THE HORMONES IN HUMAN REPRODUCTION 



knew well, only in very slight amounts. He guessed that like 

 Iscovesco's, Fellner's, and Herrmann's materials it might be 

 soluble in fat solvents. Fortunately this was correct, and he 

 found at once that the potent substance is soluble in alcohol, 

 a very helpful thing because when strong alcohol is added to 

 a beaker of follicle fluid it throws down the troublesome pro- 

 teins but leaves all the potency in the clear supernatant fluid, 

 which can be decanted and subjected to further analysis. The 

 hormone is also soluble in ether, chloroform, and acetone. In 

 this respect it resembles the fats and therefore goes along 

 with them through the various solutions ; but Doisy was able 

 to get rid of these substances by the familiar expedient of 

 cooking the extract with a little alkali. The fats were thus 

 converted to soaps and could be washed away with water, 

 leaving a small amount of non-saponifiable oil, in which was 

 now concentrated almost all the potency of the original follicle 

 fluid. 



For theoretical reasons not now important, Allen and 

 Doisy believed their active principle was peculiar to the large 

 ovarian follicles, but other workers soon found it in the rest 

 of the ovary. There is a little in the corpus luteum, and very 

 much in the placenta. Robert Frank and his colleagues found 

 it in the blood of female animals. It even turned up in the 

 sex organs of plants, for example in the catkins of willow trees 

 and in palm kernels. 



Incidentally, it was now obvious that this estrogenic hor- 

 mone (as we may call it, because it initiates the estrous 



Plate XV. Effects of the estrogenic hormone on the vagina of the rat. A^ 

 section of vagina 10 days after castration. B, cells from contents of vagina at 

 this time; leucocytes only are seen. C, section of vagina of castrated animal 

 36 hours after an injection of estrogen. Note thickening of vaginal lining. 

 D, cells from vaginal contents of same animal. Epithelial cells now predominate 

 in the vagina. E, section of vagina in estrous condition 48 hours after beginning 

 of treatment with estrogenic hormone. Surface cells cornified, forming clear 

 surface layer. F, vaginal cells of same animal, showing cornified cells only. 

 Greatly magnified. From Sex and Internal Secretions, by courtesy of Edgar 

 Allen and the Williams and Wilkins Company. 



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