LYSINS 151 



addition of a small amount of unheated blood serum from a non- 

 immune animal would "reactivate" the heated inactive immune serum 

 and restore its bactericidal power to its original level. These experi- 

 ments collectively demonstrated clearly that: 



1. Normal sera had an inherent but limited destructive action upon 

 a variety of bacteria. 



2. That this destructive or bactericidal action could be greatly 

 increased for specific organisms through repeated injections of sub- 

 lethal doses of them. 1 



3. That both normal and immune sera lost their bactericidal prop- 

 erties by heating them to 55 C. for half an hour. 



4. That immune sera would regain their specific bactericidal power 

 if a small amount of fresh normal blood serum of a non-immune 

 animal were added to them. 2 



Bordet 3 showed similarly that the red blood cells of an alien animal 

 were also destroyed to a limited degree by the serum of a normal 

 animal, but that the destruction could be greatly increased for specific 

 erythrocytes if they were repeatedly injected into an experimental 

 animal. The blood serum becomes specifically hemolytic. Here 

 again Bordet 4 found that heating an immune serum to 55 C. for 

 thirty minutes destroyed its activity, but that a small amount of 

 fresh serum from a non-immune animal (whose serum per se would 

 not dissolve the homologous cells) would reactivate the serum. Thus, 

 both specific bacteriolytic sera and specific hemolytic sera must con- 

 tain two distinct components a thermostabile component resisting 

 an exposure to 55 C. for half an hour and contained only in the 

 immune serum, and a thermolabile component destroyed or inacti- 

 vated at 55 C., which is present both in active immune bacteriolytic 

 and hemolytic sera, and also in normal sera. To the thermolabile 

 substance present in unheated normal and immune sera, Bordet gave 

 the name "alexin;" to the thermostabile specific substance in immune 

 sera he gave the name "substance sensibilitrice." He regarded the 

 "substance sensibilitrice" as a sensitizer or mordant which made 

 bacteria or blood cells vulnerable to the ferment-like or digestive 

 action of the "alexin." 



Ehrlich and Morgenroth 5 studied the phenomena of hemolysis in 



1 Presumably leaving the original non-specific bactericidal power at its initial level 

 for all except the specific organism, and possibly for closely related forms. 



2 Moxter, Cent. f. Bakt., 1899, xxvi, 344. 



3 Loc. cit. 



4 Ann. Inst. Past., 1898, xii, No. 10. 



5 Berl. klin. Wchnschr., 1899, No. 1 and 22. See also Collected Studies on Immunity, 

 Ehrlich, translated by Bolduan, 1910. 



