160 MODERN BIOLOGIC THERAPEUSIS 



serum being tested contains specific antibodies, 

 the complement soon becomes used up or fixed 

 so that it no longer remains free; but with a 

 negative serum containing no antibodies, the 

 complement is left free. This is the first step 

 in the process. 



At the end of the half-hour incubation period, 

 the tubes are removed from the water bath and 

 definite quantities of hemolytic amboceptor and 

 sheep's red cells are added. The tubes are 

 thoroughly shaken to cause a uniform mixture 

 and are returned to the water bath for one hour. 

 At the end of this time, the tubes are removed 

 from the water bath and the reaction recorded. 



If the complement has remained free (show- 

 ing that the serum contained no specific anti- 

 bodies) it acts with the hemolytic amboceptor 

 causing dissolution of the cells, thereby liberat- 

 ing the hemoglobin and producing a clear trans- 

 parent liquid. This result is called hemolysis 

 and constitutes a negative reaction. If the 

 serum contained specific antibodies, the com- 

 plement will have been fixed by means of the 

 antibodies to the antigen. In the formation of 



