1914] J- Bronfenhrenner, W. T. Mitchell, M. J. Schlesinger 387 



The first evidence pointing in this direction was offered by Ab- 

 derhalden and his pupils, when they found that only fresh sera of 

 pregnant women were capable of cleaving the placenta-protein in the 

 Abderhalden reaction. The natural suspicion regarding the role 

 of the complement in the test, led Stephan^ to discover the fact 

 (later confirmed by Hauptmann^ and others) that the addition of 

 fresh rabbit, guinea-pig, or any other, serum might reactivate inac- 

 tive serum, and thus render the test possible with old sera. 



In our^ own experiments we tried to make use of the known 

 property of antibody of sensitizing the antigen at a low temperature, 

 which excludes the activity of the complement. We found that 

 there was not only no dialysis in the tube containing placenta and 

 the pregnant serum when the temperature was low, but also that the 

 placenta as well as the serum underwent changes absolutely similar 

 to those we should have expected if we had used, instead, a hemo- 

 lytic amboceptor and corresponding erythrocytes — namely, the serum 

 was deprived of its property of digesting fresh placenta-protein, 

 and the placenta-protein acquired the property of being digested by 

 any fresh serum. Moreover, such a placenta (sensitized?) could 

 also be digested by serum which was deprived of its specific anti- 

 body by exhaustion with placenta in the ice-box. 



The accompanying summary gives the essentials of our results. 



These findings are not only of theoretical importance, inas- 

 much as they furnish further proof of the similarity of the phenom- 

 enon of the Abderhalden to the immunity reaction, but are also of 

 practical value. To those making routine examinations by the 

 Abderhalden method, it is known that the blood of a patient taken 

 under certain conditions, as when there is high temperature, pus 

 formation, or recent Ingestion of a meal, may contain an amount of 

 amino acid sufficient to mask the specific reaction. Whereas the last 

 mentioned factor can be regulated with little inconvenience to the 

 patient, blood being taken before breakfast, it is impossible to obviate 

 the complications in the other cases. In such instances, where the 

 serum alone contains dialysable reactive substances, the difference in 

 the strength of the reaction with ninhydrin of the control tube, and 

 the tube containing placenta (or other substratum), as well as serum, 



^Stephan: Münch. med. Woch., 1914, no. 15, p. 801. 

 2 Hauptmann: Münch. med. Woch., 1914, no. 21, p. 1167. 



