ENDOCRINE ARITHMETIC 



beginning on the day of operation. A slight but definite 

 decrease in the color of the sex skin took place during the 

 next 10 days. The swelling of this region diminished also, 

 although not to the same extent as the color, and on the 10th 

 day, in spite of the administration of estrone, external vaginal 

 bleeding began. 



From the facts that the condition of the sex skin retro- 

 gressed very slowly and external bleeding did not begin until 

 the 10th day, that is to say later than if the animal had been 

 given no estrogen at all, it seems that the dose of 125 inter- 

 national units daily was almost but not quite sufficient to 

 maintain the animal in the same condition as before removal 

 of the ovaries. We may estimate therefore that 150 or 200 

 international units would have been required to substitute 

 completely for the ovaries. 



Another method of arriving at the desired information 

 depends upon the fact that effective action of progesterone 

 upon the endometrium to produce the progestational ("pre- 

 menstrual") condition in castrated female monkeys requires 

 that an estrogenic hormone be administered in conjunction 

 with the hormone of the corpus luteum. Engle of Columbia 

 University (1937) stated that a satisfactory combination 

 for the castrated Rhesus monkey is 30 AUen-Doisy rat units of 

 estrone (this is approximately 150 international units) daily 

 with 0.5 Corner- Allen unit of progesterone (approximately 

 0.5 milligram). Hisaw and Greep (1938) gave a similar figure, 

 i.e. about 150 international units of estrogen with 0.5 mg. of 

 progesterone. These experiments are subject to the difficulty 

 that they involve varying the dosage of two hormones simul- 

 taneously. The animals used by Hisaw and Greep were, more- 

 over, relatively young, and the progestational changes in- 

 volved were not as elaborate as the natural progestational 

 state. The result fits however those obtained above in giving 

 150 international units of estrone as somewhat less than an 



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