THE TECHNIQUE OF SERUM REACTIONS 313 



tity of complement to be used in these tests can be given. In each 

 case the particular complement used should be titrated to determine 

 the minimum quantity which will produce hemolysis of 1 c.c. of the 

 sensitized cell suspension. 



In the actual test, mixtures are made of the corpuscle emulsion, 

 the inactivated immune serum, and complement in small test tubes 

 and the volumes of the various tubes made equal by the addition 

 of definite quantities of salt solution. The contents of the tubes 

 are thoroughly mixed and the tubes put in the incubator or in a 

 water bath at 37.5 C. If complete hemolysis occurs, the fluid in 

 the tube will assume a deep Burgundy red. If no hemolysis occurs, 

 the fluid will remain uncolored and the corpuscles will settle out. 

 Incomplete hemolysis will be evidenced by a lighter tinge of red 

 in the tube and the settling out of a varying quantity of blood 

 corpuscles. 



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

 should be adjudged as incomplete unless at least one hour has 

 elapsed. 



ISOAGGLUTININS 



In 1901 Landsteiner found that 22 individuals whose blood he 

 studied could be divided into three groups with respect to iso- 

 hemoagglutinins. It was found, in other words, that, analogous to 

 the isolysins described by Ehrlich and his co-workers in the case 

 of goats, human beings could exert specific hemoagglutinating action, 

 and, in some cases, hemolytic action upon the corpuscles of other 

 individuals. This is, of course, of the greatest importance in con- 

 nection with transfusion tests. It is hardly worth while to go into 

 detailed historic considerations in this place. Subsequent investiga- 

 tion has shown that there are four main isoagglutinating groups 

 among human beings. The first classification of this kind was made 

 by Jansky. Subsequently, a similar classification was made by Moss, 

 but unfortunately Moss reversed the tabulation in such a way that 

 Jansky 's group I became Moss's group IV, and vice versa. In 

 America the Moss classification has become universal, and, for this 

 reason, the table given below represents the Moss classification. It 

 must be borne in mind by all workers who control human transfu- 

 sions on this test, however, that such a reversal of Moss and Jansky 

 exists, and whenever report is rendered it must be made entirely 



