42 FEMALE BITTERLING I 



highest value ever reached by the end of pregnancy is only 

 about 15 — 29 mg/1. For that matter, it already follows from 

 what has been said with respect to the secretion in both men 

 and women that we could hardly have to do here with this 

 substance. 



What did, however, become clear from this investigation 

 was that the active portion of the luteidin molecule finally 

 arrives, during the purification of the urine-extracts, in about 

 equal quantities, in the neutral fraction which also contains 

 the androgenic substances, and in the weakly-acid (phenol) 

 fraction, in which the estrogenic steroids are also contained. 



Indeed, everything points to the presence in urine of a not 

 yet identified substance with a high activity in the ovipositor 

 test, although it may, of course, be possible that the substance 

 in question is known as such, but that its biological activity 

 has not yet been revealed. 



The facts described above having been realized, we pro- 

 ceeded to extract 100 1 urine of pregnant women, with a 

 view to using this extract as initial material in an attempt 

 to isolate luteidin. It is true, that, in this urine, there are large 

 quantities of estrogenic steroids, pregnanediol and kindred 

 substances; an advantage, however, is that luteidin secretion 

 is both high and constant, so that there is no risk of obtaining 

 large quantities of urine extract which subsequently turn out 

 to be nearly or wholly inactive. 



The first experiments were made with a crude extract of 

 25 1 urine, whilst at the same time the remaining 75 1 were 

 extracted. As is usual in such experiments the comparative 

 solubility in the various solvents was first examined. There 

 is not, however, very much choice, as it appears that shaking 

 up the butanol-extract with ether, benzene and suchlike 

 eliminates practically no impurities (although any free estriol, 

 etc. is removed); the "dry-rest", therefore, hardly diminishes 

 at all. After a few trials, however, it was found that a puri- 

 fication of roundabout five times is to be obtained by shaking 

 out the butanolic solution of the extract with o. i N KOH. 

 The luteidin then remains in the butanol-phase. Into 

 the alkaline fraction go, e.g., the estrogens, which should be 



