ENDOCRINE ARITHMETIC 



ments on rabbits and sows, and the final emergence into pure 

 theory in terms of molecules by the billion. Toward the end of 

 my discourse, however, the hearers settled down and discussed 

 the calculation quite seriously. Our chairman, in fact, sat up 

 all the next night figuring on a furtiier stage of the investiga- 

 tion, and in the morning, weary but still enthusiastic, brought 

 me several more pages of arithmetic. What follows here is the 

 substance of that presentation, revised in consideration of 

 some facts contributed in discussion by members of the sym- 

 posium, and corrected also in the light of subsequent knowl- 

 edge. 



1. How much progesterone is produced daily by a given 

 amount of corpus luteum tissue? We begin by considering the 

 fundamental property of the corpus luteum, namely, to pro- 

 duce progestational proliferation of the lining of the uterus 

 (Chapter V, page 107 and Plate XVII, B), This has been 

 studied chiefly in the rabbit, in which species it shows up with 

 especial clearness. In a rabbit there are, of course, several 

 corpora lutea at a time. By cutting down their number by sur- 

 gical operation on the ovaries under anesthesia, it is possible 

 to ascertain the minimum number of corpora lutea necessary 

 to produce full progestational proliferation as in figure D 

 of Plate XVIII. 



(a) A young Frenchman, Joublot, the first to try such an 

 experiment (1927), found that two corpora lutea were suffi- 

 cient, but one was insufficient. I tried it also, and found that 

 one corpus was sufficient, but half a corpus insufficient. Lucien 

 Brouha, then in Belgium (1934), found one or two corpora 

 lutea necessary. In our calculations we shall take the average 

 of these three results and start with the assumption that in 

 the rabbit one corpus luteum produces just sufficient pro- 

 gesterone to cause typical eff'ects upon the lining of the uterus. 



(b) To produce the same effect with progesterone, giving 

 one injection per day, requires about 0.2 milligrams daily. 

 Dr. Pincus reports that by giving the hormone in two injec- 



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