148 IMMUNE SERA 



believe that the immunization with human blood 

 serum gives rise not only to precipitins, but also to 

 amboceptors, which then are able to unite with their 

 corresponding unformed albuminous bodies and so 

 bind complement. Others are of the opinion that 

 the complement is bound by the precipitin-precipitum 

 combination. The test is extremely delicate and 

 has been found trustworthy by a number of inves- 

 tigators. In view of the importance of such tests 

 in medico-legal cases, Neisser and Sachs suggest 

 that it should always be used in addition to the 

 well-known Wassermann-Uhlenhuth precipitin test. 



Antiprecipitins Iso-precipitins. Biologically, 

 the precipitins are found to behave like the sub- 

 stances already studied. It is possible, for example, 

 by injecting an animal with a precipitin, say 

 lactoserum, to obtain an antiprecipitin, an anti- 

 lactoserum, which counteracts or inhibits the 

 action of the precipitin. This is entirely analo- 

 gous to the antihsemolysins, the antispermotoxin, 

 etc. 



If rabbits are treated with rabbit serum, a serum 

 is obtained which will, in certain cases, precipitate 

 the serum of other rabbits. This was done by 

 Schiitze, and he called this serum iso- precipitin. 

 Whether or not iso-precipitins ever occur in normal 

 serum has not yet been definitely established. 

 Their occurrence in human serum might be of 

 importance in homologous transfusion. 



