DOUBLE HELIX

Chapter 1: The Cavendish Laboratory

I have never seen Francis Crick in a modest mood. This has nothing to do with his present fame. Already he is much talked about, usually with great respect, and one day he may be considered an equal to Rutherford or Bohr. But this was not true when, in the autumn of 1951, I came to the Cavendish Laboratory of Cambridge University to join a small group of physicists and chemists working on the structure of proteins. At that time Francis was thirty-five, but almost totally unknown. Although some of his colleagues respected his quick mind and frequently asked his advice, he was often not appreciated, and most people thought he talked too much.
Leading the unit to which Francis belonged was Max Perutz, an Austrian-born chemist who came to England in 1936. He had been collecting X-ray diffraction data from protein crystals for over ten years and was just beginning to get results. Helping him was Sir Lawrence Bragg, the director of the Cavendish. For forty years Bragg, a Nobel Prize winner and one of the first crystallographers, had been watching X-ray diffraction methods solve structures of increasing difficulty. In the immediate postwar years he was especially keen on the possibility of solving the structure of proteins, the most complex of all molecules.
Somewhere between Bragg the theorist and Perutz, the experimenter was Francis, who occasionally did experiments but was more often interested in theories for solving protein structures. Often he had a new idea, became enormously excited, and would immediately tell anyone who was willing to listen. A day or two later he would often realize that his theory did not work and return to experiments, until he got bored with them and turned again to theory.
These ideas brought an atmosphere of excitement to the laboratory, where experiments usually lasted several months to years. This came partly from the volume of Cricks voice; he talked louder and faster than anyone else, and when he laughed everyone knew where he was in the Cavendish. Most people enjoyed these exciting moments, especially when we had time to listen closely and to tell him when we lost the logic of his argument. But there was one significant exception. Conversations with Crick frequently upset Sir Lawrence Bragg, and the sound of his voice was often enough to make Bragg move to a safer room. Only infrequently would he come to tea in the Cavendish, since it meant he had to hear Crick's loud voice in the tearoom. Even if he stayed away, Bragg was not completely safe. On two occasions, the corridor outside his office was flooded with water pouring out of a laboratory in which Crick was working. Francis, with his interest in theory, had not properly connected the rubber tubes to his pump.
At the time of my arrival, Francis's theories spread far beyond the boundaries of protein crystallography. Anything important would attract him, and he frequently visited other laboratories to see which new experiments had been done. Though he was generally polite to colleagues who did not realize the real meaning of their latest experiments, he did not attempt to hide this fact from them. Almost immediately, he would suggest a number of new experiments that would confirm his analysis. Moreover, he could not stop himself from later telling anybody who would listen how his clever new idea might move science forward.
As a result, an unspoken but real fear of Crick existed, especially among his more junior colleagues. The quick manner in which he seized their facts and tried to make sense of them frequently made his friends worry that he would actually succeed. This would show the world the loose thinking that was hidden behind the good manners and polite conversation of the Cambridge colleges.
Though he had the right to dine one night a week at Caius College, Francis did not belong to the staff of any college. Partly this was his own choice. Clearly, he did not want the unnecessary responsibility of teaching students. Another problem was his laugh, against which many academics would certainly rebel if they had to hear it more than once a week. I am sure this occasionally bothered Francis, although he knew that most college dinners were dominated by boring, middle-aged men incapable of either amusing or educating him. His friends, who knew he was an entertaining dinner companion, made much effort on his

behalf, but they were never able to hide the fact that Francis might get into an argument with anyone present at the table.
Before my arrival in Cambridge, Francis only occasionally thought about deoxyribonucleic acid (DNA) and its role in genetics. This was not because he thought it was uninteresting. Quite the opposite. A major reason why he had left physics and developed an interest in biology had been the reading in 1946 of What is Life? By the respected theoretical physicist Erwin Schrodinger. This book stated the belief that genes were the most important parts of living cells and that, to understand what life is, we must know how genes act. When Schrodinger wrote his book (1944) there was a general acceptance that genes were special types of protein molecules. But almost at the same time the bacteriologist O.T. Avery was carrying out experiments in New York which showed that physical characteristics could be passed from one bacterial cell to another by purified DNA molecules.
Since DNA was known to occur in the chromosomes of all cells, Avery's experiments strongly suggested that future experiments would show that all genes were made up of DNA. If true, this meant to Francis that DNA, not proteins, would provide the key to enable us to find out how the genes determined, among other characteristics, the colour of our hair and eyes, probably our intelligence and maybe even our ability to amuse others.
Of course, there were scientists who thought that the evidence favoring DNA was unclear and preferred to believe that genes were protein molecules. Francis did not worry about them. One could not be a successful scientist without realizing that, in contrast to the popular belief supported by newspapers and the mothers of scientists, a large number of scientists are not only narrow-minded and dull, but also just stupid.
Francis, however, was not then prepared to jump into the DNA world. Its basic importance did not seem a strong enough reason to lead him out of the protein field, which he had worked in for only two years and was just beginning to understand thoroughly. In addition, his colleagues at the Cavendish were only slightly interested in the nucleic acids, and even in the best of financial circumstances, it would take two or three years to set up a new study group, which would use X-rays to look at the DNA structure.
Moreover, such a decision would create an awkward personal situation. At this time, molecular work on DNA in England was considered to be the personal property of Maurice Wilkins, who worked at Kings College, London. Like Francis, Maurice had been a physicist and also used X-ray diffraction as his principal method of study. It would have looked very bad if Francis had jumped in on a problem that Maurice had worked on for several years. The matter was even worse because the two, almost equal in age, knew each other quite well. Maurice was unmarried, and before Francis remarried, they had frequently met for lunch or dinner to talk about science.
It would have been much easier if they had been living in different countries. In England, all the important people, if not related by marriage, seemed to know each other, and it would have been seen as unfair for Francis to move in on Maurice's problem. In France, where this sense of unfairness did not exist, these problems would not have occurred. The States would also not have permitted such a situation to develop. One would not expect someone at Berkeley to ignore a challenging problem just because someone at Cal Tech had started first. In England, however, it simply would not look right.
Even worse, Maurice continually annoyed Francis by never seeming enthusiastic enough about DNA. Moreover, it was increasingly difficult to take Maurice's mind off his assistant, Rosalind Franklin. He was not in love with Rosy, as we called her from a distance. Just the opposite - almost from the moment she arrived in Maurice's laboratory, they began to upset each other. Maurice, a beginner in X-ray diffraction work, wanted some professional help and hoped that Rosy, a trained crystallographer, could speed up his work. Rosy, however, did not see the situation this way. She claimed that she had been given DNA as her own problem and she refused to think of herself as Maurice's assistant.
I suspect that in the beginning Maurice hoped that Rosy would calm down. But she was a determined woman. By choice, she did not emphasize her female qualities. Though her features were strong, she might have been quite attractive if she had taken even a mild interest in clothes. She did not. There was never any lipstick to contrast with her straight black hair, while her dresses showed no imagination at all. So it would have been easy to believe that she was the product of a dissatisfied mother who emphasized the importance of

a professional career as an alternative to marriage to a dull man. But this was not the case. In fact, she was the daughter of a comfortable and cultured banking family.
Clearly, Rosy had to go or be controlled. The former was obviously preferable because her aggressive moods made it very difficult for Maurice to think in peace about DNA. There were times when he could see some reason for her complaints. For example, King's had two social rooms, one for men, the other for women, certainly an arrangement from the past. But he was not responsible, and it was no pleasure to be blamed for the fact that the women's social room was small and dirty while money had been spent to make him and his friends more comfortable when they had their morning coffee.
Unfortunately, Maurice could not see any decent way to sack Rosy. First, she had been given the impression that she had a job for several years. Also, she had a good brain. If she could keep her emotions under control, there would be a good chance she could really help him. But hoping and waiting for relations to improve was taking a chance, since Cal Tech's great chemist Linus Pauling was not limited by the rules of British fair play. Sooner or later Linus, who was just fifty, was bound to try for the most important of all scientific prizes. We knew that Pauling could not be the greatest of all chemists without realizing that DNA was the most golden of all molecules. Moreover, there was definite proof. Maurice had received a letter from Linus asking for a copy of the crystalline DNA X-ray photographs. After some hesitation he wrote back saying he wanted to look more closely at the data before releasing the pictures.

Part 2

Carla is going to leave the shop. But where is her umbrella?
There is one umbrella near the door. It is not a red umbrella. It is not Carla’s umbrella.
This umbrella is old and black. It has a pattern of yellow ducks. It is not smart. Carla takes the umbrella. “This is not my lucky day!” Carla says.
Carla walks to the town square. A young man speaks to her.
Hello!
He smiles.
Carla does not know this young man. She walks away quickly.
The young man is following Carla. She walks into a crowd of people. The young man follows the black and yellow umbrella. “Hello! Wait!”  A young man says.

Part 3

Carla turns. She looks at the young man. She is angry. “Go away!” she says.
The young man is sad. “Marisa, I’m sorry!” he says.  “I’m very late.”
“I’m not Marisa,” Carla shouts. “You are not Marisa?” says the young man. He points at the black umbrella with yellow ducks. “That’s her umbrella.” “Oh,” says Carla. “Who is Marisa?” “I don’t know Marisa,” says the young man. “I’m going to meet her. We are going to have coffee. It is my cousin’s idea. Marisa works with my cousin.” “I am not Marisa!” says Carla again.
 “My cousin has a photo of Marisa,” says the young man. “She’s tall. You’re tall. Her hair is short and dark. Your hair is short and dark. In the photo, she has an umbrella.
It’s a black umbrella with yellow ducks. You have a black umbrella with yellow ducks!”
Carla looks up at the old umbrella. “Marisa is a thief,” she thinks. “She has my new red umbrella.” Carla is angry again. “Please don’t be angry,” says the young man. He looks at his watch “It’s three o’clock. Marisa goes to work at 2.30. I can’t meet her now. It’s too late.” He smiles at Carla. “Let’s have coffee together,” he says.
Carla thinks for a moment. “OK,” she says. “Let’s go to my aunt’s café.” The young man smiles again. “That will be great,” he says. “My name is Paul. I’m a law student - third year," a young man says. “I’m Carla. I’m a student too. I’m studying science,” Carla says.

Part 4

Carla sits in the café with Paul. They drink coffee. They talk. They laugh and talk.
Suddenly Carla jumps up. “Oh, no!” she says. “It’s late. I must go home. I must study. I’m going to have an exam tomorrow.” “Good luck! Will you meet me again?” Paul says. “Yes. That will be nice.” Carla says.
It is almost dark. The town square is quiet.
Carla sees a tall young woman. The young woman has short dark hair. She has a smart umbrella. It is a red umbrella.
The young woman is Marisa!
Marisa sees the old black umbrella with yellow ducks. She is worried. Suddenly, her face is red. “Don’t worry, says Carla. “Keep my red umbrella. I like this umbrella. It’s a lucky umbrella. This is my lucky day!” The rain falls on the umbrellas. Carla smiles. Then she runs home.