474 SCIENCE PROGRESS 



the ovum into the blood, of which they are not normal con- 

 stituents. Presumably means exist whereby these are destroyed. 

 Abderhalden finds that normal blood plasma and serum are 

 without action on the peptones prepared from human placenta 

 but that they are hydrolysed by blood plasma from pregnant 

 women and even from pregnant animals ; and in this case the 

 effect is specific, little or no action taking place either with 

 ordinary albuminous materials or with peptones prepared from 

 them. The effect is noticeable from the first month of 

 pregnancy to the close but disappears within eight days after 

 delivery. 



To ascertain whether action had taken place, Abderhalden 

 originally used either the optical method or subjected the crude 

 mixture of peptone and plasma to diffusion and applied the 

 well-known biuret test to the diffusate. Recently an important 

 new test has been introduced. 



In 1910, Dr. S. Ruhemann was led to prepare a substance to 

 which he gave the name trikctohydrindene hydrate, a compound 

 represented by the formula — 



C,H 4 <£o>C(OH) 2 



This compound behaves in a most characteristic manner 

 with amino-compounds and when warmed with amino-acids 

 gives rise to coloured products : the test is an extraordinarily 

 sensitive one, so that if a solution containing a very minute 

 quantity of the keto-compound and of an amino-acid (glycine, 

 alanine, leucine, tyrosine, etc.) be warmed, a blue colour rapidly 

 makes its appearance. 1 



The proportion of amino-acids present in normal blood is 

 so minute that they cannot be detected in it by means of this 

 test but in pregnancy they are at once apparent. To apply the 

 test, a little of the serum is first subjected to diffusion, as 

 peptones and proteins also give the blue colour ; the diffusate 

 is then warmed with a little of the keto-compound. No other 

 condition has been discovered in which the test gives positive 

 results — so that it is of great diagnostic value. 



It has been the fashion of late — especially among physicists 

 — to decry the work of chemists and to stigmatise them as mere 



1 Chem. Soc. Trans., 19 10, 2025. 



