88 Natur e of Abderhalden ReacHon [March, 



gestion of placenta depends in the Abderhalden test are essentially 

 different from the substances obtained by immunisation of rabbits, 

 or that they are both ahke, but not enzymic in character. Further 

 experiments along this hne convinced us that the latter alternative is 

 the correct one. We corroborated the earlier findings of Stephan 

 and Hauptmann, that the complement plays an important part in 

 the Abderhalden test, but also found that the specific enzymes (so- 

 called) of Abderhalden behave, in every way, like antibody, as under- 

 stood in the terminology of immunity. We also succeeded in ex- 

 hausting the serum of pregnant individuals of its specific elements, 

 and in actually sensitizing placenta-protein so as to obtain a positive 

 ninhydrin test after the addition of fresh human or animal (male 

 or female) serum. 



Having thus convinced ourselves that the Abderhalden test did 

 not depend on any enzyme specifically able to digest placenta-pro- 

 tein (since the addition of any serum favored a positive ninhydrin 

 test, provided the serum was added to previously sensitized placenta) 

 we concluded that the ninhydrin test is nothing but a new expression 

 of the phenomenon which previously had been brought to light by 

 the indicator of Bordet-Gengou, viz., hemolysis. Viewed in this 

 light the Abderhalden test, without offering anything new on the 

 theory or mechanism of immunity, introduces a very effective indi- 

 cator of the occurrence of the reaction. 



As to the mechanism of the test proper, I wish to State without 

 going into the details of our experiments, that I have proof of the 

 fact that in the Abderhalden test placenta is not digested, but that 

 the amino-acids and Polypeptids, which dialyse through the wall of 

 the thimble, come from the serum. I have noted their appearance 

 in a serum after it had been incubated with placenta-protein for some 

 time, and under certain conditions. These dialysable products result 

 from the digestion of the globulin in the serum by the accompanying 

 serum protease; in other words, as a result of the autodigestion of 

 the patient's serum. 



The proteolytic ferment responsible for this auto-digestion is not 

 specific, but is present in all fresh sera, in vivo as well as in vitro. 

 The action of this ferment, while in the body, is arrested by the 

 antitryptic action of serum constituents, among which are non-sat- 

 urated fatty acids. The combination of any specific antibody (not 



