A HORMONE FOR GESTATION 



who had occasion to administer progesterone to human pa- 

 tients whose ovaries had been removed. There will be much 

 more to sa}'^ about this when we come to discuss the menstrual 

 cycle in Chapter VI. 



Meanwhile Willard Allen was makmg successful efforts to 

 purify the hormone. Our crude extracts were already free of 

 protein and we had got rid of the phosphorus-containing fats, 

 always a bother in alcoholic extracts. The next stages were 

 much harder than it was to purify estrone, because unfor- 

 tunately the corpus luteum hormone is destroyed by alkalies. 

 The chemists, therefore, could not get rid of fatty contami- 

 nants by merely turning them into soap and washing them 

 away. By one trick and another, however, Allen successively 

 got rid of the major contaminants, namely fats, fatty acids, 

 and the inert sterol known as cholesterol. He began to get the 

 hormone in crystalline form. Fels and Slotta, then (1931) in 

 Breslau, Fevold and Hisaw (1932) and Allen (1932) ulti- 

 mately obtained an almost perfectly pure crystalline sub- 

 stance of high potency. For his part of this work Willard 

 Allen received the 1935 Eli Lilly Award of the American 

 Chemical Society for the best work in biochemistry done by 

 an American under thirty-one years of age. We now called 

 into consultation Dr. Oskar Wintersteiner of Columbia Uni- 

 versity, a skilled microanalyst. Allen gave him 75 milligrams 

 of the crystals, not much more than the weight of a postage 

 stamp. He completed the purification and found that the 

 hormone is a sterol having 21 atoms of carbon, 30 of hydro- 

 gen and 2 of oxygen. Practically at the same time Slotta, 

 Ruschig and Fels at Breslau, and Butenandt and Westphal, 

 then at Danzig, also reported ultimate purification of the 

 hormone and announced, as probably correct, the formula 

 printed below. Butenandt told me later that the total amount 

 of the hormone he had available with which to work out its 

 structure was 20 milligrams, one-third of the weight of a 



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