40 FEMALE BITTERLING I 



the case of urine rich in steroids — e.g. towards the end of 

 pregnancy — it would be in the neighbourhood of i A.U., 

 as measured 1 2 hours after the urine is added to the aquarium 

 water. 



On the basis of these facts DUYVENE DE WiT assumed 

 that there is present in urine an unknown, strongly active 

 element, characterized only by its action in the ovipositor 

 test. He measured the concentration of luteidin of a large 

 number of samples of urine, expressed in A.U. per ml of 

 urine, and arrived at the conclusion that the secretion, in 

 women, is abundant and fairly constant during pregnancy, 

 and at other times variable, with a maximum during the 

 corpus luteum stage, when pregnancy values are reached. 



Now what kind of substance does this word "luteidin" 

 denote? 



To supply the answer to this question, HeintzBERGER 

 made investigations, which, however, — owing to various 

 causes — could not be terminated. 



Luteidin is a substance soluble in water and, in this solu- 

 tion, labile, as is evident, for example, from the fact that 

 active urine, with a latent period of 5 ^ hours, when kept 

 at room temperature for 2 days, still produces the same 

 growth as before, but that the latent period is then reduced 

 to 2 hours. The entire curve is shifted forward without any 

 change in its form, so that a single measurement, e.g. after 

 1 2 hours, does not even betray this fact. This shortening of 

 the latent period may also be obtained by just bringing the 

 urine to the boil. In any attempt at isolating luteidin, there- 

 fore, it is certain that none of the usual methods of urine 

 extraction can be applied which consist in the acidification of 

 the urine with concentrated HCl, followed by prolonged 

 extraction with ether or benzene on the steam-bath. When 

 kept in a refrigerator, however, the urine remains unchanged. 



Testing is done at a temperature of 22° C, i.e., slightly 

 higher than room temperature. This gave VAN KOERSVELD, 

 who performed the tests, the idea that it might be possible 

 to measure the disintegration-rate of luteidin. To this end 

 he added active urine to the aquarium water, but did not put 



