THE TECHNIQUE OF SERUM REACTIONS 



261 



In all hemolytic tests the time element is important. No hemolysis 

 should be adjudged as incomplete unless at least one hour has elapsed. 



Isohemolysins and Iso-agglutinins. It is often necessary to carry 

 out hemolytic and hemagglutinating tests on the blood corpuscles of one 

 human being with the serum of another in order to determine the ad- 

 visability of performing transfusion. In this case, the serum of the re- 

 cipient is mixed with a corpuscle emulsion of the cells of the donor, 

 and vice versa. This is conveniently done in small pipettes by the 

 method of Ottenberg. 



By the determination of iso-agglutinins and isohemolysins all human beings 

 can be divided into four groups according to Landsteiner and others. 



TABLE FOR ISO-AGGLUTININS SERA 



II 



III 



IV 



These groupings are permanent and inheritable, following Mendel's laws. 



