering. Conversations with Wilkins reveal that the models they sent haven’t been used, relations with Franklin have got worse, and that her data apparently now tells her firmly that DNA is not a helix: “[r]ather than build helical models at Maurice’s command she might twist the copper-wire models about his neck” (88).
Wilkins offers to return the models, and seems reassured that Watson is working on TMV.
Chapter 18 Summary
Working late one night in mid-June, Watson makes significant progress on TMV by taking the x-ray picture that proves its helical structure.
The next morning, he gets Crick to confirm his interpretation of the data. Watson thinks he’s made as much progress as he can on TMV now, and the two decide it’s time to renew their efforts on DNA.
Attention turns to the chemical base composition of DNA, and some experiments undertaken by Charles Chargaff. Chargaff’s DNA samples have shown a very similar number of adenine (A) and thymine (T) molecules, on the one hand, and guanine (G) and cytosine (C) molecules on the other. The relative proportions of G&C and A&T have varied from organism to organism.
Watson feels this was important, and Crick comes to agree, after conversations with a theoretical chemist, John Griffith, about gene reproduction during cell division.
One current theory was that a gene replicated by first forming a negative image of itself and using this negative image as a mould, to create the positive. But the crucial question was, how? What were the forces of attraction involved in this process. In conversation with Griffith, Crick starts to believe that “DNA replication involved specific attractive forces between the flat surfaces of the bases” (92). If the gene replication theory was correct, they might be able to calculate the bases.
Griffith comes back to say a semi-rigorous argument could be made that A and T would stick to each other by surface; Crick then recalls these were the pairs mentioned by Chargaff. They seem on to something, but the math was still imprecise, and Griffith was reluctant to commit himself.
Chargaff arrives on a visit to Cambridge and they meet during a formal dinner. He’s very dismissive of Watson and Crick, especially when Crick forgets parts of the formulas relating to his argument.
The next morning, Crick shows up to double-check something with Griffith. He finds him in his office with a girl. Watson reflects: “it was all too clear that the presence of popsies does not inevitably lead to a scientific future” (95).
Chapter 19 Summary
Watson goes to Paris for a major conference that brings a lot of the heavy hitters together. He spots Chargaff, who throws him “a sardonic smile” (96). Max Delbruck, from Washington, is there. Delbruck readily saw to the extension of Watson’s Cambridge fellowship, despite being unenthused by his work on helices and structural chemistry, or his “love affair” with Cambridge (96).
Pauling gives a talk which is packed with admirers, but it’s just going over published content: “no new fireworks went off” (97).
Wilkins is there, feeling morose and unimpressed by the bulk of what he hears. Watson invites him to a gathering of phage scientists but he takes ill that night.
The next day, Watson briefly gets to talk to Pauling and his wife, Ava Helen. Not much comes from the few words spoken with Pauling, but Watson hears from Helen that their son Peter will be at the Cavendish the following year, studying under Kendrew. He will be coming with his attractive sister, Linda, who is beloved by many students at Cal Tech. Watson offers to help Peter settle in, and reflects to himself that “Peter and Linda would undoubtedly liven up the Cambridge scene” (99).
The conference concludes with a garden party in an aristocratic house. Watson has to borrow appropriate clothes to fit in. Amidst fine food and art, he senses “the value of a cultivated aristocracy” (100), and is amused to find that the Baroness has been warned in advance about an eccentric under-dressed English man (himself) who she’s rather sad to discover hasn’t shown up.
Chapter 20 Summary
After the summer, Watson and Crick are both preoccupied with different projects. Watson returns to biology, and the sexual reproduction of bacteria. He picks up on new evidence that bacteria have distinct sexes, and is excited by the ideas of Bill Hayes, who has posited that only a fraction of the male chromosomal material is passed to the female cell. This runs against the thinking of the established expert, Joshua Lederberg. Hayes’ idea significantly simplifies things, and Watson is excited at the idea that he might beat Lederberg to the correct interpretation of some of his own data.
Crick has been thinking about DNA, and carried out some experimental work linked to Chargaff’s findings on base pairs. He goes to London to discuss this with Wilkins but the meeting comes to nothing.
They learn from Peter Pauling (now in Cambridge) that his father is not currently focusing on DNA, but on the super-coiling of the a-helix in keratin. This troubles Crick, who had a side project proposing something similar about “coiled coils.” The news makes him redouble his efforts, and he rushes off a paper on the matter.
There is growing acknowledgement that Crick is a real talent, with significant work to his name. He’s offered a fellowship in Brooklyn for the following year, which he tentatively accepts.
Watson stays focused on bacterial mating, but occasionally meets with Wilkins. He learns the relationship with Franklin is just as tense, though her x-ray pictures are “getting prettier and prettier” (106). She’s still not interested in helices, but she has a new idea that the sugar phosphate backbone is on the outside of the molecule. Without access to the data, it’s hard for Watson and Crick to judge.
Chapters 17-20 Analysis
These chapters see Watson make decisive progress on TMV and a return to DNA, but without as yet anything decisive. They advance some important scientific explanation concerning Chargaff’s findings about the base pairs A & T and C & G, which will be crucial to eventually solving the structure of DNA.
Despite the fact that Watson and Crick are growing in stature and accomplishment, each now with some decent work to their name, the way Chargaff responds to them is interesting. They are dismissed as nuts, eccentrics, young upstarts. This touches on the question of academic hierarchy. Science is in one sense a meritocracy, but there is also clearly a hierarchy of sorts based on age and perceived stature. Watson and Crick take delight in trying to prove themselves and score a victory against the old guard, be that in the form of the great science celebrity Pauling, or the biology expert, Joshua Lederberg. And they have the advantage of relative youth on their side, with all the zeal and imagination it brings.
We have the motif of the scientific race repeated again in both Watson’s work on the reproduction of bacteria and Crick’s work on the “coiled coil” (105). Watson’s interest in Hayes’ theory again echoes their approach to DNA, as what appeals to him is the principle, and liberating power, of simplicity in nature: the possibility that crucial processes can be clearly understood, in contrast to Lederberg’s “rabbinical complexity” (102).
In Chapter 17, we have the interesting aside that Pauling and Luria were prevented from attending a meeting in London by the US government on the grounds of their political affiliations. This was in the McCarthy era, when there was heightened concern in the US about the infiltration of communist ideas, especially in intellectual and educational circles. It led to political repression and a kind of cultural paranoia, illustrated here. Pauling had been a sponsor of world peace events that were interpreted by some politicians as a form of communist sympathising.
It becomes clear that Watson’s own politics are broadly progressive and left leaning, and he is critical of the conservatives on the governing board of Cal Tech, who he imagines want rid of Pauling. Watson and Pauling may be scientific rivals, but they are political allies. There are hints here and elsewhere of the broader counterculture that was emerging in the post-war era, of which intellectuals and universities were a key part.
Previously, we mentioned that science and young women are presented by Watson as two shared but separate fields of interest. The anecdote at the end of Chapter 18, where Crick finds Griffith in his lab with a young woman, reaffirms this division, in the very moment that its golden rule is broken. Watson comically observes, “it was all too clear that the presence of popsies does not inevitably lead to a scientific future” (95).
An interesting development of the theme comes in Chapter 20, when Watson writes jokingly “I was pre-occupied with sex” (101) with the obvious double meaning between sex (ordinarily understood) and his scientific interest in the reproduction (“sex-life”) of bacteria. At the end of the chapter he replays the same pun: “I returned to my thoughts about sex” (106), comically blurring the domains of sex and science. In contrast to the end of Chapter 18, here thinking about sex is scientifically productive.
Intriguingly, Watson, for all his frankness, never directly mentions any of his own romantic or sexual experiences. He has much more to say about the reproduction of bacteria. But his pun about being pre-occupied with sex also makes for an interesting point. It underlines the fact that the scientist is not removed from the nature of things she or he is analysing. They are not objective and removed spectators of nature, but living, feeling, desiring organisms. The drive to reproduce, the power of sexuality, is there, operating for them on a human level, just as it does on the molecular level they are exploring and attempting to map.
While little tangible progress is made directly on DNA in these chapters, certain pieces are clearly being lined up. There is Watson’s work on TMV, with its rationale for a helical structure, and, crucially, the focus on the nucleotide base pairings A & T and C & G found in Chargaff’s research. We also have a little wider scientific context provided, to where we can start to see how the question of DNA’s structure is crucial for understanding the way genes reproduce and build new cells. This is the question at the heart of how all living organisms are formed and maintain themselves.
