166 INFECTION AND RESISTANCE 



Bordet and Gay 59 accordingly studied the Ehrlich-Sachs phe- 

 nomenon carefully and obtained results which confirmed the experi- 

 mental data of these writers but cast much doubt upon the validity 

 of their conclusions. 



In going over the experiments of Ehrlich and Sachs, Bordet and 

 Gay made an observation which had apparently escaped the atten- 

 tion of the former investigators. Heated bovine serum has but a 

 slight agglutinating power for guinea pig corpuscles. Fresh horse 

 serum agglutinates them only slightly and slowly. On the other 

 hand a mixture of the two sera agglutinates them very rapidly and 

 completely. The bovine serum apparently possessed an accelerating 

 or fortifying influence both upon the weakly active normal hemoly- 

 sins and agglutinins in the horse serum. Bordet and Gay conse- 

 quently suspected that this property might be due to an undescribed 

 substance, peculiar to the bovine serum. To eliminate the uncertain 

 elements obtaining in experiments in which normal sensitizer is 

 used they now experimented with guinea pig corpuscles, anti-guinea 

 pig sensitizer (from a rabbit immunized with guinea pig blood cells) 

 and guinea pig alexin. 



They found that sensitized guinea pig cells are hemolyzed by 

 guinea pig alexin very slowly and imperfectly, as is often the case 

 when the alexin comes from the same animal species as the cells. 

 When heated bovine serum was added to the complex of sensitized 

 cells and alexin, rapid agglutination and hemolysis resulted. Their 

 experiments may be tabulated as follows : 



1. Cells + guinea pig alexin + heated bovine serum = no agglutination; 



very slight hemolysis on next day. 



2. Cells + sensitizer -+- heated bovine serum = slight agglutination; no 



hemolysis. 



3. Cells + sensitizer + alexin + bovine serum = powerful agglutination 



and complete hemolysis in 10 minutes. 



4. Cells + sensitizer + alexin = very slight agglutination and incomplete 



hemolysis in 30 minutes. 



5. Cells + sensitizer = slight agglutination; no hemolysis. 



In tube (1) the slight hemolysis was due to the small amount of 

 normal sensitizer present in the bovine serum, and the slight agglu- 

 tination in tube (5) is referable to the agglutinating power of the 

 sensitizer. In tube (3) we see the powerfully accelerating effects 

 exerted both upon agglutination and hemolysis when bovine serum 

 acts upon sensitized corpuscles in the presence of alexin. 



Bordet and Gay's interpretation of the Ehrlich-Sachs phenom- 

 enon, in the light of these new experiments then, is, in their own 

 words, as follows: "When guinea pig corpuscles are added to a 

 mixture of the two sera they are affected by the sensitizer of the 

 horse serum and, to a certain extent, by the sensitizer in the heated 



59 Bordet and Gay. Ann. de I'Inst. Past., Vol. 20, 1906, p. 467. 



