While the relaxative hormone of sows' corpora lutea produces no other physiological reaction, as far as we know, other than relaxation of the pelvic ligaments, a second hormone is responsible for such reactions as inhibition of ovulation, production of pseudopregnancy in rabbits, vacuolation of the vaginal mucosa of rats and production of a premenstrual endometrium in the uterus of monkeys. The physiologically active material, which is responsible for these reactions, is present in the fractions from which the relaxative hormone has been removed. We have, therefore, 2 separate and distinct hormones elaborated by the corpora lutea of the sow. The following reports the separation of the 2 hormones, and the preparation of a highly purified extract, containing the second hormone of the corpus luteum. For convenience we shall, in this paper, refer to this hormone as hormone “B”. The extract is prepared in exactly the same manner as that described in the previous paper, for the relaxative hormone, up to the point where the active principles are taken up in 97% alcohol, with one important exception: Hormone “B” is somewhat soluble in acetone so ether must be used to remove the last traces of fatty material. The hormone is insoluble or very slightly soluble in ether, consequently the fats may be removed with no significant loss of hormone. The 97% alcoholic extract is evaporated to semidryness leaving a residue, which contains both of the corpus luteum hormones. From this point, either of two methods may be used to separate the hormones. Procedure I. The residue, from the evaporation of the 97% alcoholic extract, is dissolved in glacial acetic acid and the relaxative hormone crystallized and purified as previously described.
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